Update docs

Co-authored-by: Richard Schreiber <schreiber@rami.io>

doc/development/api/plugins.rst

@@ -121,6 +121,7 @@ This will automatically make pretix discover this plugin as soon as it is instal
 through ``pip``. During development, you can just run ``python setup.py develop`` inside
 your plugin source directory to make it discoverable.
 
+.. _`signals`:
 Signals
 -------
 
@@ -153,6 +154,25 @@ in the ``installed`` method:
 Note that ``installed`` will *not* be called if the plugin is indirectly activated for an event
 because the event is created with settings copied from another event.
 
+.. _`registries`:
+Registries
+----------
+
+Many signals in pretix are used so that plugins can "register" a class, e.g. a payment provider or a
+ticket renderer.
+
+However, for some of them (types of :ref:`Log Entries <logging>`) we use a different method to keep track of them:
+In a ``Registry``, classes are collected at application startup, along with a unique key (in case
+of LogEntryType, the ``action_type``) as well as which plugin registered them.
+
+To register a class, you can use one of several decorators provided by the Registry object:
+
+.. autoclass:: pretix.base.logentrytypes.LogEntryTypeRegistry
+   :members: register, new, new_from_dict
+
+All files in which classes are registered need to be imported in the ``AppConfig.ready`` as explained
+in `Signals <signals>`_ above.
+
 Views
 -----
 

doc/development/implementation/logging.rst

@@ -20,7 +20,8 @@ To actually log an action, you can just call the ``log_action`` method on your o
 
 .. code-block:: python
 
-   order.log_action('pretix.event.order.canceled', user=user, data={})
+   order.log_action('pretix.event.order.comment', user=user,
+                    data={"new_comment": "Hello, world."})
 
 The positional ``action`` argument should represent the type of action and should be globally unique, we
 recommend to prefix it with your package name, e.g. ``paypal.payment.rejected``. The ``user`` argument is
@@ -72,24 +73,101 @@ following ready-to-include template::
    {% include "pretixcontrol/includes/logs.html" with obj=order %}
 
 We now need a way to translate the action codes like ``pretix.event.changed`` into human-readable
-strings. The :py:attr:`pretix.base.signals.logentry_display` signals allows you to do so. A simple
+strings. The :py:attr:`pretix.base.logentrytypes.log_entry_types` :ref:`registry <registries>` allows you to do so. A simple
 implementation could look like:
 
 .. code-block:: python
 
     from django.utils.translation import gettext as _
-    from pretix.base.signals import logentry_display
+    from pretix.base.logentrytypes import log_entry_types
+
+
+    @log_entry_types.new_from_dict({
+        'pretix.event.order.comment': _('The order\'s internal comment has been updated to: {new_comment}'),
+        'pretix.event.order.paid': _('The order has been marked as paid.'),
+        # ...
+    })
+    class CoreOrderLogEntryType(OrderLogEntryType):
+        pass
+
+Please note that you always need to define your own inherited ``LogEntryType`` class in your plugin. If you would just
+register an instance of a ``LogEntryType`` class defined in pretix core, it cannot be automatically detected as belonging
+to your plugin, leading to confusing user interface situations.
+
+
+Customizing log entry display
+"""""""""""""""""""""""""""""
+
+The base ``LogEntryType`` classes allow for varying degree of customization in their descendants.
+
+If you want to add another log message for an existing core object (e.g. an :class:`Order <pretix.base.models.Order>`,
+:class:`Item <pretix.base.models.Item>`, or :class:`Voucher <pretix.base.models.Voucher>`), you can inherit
+from its predefined :class:`LogEntryType <pretix.base.logentrytypes.LogEntryType>`, e.g.
+:class:`OrderLogEntryType <pretix.base.logentrytypes.OrderLogEntryType>`, and just specify a new plaintext string.
+You can use format strings to insert information from the LogEntry's `data` object as shown in the section above.
+
+If you define a new model object in your plugin, you should make sure proper object links in the user interface are
+displayed for it. If your model object belongs logically to a pretix :class:`Event <pretix.base.models.Event>`, you can inherit from :class:`EventLogEntryType <pretix.base.logentrytypes.EventLogEntryType>`,
+and set the ``object_link_*`` fields accordingly. ``object_link_viewname`` refers to a django url name, which needs to
+accept the arguments `organizer` and `event`, containing the respective slugs, and additional arguments provided by
+``object_link_args``. The default implementation of ``object_link_args`` will return an argument named by
+````object_link_argname``, with a value of ``content_object.pk`` (the primary key of the model object).
+If you want to customize the name displayed for the object (instead of the result of calling ``str()`` on it),
+overwrite ``object_link_display_name``.
+
+
+.. code-block:: python
+
+    class ItemLogEntryType(EventLogEntryType):
+        object_link_wrapper = _('Product {val}')
+
+        # link will be generated as reverse('control:event.item', {'organizer': ..., 'event': ..., 'item': item.pk})
+        object_link_viewname = 'control:event.item'
+        object_link_argname = 'item'
+
+
+.. code-block:: python
+
+    class OrderLogEntryType(EventLogEntryType):
+        object_link_wrapper = _('Order {val}')
+
+        # link will be generated as reverse('control:event.order', {'organizer': ..., 'event': ..., 'code': order.code})
+        object_link_viewname = 'control:event.order'
+
+        def object_link_args(self, order):
+            return {'code': order.code}
+
+        def object_link_display_name(self, order):
+            return order.code
+
+To show more sophisticated message strings, e.g. varying the message depending on information from the :class:`LogEntry <pretix.base.models.log.LogEntry>`'s
+`data` object, override the `display` method:
+
+.. code-block:: python
+
+    @log_entry_types.new()
+    class PaypalEventLogEntryType(EventLogEntryType):
+        action_type = 'pretix.plugins.paypal.event'
+
+        def display(self, logentry):
+            event_type = logentry.parsed_data.get('event_type')
+            text = {
+                'PAYMENT.SALE.COMPLETED': _('Payment completed.'),
+                'PAYMENT.SALE.DENIED': _('Payment denied.'),
+                # ...
+            }.get(event_type, f"({event_type})")
+            return _('PayPal reported an event: {}').format(text)
+
+.. automethod:: pretix.base.logentrytypes.LogEntryType.display
+
+If your new model object does not belong to an :class:`Event <pretix.base.models.Event>`, you need to inherit directly from ``LogEntryType`` instead
+of ``EventLogEntryType``, providing your own implementation of ``get_object_link_info`` if object links should be
+displayed.
+
+.. autoclass:: pretix.base.logentrytypes.LogEntryType
+   :members: get_object_link_info
+
 
-    @receiver(signal=logentry_display)
-    def pretixcontrol_logentry_display(sender, logentry, **kwargs):
-        plains = {
-            'pretix.event.order.paid': _('The order has been marked as paid.'),
-            'pretix.event.order.refunded': _('The order has been refunded.'),
-            'pretix.event.order.canceled': _('The order has been canceled.'),
-            ...
-        }
-        if logentry.action_type in plains:
-            return plains[logentry.action_type]
 
 Sending notifications
 ---------------------

src/pretix/_base_settings.py

@@ -75,6 +75,14 @@ FORMAT_MODULE_PATH = [
     'pretix.helpers.formats',
 ]
 
+CORE_MODULES = {
+    "pretix.base",
+    "pretix.presale",
+    "pretix.control",
+    "pretix.plugins.checkinlists",
+    "pretix.plugins.reports",
+}
+
 ALL_LANGUAGES = [
     ('en', _('English')),
     ('de', _('German')),

src/pretix/base/logentrytypes.py

@@ -0,0 +1,253 @@
+#
+# This file is part of pretix (Community Edition).
+#
+# Copyright (C) 2014-2020 Raphael Michel and contributors
+# Copyright (C) 2020-2021 rami.io GmbH and contributors
+#
+# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
+# Public License as published by the Free Software Foundation in version 3 of the License.
+#
+# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
+# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
+# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
+# this file, see <https://pretix.eu/about/en/license>.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
+# <https://www.gnu.org/licenses/>.
+#
+from collections import defaultdict
+
+from django.urls import reverse
+from django.utils.html import escape
+from django.utils.translation import gettext_lazy as _, pgettext_lazy
+
+from pretix.base.signals import EventPluginRegistry
+
+
+def make_link(a_map, wrapper, is_active=True, event=None, plugin_name=None):
+    if a_map:
+        if is_active:
+            a_map['val'] = '<a href="{href}">{val}</a>'.format_map(a_map)
+        elif event and plugin_name:
+            a_map['val'] = (
+                '<i>{val}</i> <a href="{plugin_href}">'
+                '<span data-toggle="tooltip" title="{errmes}" class="fa fa-warning fa-fw"></span></a>'
+            ).format_map({
+                **a_map,
+                "errmes": _("The relevant plugin is currently not active. To activate it, click here to go to the plugin settings."),
+                "plugin_href": reverse('control:event.settings.plugins', kwargs={
+                    'organizer': event.organizer.slug,
+                    'event': event.slug,
+                }) + '#plugin_' + plugin_name,
+            })
+        else:
+            a_map['val'] = '<i>{val}</i> <span data-toggle="tooltip" title="{errmes}" class="fa fa-warning fa-fw"></span>'.format_map({
+                **a_map,
+                "errmes": _("The relevant plugin is currently not active."),
+            })
+        return wrapper.format_map(a_map)
+
+
+class LogEntryTypeRegistry(EventPluginRegistry):
+    def __init__(self):
+        super().__init__({'action_type': lambda o: getattr(o, 'action_type')})
+
+    def register(self, *objs):
+        for obj in objs:
+            if not isinstance(obj, LogEntryType):
+                raise TypeError('Entries must be derived from LogEntryType')
+
+            if obj.__module__ == LogEntryType.__module__:
+                raise TypeError('Must not register base classes, only derived ones')
+
+        return super().register(*objs)
+
+    def new_from_dict(self, data):
+        """
+        Register multiple instance of a `LogEntryType` class with different `action_type`
+        and plain text strings, as given by the items of the specified data dictionary.
+
+        This method is designed to be used as a decorator as follows:
+
+        .. code-block:: python
+
+            @log_entry_types.new_from_dict({
+                'pretix.event.item.added': _('The product has been created.'),
+                'pretix.event.item.changed': _('The product has been changed.'),
+                # ...
+            })
+            class CoreItemLogEntryType(ItemLogEntryType):
+                # ...
+
+        :param data: action types and descriptions
+                     ``{"some_action_type": "Plain text description", ...}``
+        """
+        def reg(clz):
+            for action_type, plain in data.items():
+                self.register(clz(action_type=action_type, plain=plain))
+            return clz
+        return reg
+
+
+"""
+Registry for LogEntry types.
+
+Each entry in this registry should be an instance of a subclass of ``LogEntryType``.
+They are annotated with their ``action_type`` and the defining ``plugin``.
+"""
+log_entry_types = LogEntryTypeRegistry()
+
+
+class LogEntryType:
+    """
+    Base class for a type of LogEntry, identified by its action_type.
+    """
+
+    def __init__(self, action_type=None, plain=None):
+        if action_type:
+            self.action_type = action_type
+        if plain:
+            self.plain = plain
+
+    def display(self, logentry):
+        """
+        Returns the message to be displayed for a given logentry of this type.
+
+        :return: `str` or `LazyI18nString`
+        """
+        if hasattr(self, 'plain'):
+            plain = str(self.plain)
+            if '{' in plain:
+                data = defaultdict(lambda: '?', logentry.parsed_data)
+                return plain.format_map(data)
+            else:
+                return plain
+
+    def get_object_link_info(self, logentry) -> dict:
+        """
+        Return information to generate a link to the `content_object` of a given log entry.
+
+        Not implemented in the base class, causing the object link to be omitted.
+
+        :return: Dictionary with the keys ``href`` (containing a URL to view/edit the object) and ``val`` (containing the
+                 escaped text for the anchor element)
+        """
+        pass
+
+    def get_object_link(self, logentry):
+        a_map = self.get_object_link_info(logentry)
+        return make_link(a_map, self.object_link_wrapper)
+
+    object_link_wrapper = '{val}'
+
+    def shred_pii(self, logentry):
+        """
+        To be used for shredding personally identified information contained in the data field of a LogEntry of this
+        type.
+        """
+        raise NotImplementedError
+
+
+class EventLogEntryType(LogEntryType):
+    """
+    Base class for any `LogEntry` type whose `content_object` is either an `Event` itself or belongs to a specific `Event`.
+    """
+
+    def get_object_link_info(self, logentry) -> dict:
+        if hasattr(self, 'object_link_viewname') and logentry.content_object:
+            return {
+                'href': reverse(self.object_link_viewname, kwargs={
+                    'event': logentry.event.slug,
+                    'organizer': logentry.event.organizer.slug,
+                    **self.object_link_args(logentry.content_object),
+                }),
+                'val': escape(self.object_link_display_name(logentry.content_object)),
+            }
+
+    def object_link_args(self, content_object):
+        """Return the kwargs for the url used in a link to content_object."""
+        if hasattr(self, 'object_link_argname'):
+            return {self.object_link_argname: content_object.pk}
+        return {}
+
+    def object_link_display_name(self, content_object):
+        """Return the display name to refer to content_object in the user interface."""
+        return str(content_object)
+
+
+class OrderLogEntryType(EventLogEntryType):
+    object_link_wrapper = _('Order {val}')
+    object_link_viewname = 'control:event.order'
+
+    def object_link_args(self, order):
+        return {'code': order.code}
+
+    def object_link_display_name(self, order):
+        return order.code
+
+
+class VoucherLogEntryType(EventLogEntryType):
+    object_link_wrapper = _('Voucher {val}…')
+    object_link_viewname = 'control:event.voucher'
+    object_link_argname = 'voucher'
+
+    def object_link_display_name(self, voucher):
+        if len(voucher.code) > 6:
+            return voucher.code[:6] + "…"
+        return voucher.code
+
+
+class ItemLogEntryType(EventLogEntryType):
+    object_link_wrapper = _('Product {val}')
+    object_link_viewname = 'control:event.item'
+    object_link_argname = 'item'
+
+
+class SubEventLogEntryType(EventLogEntryType):
+    object_link_wrapper = pgettext_lazy('subevent', 'Date {val}')
+    object_link_viewname = 'control:event.subevent'
+    object_link_argname = 'subevent'
+
+
+class QuotaLogEntryType(EventLogEntryType):
+    object_link_wrapper = _('Quota {val}')
+    object_link_viewname = 'control:event.items.quotas.show'
+    object_link_argname = 'quota'
+
+
+class DiscountLogEntryType(EventLogEntryType):
+    object_link_wrapper = _('Discount {val}')
+    object_link_viewname = 'control:event.items.discounts.edit'
+    object_link_argname = 'discount'
+
+
+class ItemCategoryLogEntryType(EventLogEntryType):
+    object_link_wrapper = _('Category {val}')
+    object_link_viewname = 'control:event.items.categories.edit'
+    object_link_argname = 'category'
+
+
+class QuestionLogEntryType(EventLogEntryType):
+    object_link_wrapper = _('Question {val}')
+    object_link_viewname = 'control:event.items.questions.show'
+    object_link_argname = 'question'
+
+
+class TaxRuleLogEntryType(EventLogEntryType):
+    object_link_wrapper = _('Tax rule {val}')
+    object_link_viewname = 'control:event.settings.tax.edit'
+    object_link_argname = 'rule'
+
+
+class NoOpShredderMixin:
+    def shred_pii(self, logentry):
+        pass
+
+
+class ClearDataShredderMixin:
+    def shred_pii(self, logentry):
+        logentry.data = None

src/pretix/base/models/log.py

@@ -33,16 +33,15 @@
 # License for the specific language governing permissions and limitations under the License.
 
 import json
+import logging
 
 from django.contrib.contenttypes.fields import GenericForeignKey
 from django.contrib.contenttypes.models import ContentType
 from django.db import models
-from django.urls import reverse
 from django.utils.functional import cached_property
-from django.utils.html import escape
-from django.utils.translation import gettext_lazy as _, pgettext_lazy
 
-from pretix.base.signals import logentry_object_link
+from pretix.base.logentrytypes import log_entry_types, make_link
+from pretix.base.signals import is_app_active, logentry_object_link
 
 
 class VisibleOnlyManager(models.Manager):
@@ -92,6 +91,10 @@ class LogEntry(models.Model):
         indexes = [models.Index(fields=["datetime", "id"])]
 
     def display(self):
+        log_entry_type, meta = log_entry_types.get(action_type=self.action_type)
+        if log_entry_type:
+            return log_entry_type.display(self)
+
         from ..signals import logentry_display
 
         for receiver, response in logentry_display.send(self.event, logentry=self):
@@ -126,10 +129,18 @@ class LogEntry(models.Model):
     @cached_property
     def display_object(self):
         from . import (
-            Discount, Event, Item, ItemCategory, Order, Question, Quota,
-            SubEvent, TaxRule, Voucher,
+            Discount, Event, Item, Order, Question, Quota, SubEvent, Voucher,
         )
 
+        log_entry_type, meta = log_entry_types.get(action_type=self.action_type)
+        if log_entry_type:
+            link_info = log_entry_type.get_object_link_info(self)
+            if is_app_active(self.event, meta['plugin']):
+                return make_link(link_info, log_entry_type.object_link_wrapper)
+            else:
+                return make_link(link_info, log_entry_type.object_link_wrapper, is_active=False,
+                                 event=self.event, plugin_name=meta['plugin'] and getattr(meta['plugin'], 'name'))
+
         try:
             if self.content_type.model_class() is Event:
                 return ''
@@ -137,110 +148,15 @@ class LogEntry(models.Model):
             co = self.content_object
         except:
             return ''
-        a_map = None
-        a_text = None
 
-        if isinstance(co, Order):
-            a_text = _('Order {val}')
-            a_map = {
-                'href': reverse('control:event.order', kwargs={
-                    'event': self.event.slug,
-                    'organizer': self.event.organizer.slug,
-                    'code': co.code
-                }),
-                'val': escape(co.code),
-            }
-        elif isinstance(co, Voucher):
-            a_text = _('Voucher {val}…')
-            a_map = {
-                'href': reverse('control:event.voucher', kwargs={
-                    'event': self.event.slug,
-                    'organizer': self.event.organizer.slug,
-                    'voucher': co.id
-                }),
-                'val': escape(co.code[:6]),
-            }
-        elif isinstance(co, Item):
-            a_text = _('Product {val}')
-            a_map = {
-                'href': reverse('control:event.item', kwargs={
-                    'event': self.event.slug,
-                    'organizer': self.event.organizer.slug,
-                    'item': co.id
-                }),
-                'val': escape(co.name),
-            }
-        elif isinstance(co, SubEvent):
-            a_text = pgettext_lazy('subevent', 'Date {val}')
-            a_map = {
-                'href': reverse('control:event.subevent', kwargs={
-                    'event': self.event.slug,
-                    'organizer': self.event.organizer.slug,
-                    'subevent': co.id
-                }),
-                'val': escape(str(co))
-            }
-        elif isinstance(co, Quota):
-            a_text = _('Quota {val}')
-            a_map = {
-                'href': reverse('control:event.items.quotas.show', kwargs={
-                    'event': self.event.slug,
-                    'organizer': self.event.organizer.slug,
-                    'quota': co.id
-                }),
-                'val': escape(co.name),
-            }
-        elif isinstance(co, Discount):
-            a_text = _('Discount {val}')
-            a_map = {
-                'href': reverse('control:event.items.discounts.edit', kwargs={
-                    'event': self.event.slug,
-                    'organizer': self.event.organizer.slug,
-                    'discount': co.id
-                }),
-                'val': escape(co.internal_name),
-            }
-        elif isinstance(co, ItemCategory):
-            a_text = _('Category {val}')
-            a_map = {
-                'href': reverse('control:event.items.categories.edit', kwargs={
-                    'event': self.event.slug,
-                    'organizer': self.event.organizer.slug,
-                    'category': co.id
-                }),
-                'val': escape(co.name),
-            }
-        elif isinstance(co, Question):
-            a_text = _('Question {val}')
-            a_map = {
-                'href': reverse('control:event.items.questions.show', kwargs={
-                    'event': self.event.slug,
-                    'organizer': self.event.organizer.slug,
-                    'question': co.id
-                }),
-                'val': escape(co.question),
-            }
-        elif isinstance(co, TaxRule):
-            a_text = _('Tax rule {val}')
-            a_map = {
-                'href': reverse('control:event.settings.tax.edit', kwargs={
-                    'event': self.event.slug,
-                    'organizer': self.event.organizer.slug,
-                    'rule': co.id
-                }),
-                'val': escape(co.name),
-            }
+        for receiver, response in logentry_object_link.send(self.event, logentry=self):
+            if response:
+                return response
 
-        if a_text and a_map:
-            a_map['val'] = '<a href="{href}">{val}</a>'.format_map(a_map)
-            return a_text.format_map(a_map)
-        elif a_text:
-            return a_text
-        else:
-            for receiver, response in logentry_object_link.send(self.event, logentry=self):
-                if response:
-                    return response
-            return ''
+        if isinstance(co, (Order, Voucher, Item, SubEvent, Quota, Discount, Question)):
+            logging.warning("LogEntryType missing or ill-defined: %s", self.action_type)
+
+        return ''
 
     @cached_property
     def parsed_data(self):

src/pretix/base/signals.py

@@ -52,6 +52,50 @@ def _populate_app_cache():
         app_cache[ac.name] = ac
 
 
+def get_defining_app(o):
+    # If sentry packed this in a wrapper, unpack that
+    if "sentry" in o.__module__:
+        o = o.__wrapped__
+
+    # Find the Django application this belongs to
+    searchpath = o.__module__
+
+    # Core modules are always active
+    if any(searchpath.startswith(cm) for cm in settings.CORE_MODULES):
+        return 'CORE'
+
+    if not app_cache:
+        _populate_app_cache()
+
+    while True:
+        app = app_cache.get(searchpath)
+        if "." not in searchpath or app:
+            break
+        searchpath, _ = searchpath.rsplit(".", 1)
+    return app
+
+
+def is_app_active(sender, app):
+    if app == 'CORE':
+        return True
+
+    excluded = settings.PRETIX_PLUGINS_EXCLUDE
+    if sender and app and app.name in sender.get_plugins() and app.name not in excluded:
+        if not hasattr(app, 'compatibility_errors') or not app.compatibility_errors:
+            return True
+    return False
+
+
+def is_receiver_active(sender, receiver):
+    if sender is None:
+        # Send to all events!
+        return True
+
+    app = get_defining_app(receiver)
+
+    return is_app_active(sender, app)
+
+
 class EventPluginSignal(django.dispatch.Signal):
     """
     This is an extension to Django's built-in signals which differs in a way that it sends
@@ -59,33 +103,6 @@ class EventPluginSignal(django.dispatch.Signal):
     Event.
     """
 
-    def _is_active(self, sender, receiver):
-        if sender is None:
-            # Send to all events!
-            return True
-
-        # If sentry packed this in a wrapper, unpack that
-        if "sentry" in receiver.__module__:
-            receiver = receiver.__wrapped__
-
-        # Find the Django application this belongs to
-        searchpath = receiver.__module__
-        core_module = any([searchpath.startswith(cm) for cm in settings.CORE_MODULES])
-        app = None
-        if not core_module:
-            while True:
-                app = app_cache.get(searchpath)
-                if "." not in searchpath or app:
-                    break
-                searchpath, _ = searchpath.rsplit(".", 1)
-
-        # Only fire receivers from active plugins and core modules
-        excluded = settings.PRETIX_PLUGINS_EXCLUDE
-        if core_module or (sender and app and app.name in sender.get_plugins() and app.name not in excluded):
-            if not hasattr(app, 'compatibility_errors') or not app.compatibility_errors:
-                return True
-        return False
-
     def send(self, sender: Event, **named) -> List[Tuple[Callable, Any]]:
         """
         Send signal from sender to all connected receivers that belong to
@@ -104,7 +121,7 @@ class EventPluginSignal(django.dispatch.Signal):
             _populate_app_cache()
 
         for receiver in self._sorted_receivers(sender):
-            if self._is_active(sender, receiver):
+            if is_receiver_active(sender, receiver):
                 response = receiver(signal=self, sender=sender, **named)
                 responses.append((receiver, response))
         return responses
@@ -128,7 +145,7 @@ class EventPluginSignal(django.dispatch.Signal):
             _populate_app_cache()
 
         for receiver in self._sorted_receivers(sender):
-            if self._is_active(sender, receiver):
+            if is_receiver_active(sender, receiver):
                 named[chain_kwarg_name] = response
                 response = receiver(signal=self, sender=sender, **named)
         return response
@@ -155,7 +172,7 @@ class EventPluginSignal(django.dispatch.Signal):
             _populate_app_cache()
 
         for receiver in self._sorted_receivers(sender):
-            if self._is_active(sender, receiver):
+            if is_receiver_active(sender, receiver):
                 try:
                     response = receiver(signal=self, sender=sender, **named)
                 except Exception as err:
@@ -202,6 +219,122 @@ class DeprecatedSignal(django.dispatch.Signal):
         super().connect(receiver, sender=None, weak=True, dispatch_uid=None)
 
 
+class Registry:
+    """
+    A Registry is a collection of objects (entries), annotated with metadata. Entries can be searched and filtered by
+    metadata keys, and metadata is returned as part of the result.
+
+    Entry metadata is generated during registration using to the accessor functions given to the Registry
+    constructor.
+
+    Example:
+
+    .. code-block:: python
+
+        animal_sound_registry = Registry({"animal": lambda s: s.animal})
+
+        @animal_sound_registry.new("dog", "woof")
+        @animal_sound_registry.new("cricket", "chirp")
+        class AnimalSound:
+            def __init__(self, animal, sound):
+                self.animal = animal
+                self.sound = sound
+
+            def make_sound(self):
+                return self.sound
+
+        @animal_sound_registry.new()
+        class CatSound(AnimalSound):
+            def __init__(self):
+                super().__init__(animal="cat", sound=["meow", "meww", "miaou"])
+
+            def make_sound(self):
+                return random.choice(self.sound)
+    """
+
+    def __init__(self, keys):
+        """
+        :param keys: Dictionary with `{key: accessor_function}`
+                     When a new entry is registered, all accessor functions are called with the new entry as parameter.
+                     Their return value is stored as the metadata value for that key.
+        """
+        self.registered_entries = dict()
+        self.keys = keys
+        self.by_key = {key: {} for key in self.keys.keys()}
+
+    def register(self, *objs):
+        """
+        Register one or more entries in this registry.
+
+        Usable as a regular method or as decorator on a class or function. If used on a class, the class type object
+        itself is registered, not an instance of the class. To register an instance, use the ``new`` method.
+
+        .. code-block:: python
+
+            @some_registry.register
+            def my_new_entry(foo):
+              # ...
+        """
+        for obj in objs:
+            if obj in self.registered_entries:
+                raise RuntimeError('Object already registered: {}'.format(obj))
+
+            meta = {k: accessor(obj) for k, accessor in self.keys.items()}
+            tup = (obj, meta)
+            for key, value in meta.items():
+                self.by_key[key][value] = tup
+            self.registered_entries[obj] = meta
+
+        if len(objs) == 1:
+            return objs[0]
+
+    def new(self, *args, **kwargs):
+        """
+        Instantiate the decorated class with the given `*args` and `**kwargs`, and register the instance in this registry.
+        May be used multiple times.
+
+        .. code-block:: python
+
+            @animal_sound_registry.new("meow")
+            @animal_sound_registry.new("woof")
+            class AnimalSound:
+              def __init__(self, sound):
+                # ...
+        """
+        def reg(clz):
+            obj = clz(*args, **kwargs)
+            self.register(obj)
+            return clz
+        return reg
+
+    def get(self, **kwargs):
+        (key, value), = kwargs.items()
+        return self.by_key.get(key).get(value, (None, None))
+
+    def filter(self, **kwargs):
+        return (
+            (entry, meta)
+            for entry, meta in self.registered_entries.items()
+            if all(value == meta[key] for key, value in kwargs.items())
+        )
+
+
+class EventPluginRegistry(Registry):
+    """
+    A Registry which automatically annotates entries with a "plugin" key, specifying which plugin
+    the entry is defined in. This allows the consumer of entries to determine whether an entry is
+    enabled for a given event, or filter only for entries defined by enabled plugins.
+
+    .. code-block:: python
+
+        logtype, meta = my_registry.find(action_type="foo.bar.baz")
+        # meta["plugin"] contains the django app name of the defining plugin
+    """
+
+    def __init__(self, keys):
+        super().__init__({"plugin": lambda o: get_defining_app(o), **keys})
+
+
 event_live_issues = EventPluginSignal()
 """
 This signal is sent out to determine whether an event can be taken live. If you want to
@@ -507,41 +640,16 @@ logentry_display = EventPluginSignal()
 """
 Arguments: ``logentry``
 
-To display an instance of the ``LogEntry`` model to a human user,
-``pretix.base.signals.logentry_display`` will be sent out with a ``logentry`` argument.
-
-The first received response that is not ``None`` will be used to display the log entry
-to the user. The receivers are expected to return plain text.
-
-As with all event-plugin signals, the ``sender`` keyword argument will contain the event.
+**DEPRECTATION:** Please do not use this signal for new LogEntry types. Use the log_entry_types
+registry instead, as described in https://docs.pretix.eu/en/latest/development/implementation/logging.html
 """
 
 logentry_object_link = EventPluginSignal()
 """
 Arguments: ``logentry``
 
-To display the relationship of an instance of the ``LogEntry`` model to another model
-to a human user, ``pretix.base.signals.logentry_object_link`` will be sent out with a
-``logentry`` argument.
-
-The first received response that is not ``None`` will be used to display the related object
-to the user. The receivers are expected to return a HTML link. The internal implementation
-builds the links like this::
-
-    a_text = _('Tax rule {val}')
-    a_map = {
-        'href': reverse('control:event.settings.tax.edit', kwargs={
-            'event': sender.slug,
-            'organizer': sender.organizer.slug,
-            'rule': logentry.content_object.id
-        }),
-        'val': escape(logentry.content_object.name),
-    }
-    a_map['val'] = '<a href="{href}">{val}</a>'.format_map(a_map)
-    return a_text.format_map(a_map)
-
-Make sure that any user content in the HTML code you return is properly escaped!
-As with all event-plugin signals, the ``sender`` keyword argument will contain the event.
+**DEPRECTATION:** Please do not use this signal for new LogEntry types. Use the log_entry_types
+registry instead, as described in https://docs.pretix.eu/en/latest/development/implementation/logging.html
 """
 
 requiredaction_display = EventPluginSignal()

src/pretix/control/logdisplay.py

@@ -47,12 +47,20 @@ from django.utils.safestring import mark_safe
 from django.utils.translation import gettext_lazy as _, pgettext_lazy
 from i18nfield.strings import LazyI18nString
 
+from pretix.base.logentrytypes import (
+    DiscountLogEntryType, EventLogEntryType, ItemCategoryLogEntryType,
+    ItemLogEntryType, LogEntryType, OrderLogEntryType, QuestionLogEntryType,
+    QuotaLogEntryType, TaxRuleLogEntryType, VoucherLogEntryType,
+    log_entry_types,
+)
 from pretix.base.models import (
     Checkin, CheckinList, Event, ItemVariation, LogEntry, OrderPosition,
     TaxRule,
 )
 from pretix.base.models.orders import PrintLog
-from pretix.base.signals import logentry_display, orderposition_blocked_display
+from pretix.base.signals import (
+    app_cache, logentry_display, orderposition_blocked_display,
+)
 from pretix.base.templatetags.money import money_filter
 
 OVERVIEW_BANLIST = [
@@ -329,278 +337,6 @@ def _display_checkin(event, logentry):
 
 @receiver(signal=logentry_display, dispatch_uid="pretixcontrol_logentry_display")
 def pretixcontrol_logentry_display(sender: Event, logentry: LogEntry, **kwargs):
-    plains = {
-        'pretix.object.cloned': _('This object has been created by cloning.'),
-        'pretix.organizer.changed': _('The organizer has been changed.'),
-        'pretix.organizer.settings': _('The organizer settings have been changed.'),
-        'pretix.organizer.footerlinks.changed': _('The footer links have been changed.'),
-        'pretix.organizer.export.schedule.added': _('A scheduled export has been added.'),
-        'pretix.organizer.export.schedule.changed': _('A scheduled export has been changed.'),
-        'pretix.organizer.export.schedule.deleted': _('A scheduled export has been deleted.'),
-        'pretix.organizer.export.schedule.executed': _('A scheduled export has been executed.'),
-        'pretix.organizer.export.schedule.failed': _('A scheduled export has failed: {reason}.'),
-        'pretix.giftcards.acceptance.added': _('Gift card acceptance for another organizer has been added.'),
-        'pretix.giftcards.acceptance.removed': _('Gift card acceptance for another organizer has been removed.'),
-        'pretix.giftcards.acceptance.acceptor.invited': _('A new gift card acceptor has been invited.'),
-        'pretix.giftcards.acceptance.acceptor.removed': _('A gift card acceptor has been removed.'),
-        'pretix.giftcards.acceptance.issuer.removed': _('A gift card issuer has been removed or declined.'),
-        'pretix.giftcards.acceptance.issuer.accepted': _('A new gift card issuer has been accepted.'),
-        'pretix.webhook.created': _('The webhook has been created.'),
-        'pretix.webhook.changed': _('The webhook has been changed.'),
-        'pretix.webhook.retries.expedited': _('The webhook call retry jobs have been manually expedited.'),
-        'pretix.webhook.retries.dropped': _('The webhook call retry jobs have been dropped.'),
-        'pretix.ssoprovider.created': _('The SSO provider has been created.'),
-        'pretix.ssoprovider.changed': _('The SSO provider has been changed.'),
-        'pretix.ssoprovider.deleted': _('The SSO provider has been deleted.'),
-        'pretix.ssoclient.created': _('The SSO client has been created.'),
-        'pretix.ssoclient.changed': _('The SSO client has been changed.'),
-        'pretix.ssoclient.deleted': _('The SSO client has been deleted.'),
-        'pretix.membershiptype.created': _('The membership type has been created.'),
-        'pretix.membershiptype.changed': _('The membership type has been changed.'),
-        'pretix.membershiptype.deleted': _('The membership type has been deleted.'),
-        'pretix.saleschannel.created': _('The sales channel has been created.'),
-        'pretix.saleschannel.changed': _('The sales channel has been changed.'),
-        'pretix.saleschannel.deleted': _('The sales channel has been deleted.'),
-        'pretix.customer.created': _('The account has been created.'),
-        'pretix.customer.changed': _('The account has been changed.'),
-        'pretix.customer.membership.created': _('A membership for this account has been added.'),
-        'pretix.customer.membership.changed': _('A membership of this account has been changed.'),
-        'pretix.customer.membership.deleted': _('A membership of this account has been deleted.'),
-        'pretix.customer.anonymized': _('The account has been disabled and anonymized.'),
-        'pretix.customer.password.resetrequested': _('A new password has been requested.'),
-        'pretix.customer.password.set': _('A new password has been set.'),
-        'pretix.reusable_medium.created': _('The reusable medium has been created.'),
-        'pretix.reusable_medium.created.auto': _('The reusable medium has been created automatically.'),
-        'pretix.reusable_medium.changed': _('The reusable medium has been changed.'),
-        'pretix.reusable_medium.linked_orderposition.changed': _('The medium has been connected to a new ticket.'),
-        'pretix.reusable_medium.linked_giftcard.changed': _('The medium has been connected to a new gift card.'),
-        'pretix.email.error': _('Sending of an email has failed.'),
-        'pretix.event.comment': _('The event\'s internal comment has been updated.'),
-        'pretix.event.canceled': _('The event has been canceled.'),
-        'pretix.event.deleted': _('An event has been deleted.'),
-        'pretix.event.shredder.started': _('A removal process for personal data has been started.'),
-        'pretix.event.shredder.completed': _('A removal process for personal data has been completed.'),
-        'pretix.event.order.modified': _('The order details have been changed.'),
-        'pretix.event.order.unpaid': _('The order has been marked as unpaid.'),
-        'pretix.event.order.secret.changed': _('The order\'s secret has been changed.'),
-        'pretix.event.order.expirychanged': _('The order\'s expiry date has been changed.'),
-        'pretix.event.order.valid_if_pending.set': _('The order has been set to be usable before it is paid.'),
-        'pretix.event.order.valid_if_pending.unset': _('The order has been set to require payment before use.'),
-        'pretix.event.order.expired': _('The order has been marked as expired.'),
-        'pretix.event.order.paid': _('The order has been marked as paid.'),
-        'pretix.event.order.cancellationrequest.deleted': _('The cancellation request has been deleted.'),
-        'pretix.event.order.refunded': _('The order has been refunded.'),
-        'pretix.event.order.reactivated': _('The order has been reactivated.'),
-        'pretix.event.order.deleted': _('The test mode order {code} has been deleted.'),
-        'pretix.event.order.placed': _('The order has been created.'),
-        'pretix.event.order.placed.require_approval': _('The order requires approval before it can continue to be processed.'),
-        'pretix.event.order.approved': _('The order has been approved.'),
-        'pretix.event.order.denied': _('The order has been denied (comment: "{comment}").'),
-        'pretix.event.order.contact.changed': _('The email address has been changed from "{old_email}" '
-                                                'to "{new_email}".'),
-        'pretix.event.order.contact.confirmed': _('The email address has been confirmed to be working (the user clicked on a link '
-                                                  'in the email for the first time).'),
-        'pretix.event.order.phone.changed': _('The phone number has been changed from "{old_phone}" '
-                                              'to "{new_phone}".'),
-        'pretix.event.order.customer.changed': _('The customer account has been changed.'),
-        'pretix.event.order.locale.changed': _('The order locale has been changed.'),
-        'pretix.event.order.invoice.generated': _('The invoice has been generated.'),
-        'pretix.event.order.invoice.regenerated': _('The invoice has been regenerated.'),
-        'pretix.event.order.invoice.reissued': _('The invoice has been reissued.'),
-        'pretix.event.order.comment': _('The order\'s internal comment has been updated.'),
-        'pretix.event.order.custom_followup_at': _('The order\'s follow-up date has been updated.'),
-        'pretix.event.order.checkin_attention': _('The order\'s flag to require attention at check-in has been '
-                                                  'toggled.'),
-        'pretix.event.order.checkin_text': _('The order\'s check-in text has been changed.'),
-        'pretix.event.order.pretix.event.order.valid_if_pending': _('The order\'s flag to be considered valid even if '
-                                                                    'unpaid has been toggled.'),
-        'pretix.event.order.payment.changed': _('A new payment {local_id} has been started instead of the previous one.'),
-        'pretix.event.order.email.sent': _('An unidentified type email has been sent.'),
-        'pretix.event.order.email.error': _('Sending of an email has failed.'),
-        'pretix.event.order.email.attachments.skipped': _('The email has been sent without attached tickets since they '
-                                                          'would have been too large to be likely to arrive.'),
-        'pretix.event.order.email.custom_sent': _('A custom email has been sent.'),
-        'pretix.event.order.position.email.custom_sent': _('A custom email has been sent to an attendee.'),
-        'pretix.event.order.email.download_reminder_sent': _('An email has been sent with a reminder that the ticket '
-                                                             'is available for download.'),
-        'pretix.event.order.email.expire_warning_sent': _('An email has been sent with a warning that the order is about '
-                                                          'to expire.'),
-        'pretix.event.order.email.order_canceled': _('An email has been sent to notify the user that the order has been canceled.'),
-        'pretix.event.order.email.event_canceled': _('An email has been sent to notify the user that the event has '
-                                                     'been canceled.'),
-        'pretix.event.order.email.order_changed': _('An email has been sent to notify the user that the order has been changed.'),
-        'pretix.event.order.email.order_free': _('An email has been sent to notify the user that the order has been received.'),
-        'pretix.event.order.email.order_paid': _('An email has been sent to notify the user that payment has been received.'),
-        'pretix.event.order.email.order_denied': _('An email has been sent to notify the user that the order has been denied.'),
-        'pretix.event.order.email.order_approved': _('An email has been sent to notify the user that the order has '
-                                                     'been approved.'),
-        'pretix.event.order.email.order_placed': _('An email has been sent to notify the user that the order has been received and requires payment.'),
-        'pretix.event.order.email.order_placed_require_approval': _('An email has been sent to notify the user that '
-                                                                    'the order has been received and requires '
-                                                                    'approval.'),
-        'pretix.event.order.email.resend': _('An email with a link to the order detail page has been resent to the user.'),
-        'pretix.event.order.email.payment_failed': _('An email has been sent to notify the user that the payment failed.'),
-        'pretix.event.order.payment.confirmed': _('Payment {local_id} has been confirmed.'),
-        'pretix.event.order.payment.canceled': _('Payment {local_id} has been canceled.'),
-        'pretix.event.order.payment.canceled.failed': _('Canceling payment {local_id} has failed.'),
-        'pretix.event.order.payment.started': _('Payment {local_id} has been started.'),
-        'pretix.event.order.payment.failed': _('Payment {local_id} has failed.'),
-        'pretix.event.order.quotaexceeded': _('The order could not be marked as paid: {message}'),
-        'pretix.event.order.overpaid': _('The order has been overpaid.'),
-        'pretix.event.order.refund.created': _('Refund {local_id} has been created.'),
-        'pretix.event.order.refund.created.externally': _('Refund {local_id} has been created by an external entity.'),
-        'pretix.event.order.refund.requested': _('The customer requested you to issue a refund.'),
-        'pretix.event.order.refund.done': _('Refund {local_id} has been completed.'),
-        'pretix.event.order.refund.canceled': _('Refund {local_id} has been canceled.'),
-        'pretix.event.order.refund.failed': _('Refund {local_id} has failed.'),
-        'pretix.event.export.schedule.added': _('A scheduled export has been added.'),
-        'pretix.event.export.schedule.changed': _('A scheduled export has been changed.'),
-        'pretix.event.export.schedule.deleted': _('A scheduled export has been deleted.'),
-        'pretix.event.export.schedule.executed': _('A scheduled export has been executed.'),
-        'pretix.event.export.schedule.failed': _('A scheduled export has failed: {reason}.'),
-        'pretix.control.auth.user.created': _('The user has been created.'),
-        'pretix.control.auth.user.new_source': _('A first login using {agent_type} on {os_type} from {country} has '
-                                                 'been detected.'),
-        'pretix.user.settings.2fa.enabled': _('Two-factor authentication has been enabled.'),
-        'pretix.user.settings.2fa.disabled': _('Two-factor authentication has been disabled.'),
-        'pretix.user.settings.2fa.regenemergency': _('Your two-factor emergency codes have been regenerated.'),
-        'pretix.user.settings.2fa.emergency': _('A two-factor emergency code has been generated.'),
-        'pretix.user.settings.2fa.device.added': _('A new two-factor authentication device "{name}" has been added to '
-                                                   'your account.'),
-        'pretix.user.settings.2fa.device.deleted': _('The two-factor authentication device "{name}" has been removed '
-                                                     'from your account.'),
-        'pretix.user.settings.notifications.enabled': _('Notifications have been enabled.'),
-        'pretix.user.settings.notifications.disabled': _('Notifications have been disabled.'),
-        'pretix.user.settings.notifications.changed': _('Your notification settings have been changed.'),
-        'pretix.user.anonymized': _('This user has been anonymized.'),
-        'pretix.user.oauth.authorized': _('The application "{application_name}" has been authorized to access your '
-                                          'account.'),
-        'pretix.control.auth.user.forgot_password.mail_sent': _('Password reset mail sent.'),
-        'pretix.control.auth.user.forgot_password.recovered': _('The password has been reset.'),
-        'pretix.control.auth.user.forgot_password.denied.repeated': _('A repeated password reset has been denied, as '
-                                                                      'the last request was less than 24 hours ago.'),
-        'pretix.organizer.deleted': _('The organizer "{name}" has been deleted.'),
-        'pretix.voucher.added': _('The voucher has been created.'),
-        'pretix.voucher.sent': _('The voucher has been sent to {recipient}.'),
-        'pretix.voucher.added.waitinglist': _('The voucher has been created and sent to a person on the waiting list.'),
-        'pretix.voucher.expired.waitinglist': _('The voucher has been set to expire because the recipient removed themselves from the waiting list.'),
-        'pretix.voucher.changed': _('The voucher has been changed.'),
-        'pretix.voucher.deleted': _('The voucher has been deleted.'),
-        'pretix.voucher.redeemed': _('The voucher has been redeemed in order {order_code}.'),
-        'pretix.event.item.added': _('The product has been created.'),
-        'pretix.event.item.changed': _('The product has been changed.'),
-        'pretix.event.item.reordered': _('The product has been reordered.'),
-        'pretix.event.item.deleted': _('The product has been deleted.'),
-        'pretix.event.item.variation.added': _('The variation "{value}" has been created.'),
-        'pretix.event.item.variation.deleted': _('The variation "{value}" has been deleted.'),
-        'pretix.event.item.variation.changed': _('The variation "{value}" has been changed.'),
-        'pretix.event.item.addons.added': _('An add-on has been added to this product.'),
-        'pretix.event.item.addons.removed': _('An add-on has been removed from this product.'),
-        'pretix.event.item.addons.changed': _('An add-on has been changed on this product.'),
-        'pretix.event.item.bundles.added': _('A bundled item has been added to this product.'),
-        'pretix.event.item.bundles.removed': _('A bundled item has been removed from this product.'),
-        'pretix.event.item.bundles.changed': _('A bundled item has been changed on this product.'),
-        'pretix.event.item_meta_property.added': _('A meta property has been added to this event.'),
-        'pretix.event.item_meta_property.deleted': _('A meta property has been removed from this event.'),
-        'pretix.event.item_meta_property.changed': _('A meta property has been changed on this event.'),
-        'pretix.event.quota.added': _('The quota has been added.'),
-        'pretix.event.quota.deleted': _('The quota has been deleted.'),
-        'pretix.event.quota.changed': _('The quota has been changed.'),
-        'pretix.event.quota.closed': _('The quota has closed.'),
-        'pretix.event.quota.opened': _('The quota has been re-opened.'),
-        'pretix.event.category.added': _('The category has been added.'),
-        'pretix.event.category.deleted': _('The category has been deleted.'),
-        'pretix.event.category.changed': _('The category has been changed.'),
-        'pretix.event.category.reordered': _('The category has been reordered.'),
-        'pretix.event.question.added': _('The question has been added.'),
-        'pretix.event.question.deleted': _('The question has been deleted.'),
-        'pretix.event.question.changed': _('The question has been changed.'),
-        'pretix.event.question.reordered': _('The question has been reordered.'),
-        'pretix.event.discount.added': _('The discount has been added.'),
-        'pretix.event.discount.deleted': _('The discount has been deleted.'),
-        'pretix.event.discount.changed': _('The discount has been changed.'),
-        'pretix.event.taxrule.added': _('The tax rule has been added.'),
-        'pretix.event.taxrule.deleted': _('The tax rule has been deleted.'),
-        'pretix.event.taxrule.changed': _('The tax rule has been changed.'),
-        'pretix.event.checkinlist.added': _('The check-in list has been added.'),
-        'pretix.event.checkinlist.deleted': _('The check-in list has been deleted.'),
-        'pretix.event.checkinlists.deleted': _('The check-in list has been deleted.'),  # backwards compatibility
-        'pretix.event.checkinlist.changed': _('The check-in list has been changed.'),
-        'pretix.event.settings': _('The event settings have been changed.'),
-        'pretix.event.tickets.settings': _('The ticket download settings have been changed.'),
-        'pretix.event.plugins.enabled': _('A plugin has been enabled.'),
-        'pretix.event.plugins.disabled': _('A plugin has been disabled.'),
-        'pretix.event.live.activated': _('The shop has been taken live.'),
-        'pretix.event.live.deactivated': _('The shop has been taken offline.'),
-        'pretix.event.testmode.activated': _('The shop has been taken into test mode.'),
-        'pretix.event.testmode.deactivated': _('The test mode has been disabled.'),
-        'pretix.event.added': _('The event has been created.'),
-        'pretix.event.changed': _('The event details have been changed.'),
-        'pretix.event.footerlinks.changed': _('The footer links have been changed.'),
-        'pretix.event.question.option.added': _('An answer option has been added to the question.'),
-        'pretix.event.question.option.deleted': _('An answer option has been removed from the question.'),
-        'pretix.event.question.option.changed': _('An answer option has been changed.'),
-        'pretix.event.permissions.added': _('A user has been added to the event team.'),
-        'pretix.event.permissions.invited': _('A user has been invited to the event team.'),
-        'pretix.event.permissions.changed': _('A user\'s permissions have been changed.'),
-        'pretix.event.permissions.deleted': _('A user has been removed from the event team.'),
-        'pretix.waitinglist.voucher': _('A voucher has been sent to a person on the waiting list.'),  # legacy
-        'pretix.event.orders.waitinglist.voucher_assigned': _('A voucher has been sent to a person on the waiting list.'),
-        'pretix.event.orders.waitinglist.deleted': _('An entry has been removed from the waiting list.'),
-        'pretix.event.order.waitinglist.transferred': _('An entry has been transferred to another waiting list.'),  # legacy
-        'pretix.event.orders.waitinglist.changed': _('An entry has been changed on the waiting list.'),
-        'pretix.event.orders.waitinglist.added': _('An entry has been added to the waiting list.'),
-        'pretix.team.created': _('The team has been created.'),
-        'pretix.team.changed': _('The team settings have been changed.'),
-        'pretix.team.deleted': _('The team has been deleted.'),
-        'pretix.gate.created': _('The gate has been created.'),
-        'pretix.gate.changed': _('The gate has been changed.'),
-        'pretix.gate.deleted': _('The gate has been deleted.'),
-        'pretix.subevent.deleted': pgettext_lazy('subevent', 'The event date has been deleted.'),
-        'pretix.subevent.canceled': pgettext_lazy('subevent', 'The event date has been canceled.'),
-        'pretix.subevent.changed': pgettext_lazy('subevent', 'The event date has been changed.'),
-        'pretix.subevent.added': pgettext_lazy('subevent', 'The event date has been created.'),
-        'pretix.subevent.quota.added': pgettext_lazy('subevent', 'A quota has been added to the event date.'),
-        'pretix.subevent.quota.changed': pgettext_lazy('subevent', 'A quota has been changed on the event date.'),
-        'pretix.subevent.quota.deleted': pgettext_lazy('subevent', 'A quota has been removed from the event date.'),
-        'pretix.device.created': _('The device has been created.'),
-        'pretix.device.changed': _('The device has been changed.'),
-        'pretix.device.revoked': _('Access of the device has been revoked.'),
-        'pretix.device.initialized': _('The device has been initialized.'),
-        'pretix.device.keyroll': _('The access token of the device has been regenerated.'),
-        'pretix.device.updated': _('The device has notified the server of an hardware or software update.'),
-        'pretix.giftcards.created': _('The gift card has been created.'),
-        'pretix.giftcards.modified': _('The gift card has been changed.'),
-        'pretix.giftcards.transaction.manual': _('A manual transaction has been performed.'),
-    }
-
-    data = json.loads(logentry.data)
-
-    if logentry.action_type.startswith('pretix.event.item.variation'):
-        if 'value' not in data:
-            # Backwards compatibility
-            var = ItemVariation.objects.filter(id=data['id']).first()
-            if var:
-                data['value'] = str(var.value)
-            else:
-                data['value'] = '?'
-        else:
-            data['value'] = LazyI18nString(data['value'])
-
-    if logentry.action_type == "pretix.voucher.redeemed":
-        data = defaultdict(lambda: '?', data)
-        url = reverse('control:event.order', kwargs={
-            'event': logentry.event.slug,
-            'organizer': logentry.event.organizer.slug,
-            'code': data['order_code']
-        })
-        return mark_safe(plains[logentry.action_type].format(
-            order_code='<a href="{}">{}</a>'.format(url, data['order_code']),
-        ))
-
-    if logentry.action_type in plains:
-        data = defaultdict(lambda: '?', data)
-        return plains[logentry.action_type].format_map(data)
 
     if logentry.action_type.startswith('pretix.event.order.changed'):
         return _display_order_changed(sender, logentry)
@@ -624,16 +360,16 @@ def pretixcontrol_logentry_display(sender: Event, logentry: LogEntry, **kwargs):
             return _('The order has been canceled.')
 
     if logentry.action_type in ('pretix.control.views.checkin.reverted', 'pretix.event.checkin.reverted'):
-        if 'list' in data:
+        if 'list' in logentry.parsed_data:
             try:
-                checkin_list = sender.checkin_lists.get(pk=data.get('list')).name
+                checkin_list = sender.checkin_lists.get(pk=logentry.parsed_data.get('list')).name
             except CheckinList.DoesNotExist:
                 checkin_list = _("(unknown)")
         else:
             checkin_list = _("(unknown)")
 
         return _('The check-in of position #{posid} on list "{list}" has been reverted.').format(
-            posid=data.get('positionid'),
+            posid=logentry.parsed_data.get('positionid'),
             list=checkin_list,
         )
 
@@ -642,83 +378,14 @@ def pretixcontrol_logentry_display(sender: Event, logentry: LogEntry, **kwargs):
 
     if logentry.action_type == 'pretix.event.order.print':
         return _('Position #{posid} has been printed at {datetime} with type "{type}".').format(
-            posid=data.get('positionid'),
+            posid=logentry.parsed_data.get('positionid'),
             datetime=date_format(
-                dateutil.parser.parse(data["datetime"]).astimezone(sender.timezone),
+                dateutil.parser.parse(logentry.parsed_data["datetime"]).astimezone(sender.timezone),
                 "SHORT_DATETIME_FORMAT"
             ),
-            type=dict(PrintLog.PRINT_TYPES)[data["type"]],
+            type=dict(PrintLog.PRINT_TYPES)[logentry.parsed_data["type"]],
         )
 
-    if logentry.action_type == 'pretix.control.views.checkin':
-        # deprecated
-        dt = dateutil.parser.parse(data.get('datetime'))
-        tz = sender.timezone
-        dt_formatted = date_format(dt.astimezone(tz), "SHORT_DATETIME_FORMAT")
-        if 'list' in data:
-            try:
-                checkin_list = sender.checkin_lists.get(pk=data.get('list')).name
-            except CheckinList.DoesNotExist:
-                checkin_list = _("(unknown)")
-        else:
-            checkin_list = _("(unknown)")
-
-        if data.get('first'):
-            return _('Position #{posid} has been checked in manually at {datetime} on list "{list}".').format(
-                posid=data.get('positionid'),
-                datetime=dt_formatted,
-                list=checkin_list,
-            )
-        return _('Position #{posid} has been checked in again at {datetime} on list "{list}".').format(
-            posid=data.get('positionid'),
-            datetime=dt_formatted,
-            list=checkin_list
-        )
-
-    if logentry.action_type == 'pretix.team.member.added':
-        return _('{user} has been added to the team.').format(user=data.get('email'))
-
-    if logentry.action_type == 'pretix.team.member.removed':
-        return _('{user} has been removed from the team.').format(user=data.get('email'))
-
-    if logentry.action_type == 'pretix.team.member.joined':
-        return _('{user} has joined the team using the invite sent to {email}.').format(
-            user=data.get('email'), email=data.get('invite_email')
-        )
-
-    if logentry.action_type == 'pretix.team.invite.created':
-        return _('{user} has been invited to the team.').format(user=data.get('email'))
-
-    if logentry.action_type == 'pretix.team.invite.resent':
-        return _('Invite for {user} has been resent.').format(user=data.get('email'))
-
-    if logentry.action_type == 'pretix.team.invite.deleted':
-        return _('The invite for {user} has been revoked.').format(user=data.get('email'))
-
-    if logentry.action_type == 'pretix.team.token.created':
-        return _('The token "{name}" has been created.').format(name=data.get('name'))
-
-    if logentry.action_type == 'pretix.team.token.deleted':
-        return _('The token "{name}" has been revoked.').format(name=data.get('name'))
-
-    if logentry.action_type == 'pretix.user.settings.changed':
-        text = str(_('Your account settings have been changed.'))
-        if 'email' in data:
-            text = text + ' ' + str(_('Your email address has been changed to {email}.').format(email=data['email']))
-        if 'new_pw' in data:
-            text = text + ' ' + str(_('Your password has been changed.'))
-        if data.get('is_active') is True:
-            text = text + ' ' + str(_('Your account has been enabled.'))
-        elif data.get('is_active') is False:
-            text = text + ' ' + str(_('Your account has been disabled.'))
-        return text
-
-    if logentry.action_type == 'pretix.control.auth.user.impersonated':
-        return str(_('You impersonated {}.')).format(data['other_email'])
-
-    if logentry.action_type == 'pretix.control.auth.user.impersonate_stopped':
-        return str(_('You stopped impersonating {}.')).format(data['other_email'])
-
 
 @receiver(signal=orderposition_blocked_display, dispatch_uid="pretixcontrol_orderposition_blocked_display")
 def pretixcontrol_orderposition_blocked_display(sender: Event, orderposition, block_name, **kwargs):
@@ -726,3 +393,459 @@ def pretixcontrol_orderposition_blocked_display(sender: Event, orderposition, bl
         return _('Blocked manually')
     elif block_name.startswith('api:'):
         return _('Blocked because of an API integration')
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.order.modified': _('The order details have been changed.'),
+    'pretix.event.order.unpaid': _('The order has been marked as unpaid.'),
+    'pretix.event.order.secret.changed': _('The order\'s secret has been changed.'),
+    'pretix.event.order.expirychanged': _('The order\'s expiry date has been changed.'),
+    'pretix.event.order.valid_if_pending.set': _('The order has been set to be usable before it is paid.'),
+    'pretix.event.order.valid_if_pending.unset': _('The order has been set to require payment before use.'),
+    'pretix.event.order.expired': _('The order has been marked as expired.'),
+    'pretix.event.order.paid': _('The order has been marked as paid.'),
+    'pretix.event.order.cancellationrequest.deleted': _('The cancellation request has been deleted.'),
+    'pretix.event.order.refunded': _('The order has been refunded.'),
+    'pretix.event.order.reactivated': _('The order has been reactivated.'),
+    'pretix.event.order.deleted': _('The test mode order {code} has been deleted.'),
+    'pretix.event.order.placed': _('The order has been created.'),
+    'pretix.event.order.placed.require_approval': _(
+        'The order requires approval before it can continue to be processed.'),
+    'pretix.event.order.approved': _('The order has been approved.'),
+    'pretix.event.order.denied': _('The order has been denied (comment: "{comment}").'),
+    'pretix.event.order.contact.changed': _('The email address has been changed from "{old_email}" '
+                                            'to "{new_email}".'),
+    'pretix.event.order.contact.confirmed': _(
+        'The email address has been confirmed to be working (the user clicked on a link '
+        'in the email for the first time).'),
+    'pretix.event.order.phone.changed': _('The phone number has been changed from "{old_phone}" '
+                                          'to "{new_phone}".'),
+    'pretix.event.order.customer.changed': _('The customer account has been changed.'),
+    'pretix.event.order.locale.changed': _('The order locale has been changed.'),
+    'pretix.event.order.invoice.generated': _('The invoice has been generated.'),
+    'pretix.event.order.invoice.regenerated': _('The invoice has been regenerated.'),
+    'pretix.event.order.invoice.reissued': _('The invoice has been reissued.'),
+    'pretix.event.order.comment': _('The order\'s internal comment has been updated.'),
+    'pretix.event.order.custom_followup_at': _('The order\'s follow-up date has been updated.'),
+    'pretix.event.order.checkin_attention': _('The order\'s flag to require attention at check-in has been '
+                                              'toggled.'),
+    'pretix.event.order.checkin_text': _('The order\'s check-in text has been changed.'),
+    'pretix.event.order.pretix.event.order.valid_if_pending': _('The order\'s flag to be considered valid even if '
+                                                                'unpaid has been toggled.'),
+    'pretix.event.order.payment.changed': _('A new payment {local_id} has been started instead of the previous one.'),
+    'pretix.event.order.email.sent': _('An unidentified type email has been sent.'),
+    'pretix.event.order.email.error': _('Sending of an email has failed.'),
+    'pretix.event.order.email.attachments.skipped': _('The email has been sent without attached tickets since they '
+                                                      'would have been too large to be likely to arrive.'),
+    'pretix.event.order.email.custom_sent': _('A custom email has been sent.'),
+    'pretix.event.order.position.email.custom_sent': _('A custom email has been sent to an attendee.'),
+    'pretix.event.order.email.download_reminder_sent': _('An email has been sent with a reminder that the ticket '
+                                                         'is available for download.'),
+    'pretix.event.order.email.expire_warning_sent': _('An email has been sent with a warning that the order is about '
+                                                      'to expire.'),
+    'pretix.event.order.email.order_canceled': _(
+        'An email has been sent to notify the user that the order has been canceled.'),
+    'pretix.event.order.email.event_canceled': _('An email has been sent to notify the user that the event has '
+                                                 'been canceled.'),
+    'pretix.event.order.email.order_changed': _(
+        'An email has been sent to notify the user that the order has been changed.'),
+    'pretix.event.order.email.order_free': _(
+        'An email has been sent to notify the user that the order has been received.'),
+    'pretix.event.order.email.order_paid': _(
+        'An email has been sent to notify the user that payment has been received.'),
+    'pretix.event.order.email.order_denied': _(
+        'An email has been sent to notify the user that the order has been denied.'),
+    'pretix.event.order.email.order_approved': _('An email has been sent to notify the user that the order has '
+                                                 'been approved.'),
+    'pretix.event.order.email.order_placed': _(
+        'An email has been sent to notify the user that the order has been received and requires payment.'),
+    'pretix.event.order.email.order_placed_require_approval': _('An email has been sent to notify the user that '
+                                                                'the order has been received and requires '
+                                                                'approval.'),
+    'pretix.event.order.email.resend': _('An email with a link to the order detail page has been resent to the user.'),
+    'pretix.event.order.email.payment_failed': _('An email has been sent to notify the user that the payment failed.'),
+})
+class CoreOrderLogEntryType(OrderLogEntryType):
+    pass
+
+
+@log_entry_types.new_from_dict({
+    'pretix.voucher.added': _('The voucher has been created.'),
+    'pretix.voucher.sent': _('The voucher has been sent to {recipient}.'),
+    'pretix.voucher.added.waitinglist': _('The voucher has been created and sent to a person on the waiting list.'),
+    'pretix.voucher.expired.waitinglist': _(
+        'The voucher has been set to expire because the recipient removed themselves from the waiting list.'),
+    'pretix.voucher.changed': _('The voucher has been changed.'),
+    'pretix.voucher.deleted': _('The voucher has been deleted.'),
+})
+class CoreVoucherLogEntryType(VoucherLogEntryType):
+    pass
+
+
+@log_entry_types.new()
+class VoucherRedeemedLogEntryType(VoucherLogEntryType):
+    action_type = 'pretix.voucher.redeemed'
+    plain = _('The voucher has been redeemed in order {order_code}.')
+
+    def display(self, logentry):
+        data = json.loads(logentry.data)
+        data = defaultdict(lambda: '?', data)
+        url = reverse('control:event.order', kwargs={
+            'event': logentry.event.slug,
+            'organizer': logentry.event.organizer.slug,
+            'code': data['order_code']
+        })
+        return mark_safe(self.plain.format(
+            order_code='<a href="{}">{}</a>'.format(url, data['order_code']),
+        ))
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.category.added': _('The category has been added.'),
+    'pretix.event.category.deleted': _('The category has been deleted.'),
+    'pretix.event.category.changed': _('The category has been changed.'),
+    'pretix.event.category.reordered': _('The category has been reordered.'),
+})
+class CoreItemCategoryLogEntryType(ItemCategoryLogEntryType):
+    pass
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.taxrule.added': _('The tax rule has been added.'),
+    'pretix.event.taxrule.deleted': _('The tax rule has been deleted.'),
+    'pretix.event.taxrule.changed': _('The tax rule has been changed.'),
+})
+class CoreTaxRuleLogEntryType(TaxRuleLogEntryType):
+    pass
+
+
+class TeamMembershipLogEntryType(LogEntryType):
+    def display(self, logentry):
+        return self.plain.format(user=logentry.parsed_data.get('email'))
+
+
+@log_entry_types.new_from_dict({
+    'pretix.team.member.added': _('{user} has been added to the team.'),
+    'pretix.team.member.removed': _('{user} has been removed from the team.'),
+    'pretix.team.invite.created': _('{user} has been invited to the team.'),
+    'pretix.team.invite.resent': _('Invite for {user} has been resent.'),
+})
+class CoreTeamMembershipLogEntryType(TeamMembershipLogEntryType):
+    pass
+
+
+@log_entry_types.new()
+class TeamMemberJoinedLogEntryType(LogEntryType):
+    action_type = 'pretix.team.member.joined'
+
+    def display(self, logentry):
+        return _('{user} has joined the team using the invite sent to {email}.').format(
+            user=logentry.parsed_data.get('email'), email=logentry.parsed_data.get('invite_email')
+        )
+
+
+@log_entry_types.new()
+class UserSettingsChangedLogEntryType(LogEntryType):
+    action_type = 'pretix.user.settings.changed'
+
+    def display(self, logentry):
+        text = str(_('Your account settings have been changed.'))
+        if 'email' in logentry.parsed_data:
+            text = text + ' ' + str(
+                _('Your email address has been changed to {email}.').format(email=logentry.parsed_data['email']))
+        if 'new_pw' in logentry.parsed_data:
+            text = text + ' ' + str(_('Your password has been changed.'))
+        if logentry.parsed_data.get('is_active') is True:
+            text = text + ' ' + str(_('Your account has been enabled.'))
+        elif logentry.parsed_data.get('is_active') is False:
+            text = text + ' ' + str(_('Your account has been disabled.'))
+        return text
+
+
+class UserImpersonatedLogEntryType(LogEntryType):
+    def display(self, logentry):
+        return self.plain.format(logentry.parsed_data['other_email'])
+
+
+@log_entry_types.new_from_dict({
+    'pretix.control.auth.user.impersonated': _('You impersonated {}.'),
+    'pretix.control.auth.user.impersonate_stopped': _('You stopped impersonating {}.'),
+})
+class CoreUserImpersonatedLogEntryType(UserImpersonatedLogEntryType):
+    pass
+
+
+@log_entry_types.new_from_dict({
+    'pretix.object.cloned': _('This object has been created by cloning.'),
+    'pretix.organizer.changed': _('The organizer has been changed.'),
+    'pretix.organizer.settings': _('The organizer settings have been changed.'),
+    'pretix.organizer.footerlinks.changed': _('The footer links have been changed.'),
+    'pretix.organizer.export.schedule.added': _('A scheduled export has been added.'),
+    'pretix.organizer.export.schedule.changed': _('A scheduled export has been changed.'),
+    'pretix.organizer.export.schedule.deleted': _('A scheduled export has been deleted.'),
+    'pretix.organizer.export.schedule.executed': _('A scheduled export has been executed.'),
+    'pretix.organizer.export.schedule.failed': _('A scheduled export has failed: {reason}.'),
+    'pretix.giftcards.acceptance.added': _('Gift card acceptance for another organizer has been added.'),
+    'pretix.giftcards.acceptance.removed': _('Gift card acceptance for another organizer has been removed.'),
+    'pretix.giftcards.acceptance.acceptor.invited': _('A new gift card acceptor has been invited.'),
+    'pretix.giftcards.acceptance.acceptor.removed': _('A gift card acceptor has been removed.'),
+    'pretix.giftcards.acceptance.issuer.removed': _('A gift card issuer has been removed or declined.'),
+    'pretix.giftcards.acceptance.issuer.accepted': _('A new gift card issuer has been accepted.'),
+    'pretix.webhook.created': _('The webhook has been created.'),
+    'pretix.webhook.changed': _('The webhook has been changed.'),
+    'pretix.webhook.retries.expedited': _('The webhook call retry jobs have been manually expedited.'),
+    'pretix.webhook.retries.dropped': _('The webhook call retry jobs have been dropped.'),
+    'pretix.ssoprovider.created': _('The SSO provider has been created.'),
+    'pretix.ssoprovider.changed': _('The SSO provider has been changed.'),
+    'pretix.ssoprovider.deleted': _('The SSO provider has been deleted.'),
+    'pretix.ssoclient.created': _('The SSO client has been created.'),
+    'pretix.ssoclient.changed': _('The SSO client has been changed.'),
+    'pretix.ssoclient.deleted': _('The SSO client has been deleted.'),
+    'pretix.membershiptype.created': _('The membership type has been created.'),
+    'pretix.membershiptype.changed': _('The membership type has been changed.'),
+    'pretix.membershiptype.deleted': _('The membership type has been deleted.'),
+    'pretix.saleschannel.created': _('The sales channel has been created.'),
+    'pretix.saleschannel.changed': _('The sales channel has been changed.'),
+    'pretix.saleschannel.deleted': _('The sales channel has been deleted.'),
+    'pretix.customer.created': _('The account has been created.'),
+    'pretix.customer.changed': _('The account has been changed.'),
+    'pretix.customer.membership.created': _('A membership for this account has been added.'),
+    'pretix.customer.membership.changed': _('A membership of this account has been changed.'),
+    'pretix.customer.membership.deleted': _('A membership of this account has been deleted.'),
+    'pretix.customer.anonymized': _('The account has been disabled and anonymized.'),
+    'pretix.customer.password.resetrequested': _('A new password has been requested.'),
+    'pretix.customer.password.set': _('A new password has been set.'),
+    'pretix.reusable_medium.created': _('The reusable medium has been created.'),
+    'pretix.reusable_medium.created.auto': _('The reusable medium has been created automatically.'),
+    'pretix.reusable_medium.changed': _('The reusable medium has been changed.'),
+    'pretix.reusable_medium.linked_orderposition.changed': _('The medium has been connected to a new ticket.'),
+    'pretix.reusable_medium.linked_giftcard.changed': _('The medium has been connected to a new gift card.'),
+    'pretix.email.error': _('Sending of an email has failed.'),
+    'pretix.event.comment': _('The event\'s internal comment has been updated.'),
+    'pretix.event.canceled': _('The event has been canceled.'),
+    'pretix.event.deleted': _('An event has been deleted.'),
+    'pretix.event.shredder.started': _('A removal process for personal data has been started.'),
+    'pretix.event.shredder.completed': _('A removal process for personal data has been completed.'),
+    'pretix.event.export.schedule.added': _('A scheduled export has been added.'),
+    'pretix.event.export.schedule.changed': _('A scheduled export has been changed.'),
+    'pretix.event.export.schedule.deleted': _('A scheduled export has been deleted.'),
+    'pretix.event.export.schedule.executed': _('A scheduled export has been executed.'),
+    'pretix.event.export.schedule.failed': _('A scheduled export has failed: {reason}.'),
+    'pretix.control.auth.user.created': _('The user has been created.'),
+    'pretix.control.auth.user.new_source': _('A first login using {agent_type} on {os_type} from {country} has '
+                                             'been detected.'),
+    'pretix.user.settings.2fa.enabled': _('Two-factor authentication has been enabled.'),
+    'pretix.user.settings.2fa.disabled': _('Two-factor authentication has been disabled.'),
+    'pretix.user.settings.2fa.regenemergency': _('Your two-factor emergency codes have been regenerated.'),
+    'pretix.user.settings.2fa.emergency': _('A two-factor emergency code has been generated.'),
+    'pretix.user.settings.2fa.device.added': _('A new two-factor authentication device "{name}" has been added to '
+                                               'your account.'),
+    'pretix.user.settings.2fa.device.deleted': _('The two-factor authentication device "{name}" has been removed '
+                                                 'from your account.'),
+    'pretix.user.settings.notifications.enabled': _('Notifications have been enabled.'),
+    'pretix.user.settings.notifications.disabled': _('Notifications have been disabled.'),
+    'pretix.user.settings.notifications.changed': _('Your notification settings have been changed.'),
+    'pretix.user.anonymized': _('This user has been anonymized.'),
+    'pretix.user.oauth.authorized': _('The application "{application_name}" has been authorized to access your '
+                                      'account.'),
+    'pretix.control.auth.user.forgot_password.mail_sent': _('Password reset mail sent.'),
+    'pretix.control.auth.user.forgot_password.recovered': _('The password has been reset.'),
+    'pretix.control.auth.user.forgot_password.denied.repeated': _('A repeated password reset has been denied, as '
+                                                                  'the last request was less than 24 hours ago.'),
+    'pretix.organizer.deleted': _('The organizer "{name}" has been deleted.'),
+    'pretix.waitinglist.voucher': _('A voucher has been sent to a person on the waiting list.'),  # legacy
+    'pretix.event.orders.waitinglist.voucher_assigned': _('A voucher has been sent to a person on the waiting list.'),
+    'pretix.event.orders.waitinglist.deleted': _('An entry has been removed from the waiting list.'),
+    'pretix.event.order.waitinglist.transferred': _('An entry has been transferred to another waiting list.'),  # legacy
+    'pretix.event.orders.waitinglist.changed': _('An entry has been changed on the waiting list.'),
+    'pretix.event.orders.waitinglist.added': _('An entry has been added to the waiting list.'),
+    'pretix.team.created': _('The team has been created.'),
+    'pretix.team.changed': _('The team settings have been changed.'),
+    'pretix.team.deleted': _('The team has been deleted.'),
+    'pretix.gate.created': _('The gate has been created.'),
+    'pretix.gate.changed': _('The gate has been changed.'),
+    'pretix.gate.deleted': _('The gate has been deleted.'),
+    'pretix.subevent.deleted': pgettext_lazy('subevent', 'The event date has been deleted.'),
+    'pretix.subevent.canceled': pgettext_lazy('subevent', 'The event date has been canceled.'),
+    'pretix.subevent.changed': pgettext_lazy('subevent', 'The event date has been changed.'),
+    'pretix.subevent.added': pgettext_lazy('subevent', 'The event date has been created.'),
+    'pretix.subevent.quota.added': pgettext_lazy('subevent', 'A quota has been added to the event date.'),
+    'pretix.subevent.quota.changed': pgettext_lazy('subevent', 'A quota has been changed on the event date.'),
+    'pretix.subevent.quota.deleted': pgettext_lazy('subevent', 'A quota has been removed from the event date.'),
+    'pretix.device.created': _('The device has been created.'),
+    'pretix.device.changed': _('The device has been changed.'),
+    'pretix.device.revoked': _('Access of the device has been revoked.'),
+    'pretix.device.initialized': _('The device has been initialized.'),
+    'pretix.device.keyroll': _('The access token of the device has been regenerated.'),
+    'pretix.device.updated': _('The device has notified the server of an hardware or software update.'),
+    'pretix.giftcards.created': _('The gift card has been created.'),
+    'pretix.giftcards.modified': _('The gift card has been changed.'),
+    'pretix.giftcards.transaction.manual': _('A manual transaction has been performed.'),
+    'pretix.team.token.created': _('The token "{name}" has been created.'),
+    'pretix.team.token.deleted': _('The token "{name}" has been revoked.'),
+})
+class CoreLogEntryType(LogEntryType):
+    pass
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.item_meta_property.added': _('A meta property has been added to this event.'),
+    'pretix.event.item_meta_property.deleted': _('A meta property has been removed from this event.'),
+    'pretix.event.item_meta_property.changed': _('A meta property has been changed on this event.'),
+    'pretix.event.checkinlist.added': _('The check-in list has been added.'),
+    'pretix.event.checkinlist.deleted': _('The check-in list has been deleted.'),
+    'pretix.event.checkinlists.deleted': _('The check-in list has been deleted.'),  # backwards compatibility
+    'pretix.event.checkinlist.changed': _('The check-in list has been changed.'),
+    'pretix.event.settings': _('The event settings have been changed.'),
+    'pretix.event.tickets.settings': _('The ticket download settings have been changed.'),
+    'pretix.event.live.activated': _('The shop has been taken live.'),
+    'pretix.event.live.deactivated': _('The shop has been taken offline.'),
+    'pretix.event.testmode.activated': _('The shop has been taken into test mode.'),
+    'pretix.event.testmode.deactivated': _('The test mode has been disabled.'),
+    'pretix.event.added': _('The event has been created.'),
+    'pretix.event.changed': _('The event details have been changed.'),
+    'pretix.event.footerlinks.changed': _('The footer links have been changed.'),
+    'pretix.event.question.option.added': _('An answer option has been added to the question.'),
+    'pretix.event.question.option.deleted': _('An answer option has been removed from the question.'),
+    'pretix.event.question.option.changed': _('An answer option has been changed.'),
+    'pretix.event.permissions.added': _('A user has been added to the event team.'),
+    'pretix.event.permissions.invited': _('A user has been invited to the event team.'),
+    'pretix.event.permissions.changed': _('A user\'s permissions have been changed.'),
+    'pretix.event.permissions.deleted': _('A user has been removed from the event team.'),
+})
+class CoreEventLogEntryType(EventLogEntryType):
+    pass
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.plugins.enabled': _('The plugin has been enabled.'),
+    'pretix.event.plugins.disabled': _('The plugin has been disabled.'),
+})
+class EventPluginStateLogEntryType(EventLogEntryType):
+    object_link_wrapper = _('Plugin {val}')
+
+    def get_object_link_info(self, logentry) -> dict:
+        if 'plugin' in logentry.parsed_data:
+            app = app_cache.get(logentry.parsed_data['plugin'])
+            if app and hasattr(app, 'PretixPluginMeta'):
+                return {
+                    'href': reverse('control:event.settings.plugins', kwargs={
+                        'organizer': logentry.event.organizer.slug,
+                        'event': logentry.event.slug,
+                    }) + '#plugin_' + logentry.parsed_data['plugin'],
+                    'val': app.PretixPluginMeta.name
+                }
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.item.added': _('The product has been created.'),
+    'pretix.event.item.changed': _('The product has been changed.'),
+    'pretix.event.item.reordered': _('The product has been reordered.'),
+    'pretix.event.item.deleted': _('The product has been deleted.'),
+    'pretix.event.item.addons.added': _('An add-on has been added to this product.'),
+    'pretix.event.item.addons.removed': _('An add-on has been removed from this product.'),
+    'pretix.event.item.addons.changed': _('An add-on has been changed on this product.'),
+    'pretix.event.item.bundles.added': _('A bundled item has been added to this product.'),
+    'pretix.event.item.bundles.removed': _('A bundled item has been removed from this product.'),
+    'pretix.event.item.bundles.changed': _('A bundled item has been changed on this product.'),
+})
+class CoreItemLogEntryType(ItemLogEntryType):
+    pass
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.item.variation.added': _('The variation "{value}" has been created.'),
+    'pretix.event.item.variation.deleted': _('The variation "{value}" has been deleted.'),
+    'pretix.event.item.variation.changed': _('The variation "{value}" has been changed.'),
+})
+class VariationLogEntryType(ItemLogEntryType):
+    def display(self, logentry):
+        if 'value' not in logentry.parsed_data:
+            # Backwards compatibility
+            var = ItemVariation.objects.filter(id=logentry.parsed_data['id']).first()
+            if var:
+                logentry.parsed_data['value'] = str(var.value)
+            else:
+                logentry.parsed_data['value'] = '?'
+        else:
+            logentry.parsed_data['value'] = LazyI18nString(logentry.parsed_data['value'])
+        return super().display(logentry)
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.order.payment.confirmed': _('Payment {local_id} has been confirmed.'),
+    'pretix.event.order.payment.canceled': _('Payment {local_id} has been canceled.'),
+    'pretix.event.order.payment.canceled.failed': _('Canceling payment {local_id} has failed.'),
+    'pretix.event.order.payment.started': _('Payment {local_id} has been started.'),
+    'pretix.event.order.payment.failed': _('Payment {local_id} has failed.'),
+    'pretix.event.order.quotaexceeded': _('The order could not be marked as paid: {message}'),
+    'pretix.event.order.overpaid': _('The order has been overpaid.'),
+    'pretix.event.order.refund.created': _('Refund {local_id} has been created.'),
+    'pretix.event.order.refund.created.externally': _('Refund {local_id} has been created by an external entity.'),
+    'pretix.event.order.refund.requested': _('The customer requested you to issue a refund.'),
+    'pretix.event.order.refund.done': _('Refund {local_id} has been completed.'),
+    'pretix.event.order.refund.canceled': _('Refund {local_id} has been canceled.'),
+    'pretix.event.order.refund.failed': _('Refund {local_id} has failed.'),
+})
+class CoreOrderPaymentLogEntryType(OrderLogEntryType):
+    pass
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.quota.added': _('The quota has been added.'),
+    'pretix.event.quota.deleted': _('The quota has been deleted.'),
+    'pretix.event.quota.changed': _('The quota has been changed.'),
+    'pretix.event.quota.closed': _('The quota has closed.'),
+    'pretix.event.quota.opened': _('The quota has been re-opened.'),
+})
+class CoreQuotaLogEntryType(QuotaLogEntryType):
+    pass
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.question.added': _('The question has been added.'),
+    'pretix.event.question.deleted': _('The question has been deleted.'),
+    'pretix.event.question.changed': _('The question has been changed.'),
+    'pretix.event.question.reordered': _('The question has been reordered.'),
+})
+class CoreQuestionLogEntryType(QuestionLogEntryType):
+    pass
+
+
+@log_entry_types.new_from_dict({
+    'pretix.event.discount.added': _('The discount has been added.'),
+    'pretix.event.discount.deleted': _('The discount has been deleted.'),
+    'pretix.event.discount.changed': _('The discount has been changed.'),
+})
+class CoreDiscountLogEntryType(DiscountLogEntryType):
+    pass
+
+
+@log_entry_types.new()
+class LegacyCheckinLogEntryType(OrderLogEntryType):
+    action_type = 'pretix.control.views.checkin'
+
+    def display(self, logentry):
+        # deprecated
+        dt = dateutil.parser.parse(logentry.parsed_data.get('datetime'))
+        tz = logentry.event.timezone
+        dt_formatted = date_format(dt.astimezone(tz), "SHORT_DATETIME_FORMAT")
+        if 'list' in logentry.parsed_data:
+            try:
+                checkin_list = logentry.event.checkin_lists.get(pk=logentry.parsed_data.get('list')).name
+            except CheckinList.DoesNotExist:
+                checkin_list = _("(unknown)")
+        else:
+            checkin_list = _("(unknown)")
+
+        if logentry.parsed_data.get('first'):
+            return _('Position #{posid} has been checked in manually at {datetime} on list "{list}".').format(
+                posid=logentry.parsed_data.get('positionid'),
+                datetime=dt_formatted,
+                list=checkin_list,
+            )
+        return _('Position #{posid} has been checked in again at {datetime} on list "{list}".').format(
+            posid=logentry.parsed_data.get('positionid'),
+            datetime=dt_formatted,
+            list=checkin_list
+        )

src/pretix/control/templates/pretixcontrol/event/plugins.html

@@ -23,7 +23,7 @@
                     <legend>{{ catlabel }}</legend>
                     <div class="plugin-list">
                         {% for plugin in plist %}
-                            <div class="plugin-container {% if plugin.featured %}featured-plugin{% endif %}">
+                            <div class="plugin-container {% if plugin.featured %}featured-plugin{% endif %}" id="plugin_{{ plugin.module }}">
                             {% if plugin.featured %}
                                <div class="panel panel-default">
                                     <div class="panel-body">

src/pretix/plugins/badges/signals.py

@@ -26,13 +26,12 @@ from collections import defaultdict
 from django.dispatch import receiver
 from django.template.loader import get_template
 from django.urls import resolve, reverse
-from django.utils.html import escape
 from django.utils.translation import gettext_lazy as _
 
+from pretix.base.logentrytypes import EventLogEntryType, log_entry_types
 from pretix.base.models import Event, Order
 from pretix.base.signals import (
-    event_copy_data, item_copy_data, logentry_display, logentry_object_link,
-    register_data_exporters,
+    event_copy_data, item_copy_data, register_data_exporters,
 )
 from pretix.control.signals import (
     item_forms, nav_event, order_info, order_position_buttons,
@@ -173,35 +172,13 @@ def control_order_info(sender: Event, request, order: Order, **kwargs):
     return template.render(ctx, request=request)
 
 
-@receiver(signal=logentry_display, dispatch_uid="badges_logentry_display")
-def badges_logentry_display(sender, logentry, **kwargs):
-    if not logentry.action_type.startswith('pretix.plugins.badges'):
-        return
-
-    plains = {
-        'pretix.plugins.badges.layout.added': _('Badge layout created.'),
-        'pretix.plugins.badges.layout.deleted': _('Badge layout deleted.'),
-        'pretix.plugins.badges.layout.changed': _('Badge layout changed.'),
-    }
-
-    if logentry.action_type in plains:
-        return plains[logentry.action_type]
-
-
-@receiver(signal=logentry_object_link, dispatch_uid="badges_logentry_object_link")
-def badges_logentry_object_link(sender, logentry, **kwargs):
-    if not logentry.action_type.startswith('pretix.plugins.badges.layout') or not isinstance(logentry.content_object,
-                                                                                             BadgeLayout):
-        return
-
-    a_text = _('Badge layout {val}')
-    a_map = {
-        'href': reverse('plugins:badges:edit', kwargs={
-            'event': sender.slug,
-            'organizer': sender.organizer.slug,
-            'layout': logentry.content_object.id
-        }),
-        'val': escape(logentry.content_object.name),
-    }
-    a_map['val'] = '<a href="{href}">{val}</a>'.format_map(a_map)
-    return a_text.format_map(a_map)
+@log_entry_types.new_from_dict({
+    'pretix.plugins.badges.layout.added': _('Badge layout created.'),
+    'pretix.plugins.badges.layout.deleted': _('Badge layout deleted.'),
+    'pretix.plugins.badges.layout.changed': _('Badge layout changed.'),
+})
+class BadgeLogEntryType(EventLogEntryType):
+    object_type = BadgeLayout
+    object_link_wrapper = _('Badge layout {val}')
+    object_link_viewname = 'plugins:badges:edit'
+    object_link_argname = 'layout'

src/pretix/plugins/banktransfer/signals.py

@@ -25,9 +25,12 @@ from django.urls import resolve, reverse
 from django.utils.translation import gettext_lazy as _, gettext_noop
 from i18nfield.strings import LazyI18nString
 
-from pretix.base.signals import logentry_display, register_payment_providers
+from pretix.base.signals import register_payment_providers
 from pretix.control.signals import html_head, nav_event, nav_organizer
 
+from ...base.logentrytypes import (
+    ClearDataShredderMixin, OrderLogEntryType, log_entry_types,
+)
 from ...base.settings import settings_hierarkey
 from .payment import BankTransfer
 
@@ -117,13 +120,10 @@ def html_head_presale(sender, request=None, **kwargs):
         return ""
 
 
-@receiver(signal=logentry_display)
-def pretixcontrol_logentry_display(sender, logentry, **kwargs):
-    plains = {
-        'pretix.plugins.banktransfer.order.email.invoice': _('The invoice was sent to the designated email address.'),
-    }
-    if logentry.action_type in plains:
-        return plains[logentry.action_type]
+@log_entry_types.new()
+class BanktransferOrderEmailInvoiceLogEntryType(OrderLogEntryType, ClearDataShredderMixin):
+    action_type = 'pretix.plugins.banktransfer.order.email.invoice'
+    plain = _('The invoice was sent to the designated email address.')
 
 
 settings_hierarkey.add_default(

src/pretix/plugins/paypal/signals.py

@@ -22,17 +22,10 @@
 
 from django.dispatch import receiver
 
-from pretix.base.signals import logentry_display, register_payment_providers
+from pretix.base.signals import register_payment_providers
 
 
 @receiver(register_payment_providers, dispatch_uid="payment_paypal")
 def register_payment_provider(sender, **kwargs):
     from .payment import Paypal
     return Paypal
-
-
-@receiver(signal=logentry_display, dispatch_uid="paypal_logentry_display")
-def pretixcontrol_logentry_display(sender, logentry, **kwargs):
-    from pretix.plugins.paypal2.signals import pretixcontrol_logentry_display
-
-    return pretixcontrol_logentry_display(sender, logentry, **kwargs)

src/pretix/plugins/paypal2/signals.py

@@ -19,7 +19,6 @@
 # You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
 # <https://www.gnu.org/licenses/>.
 #
-import json
 from collections import OrderedDict
 
 from django import forms
@@ -32,10 +31,11 @@ from django.utils.crypto import get_random_string
 from django.utils.translation import gettext_lazy as _, pgettext_lazy
 
 from pretix.base.forms import SecretKeySettingsField
+from pretix.base.logentrytypes import EventLogEntryType, log_entry_types
 from pretix.base.middleware import _merge_csp, _parse_csp, _render_csp
 from pretix.base.settings import settings_hierarkey
 from pretix.base.signals import (
-    logentry_display, register_global_settings, register_payment_providers,
+    register_global_settings, register_payment_providers,
 )
 from pretix.plugins.paypal2.payment import PaypalMethod
 from pretix.presale.signals import html_head, process_response
@@ -47,33 +47,32 @@ def register_payment_provider(sender, **kwargs):
     return [PaypalSettingsHolder, PaypalWallet, PaypalAPM]
 
 
-@receiver(signal=logentry_display, dispatch_uid="paypal2_logentry_display")
-def pretixcontrol_logentry_display(sender, logentry, **kwargs):
-    if logentry.action_type != 'pretix.plugins.paypal.event':
-        return
+@log_entry_types.new()
+class PaypalEventLogEntryType(EventLogEntryType):
+    action_type = 'pretix.plugins.paypal.event'
 
-    data = json.loads(logentry.data)
-    event_type = data.get('event_type')
-    text = None
-    plains = {
-        'PAYMENT.SALE.COMPLETED': _('Payment completed.'),
-        'PAYMENT.SALE.DENIED': _('Payment denied.'),
-        'PAYMENT.SALE.REFUNDED': _('Payment refunded.'),
-        'PAYMENT.SALE.REVERSED': _('Payment reversed.'),
-        'PAYMENT.SALE.PENDING': _('Payment pending.'),
-        'CHECKOUT.ORDER.APPROVED': pgettext_lazy('paypal', 'Order approved.'),
-        'CHECKOUT.ORDER.COMPLETED': pgettext_lazy('paypal', 'Order completed.'),
-        'PAYMENT.CAPTURE.COMPLETED': pgettext_lazy('paypal', 'Capture completed.'),
-        'PAYMENT.CAPTURE.PENDING': pgettext_lazy('paypal', 'Capture pending.'),
-    }
+    def display(self, logentry):
+        event_type = logentry.parsed_data.get('event_type')
+        text = None
+        plains = {
+            'PAYMENT.SALE.COMPLETED': _('Payment completed.'),
+            'PAYMENT.SALE.DENIED': _('Payment denied.'),
+            'PAYMENT.SALE.REFUNDED': _('Payment refunded.'),
+            'PAYMENT.SALE.REVERSED': _('Payment reversed.'),
+            'PAYMENT.SALE.PENDING': _('Payment pending.'),
+            'CHECKOUT.ORDER.APPROVED': pgettext_lazy('paypal', 'Order approved.'),
+            'CHECKOUT.ORDER.COMPLETED': pgettext_lazy('paypal', 'Order completed.'),
+            'PAYMENT.CAPTURE.COMPLETED': pgettext_lazy('paypal', 'Capture completed.'),
+            'PAYMENT.CAPTURE.PENDING': pgettext_lazy('paypal', 'Capture pending.'),
+        }
 
-    if event_type in plains:
-        text = plains[event_type]
-    else:
-        text = event_type
+        if event_type in plains:
+            text = plains[event_type]
+        else:
+            text = event_type
 
-    if text:
-        return _('PayPal reported an event: {}').format(text)
+        if text:
+            return _('PayPal reported an event: {}').format(text)
 
 
 @receiver(register_global_settings, dispatch_uid='paypal2_global_settings')

src/pretix/plugins/sendmail/signals.py

@@ -46,13 +46,16 @@ from django.utils.timezone import now
 from django.utils.translation import gettext_lazy as _
 from django_scopes import scope, scopes_disabled
 
+from pretix.base.logentrytypes import (
+    EventLogEntryType, OrderLogEntryType, log_entry_types,
+)
 from pretix.base.models import SubEvent
 from pretix.base.signals import (
-    EventPluginSignal, event_copy_data, logentry_display, periodic_task,
+    EventPluginSignal, event_copy_data, periodic_task,
 )
 from pretix.control.signals import nav_event
 from pretix.helpers import OF_SELF
-from pretix.plugins.sendmail.models import ScheduledMail
+from pretix.plugins.sendmail.models import Rule, ScheduledMail
 from pretix.plugins.sendmail.views import OrderSendView, WaitinglistSendView
 
 logger = logging.getLogger(__name__)
@@ -115,21 +118,28 @@ def control_nav_import(sender, request=None, **kwargs):
     ]
 
 
-@receiver(signal=logentry_display)
-def pretixcontrol_logentry_display(sender, logentry, **kwargs):
-    plains = {
-        'pretix.plugins.sendmail.sent': _('Mass email was sent to customers or attendees.'),
-        'pretix.plugins.sendmail.sent.waitinglist': _('Mass email was sent to waiting list entries.'),
-        'pretix.plugins.sendmail.order.email.sent': _('The order received a mass email.'),
-        'pretix.plugins.sendmail.order.email.sent.attendee': _('A ticket holder of this order received a mass email.'),
-        'pretix.plugins.sendmail.rule.added': _('An email rule was created'),
-        'pretix.plugins.sendmail.rule.changed': _('An email rule was updated'),
-        'pretix.plugins.sendmail.rule.order.email.sent': _('A scheduled email was sent to the order'),
-        'pretix.plugins.sendmail.rule.order.position.email.sent': _('A scheduled email was sent to a ticket holder'),
-        'pretix.plugins.sendmail.rule.deleted': _('An email rule was deleted'),
-    }
-    if logentry.action_type in plains:
-        return plains[logentry.action_type]
+@log_entry_types.new('pretix.plugins.sendmail.sent', _('Mass email was sent to customers or attendees.'))
+@log_entry_types.new('pretix.plugins.sendmail.sent.waitinglist', _('Mass email was sent to waiting list entries.'))
+class SendmailPluginLogEntryType(EventLogEntryType):
+    pass
+
+
+@log_entry_types.new('pretix.plugins.sendmail.order.email.sent', _('The order received a mass email.'))
+@log_entry_types.new('pretix.plugins.sendmail.order.email.sent.attendee', _('A ticket holder of this order received a mass email.'))
+class SendmailPluginOrderLogEntryType(OrderLogEntryType):
+    pass
+
+
+@log_entry_types.new('pretix.plugins.sendmail.rule.added', _('An email rule was created'))
+@log_entry_types.new('pretix.plugins.sendmail.rule.changed', _('An email rule was updated'))
+@log_entry_types.new('pretix.plugins.sendmail.rule.order.email.sent', _('A scheduled email was sent to the order'))
+@log_entry_types.new('pretix.plugins.sendmail.rule.order.position.email.sent', _('A scheduled email was sent to a ticket holder'))
+@log_entry_types.new('pretix.plugins.sendmail.rule.deleted', _('An email rule was deleted'))
+class SendmailPluginRuleLogEntryType(EventLogEntryType):
+    object_type = Rule
+    object_link_wrapper = _('Mail rule {val}')
+    object_link_viewname = 'plugins:sendmail:rule.update'
+    object_link_argname = 'rule'
 
 
 @receiver(periodic_task)

src/pretix/plugins/ticketoutputpdf/signals.py

@@ -24,10 +24,9 @@ import json
 
 from django.dispatch import receiver
 from django.template.loader import get_template
-from django.urls import reverse
-from django.utils.html import escape
 from django.utils.translation import gettext_lazy as _
 
+from pretix.base.logentrytypes import EventLogEntryType, log_entry_types
 from pretix.base.models import Event, SalesChannel
 from pretix.base.signals import (  # NOQA: legacy import
     EventPluginSignal, event_copy_data, item_copy_data, layout_text_variables,
@@ -134,38 +133,16 @@ def pdf_event_copy_data_receiver(sender, other, item_map, question_map, **kwargs
     return layout_map
 
 
-@receiver(signal=logentry_display, dispatch_uid="pretix_ticketoutputpdf_logentry_display")
-def pdf_logentry_display(sender, logentry, **kwargs):
-    if not logentry.action_type.startswith('pretix.plugins.ticketoutputpdf'):
-        return
-
-    plains = {
-        'pretix.plugins.ticketoutputpdf.layout.added': _('Ticket layout created.'),
-        'pretix.plugins.ticketoutputpdf.layout.deleted': _('Ticket layout deleted.'),
-        'pretix.plugins.ticketoutputpdf.layout.changed': _('Ticket layout changed.'),
-    }
-
-    if logentry.action_type in plains:
-        return plains[logentry.action_type]
-
-
-@receiver(signal=logentry_object_link, dispatch_uid="pretix_ticketoutputpdf_logentry_object_link")
-def pdf_logentry_object_link(sender, logentry, **kwargs):
-    if not logentry.action_type.startswith('pretix.plugins.ticketoutputpdf.layout') or not isinstance(
-            logentry.content_object, TicketLayout):
-        return
-
-    a_text = _('Ticket layout {val}')
-    a_map = {
-        'href': reverse('plugins:ticketoutputpdf:edit', kwargs={
-            'event': sender.slug,
-            'organizer': sender.organizer.slug,
-            'layout': logentry.content_object.id
-        }),
-        'val': escape(logentry.content_object.name),
-    }
-    a_map['val'] = '<a href="{href}">{val}</a>'.format_map(a_map)
-    return a_text.format_map(a_map)
+@log_entry_types.new_from_dict({
+    'pretix.plugins.ticketoutputpdf.layout.added': _('Ticket layout created.'),
+    'pretix.plugins.ticketoutputpdf.layout.deleted': _('Ticket layout deleted.'),
+    'pretix.plugins.ticketoutputpdf.layout.changed': _('Ticket layout changed.'),
+})
+class PdfTicketLayoutLogEntryType(EventLogEntryType):
+    object_type = TicketLayout
+    object_link_wrapper = _('Ticket layout {val}')
+    object_link_viewname = 'plugins:ticketoutputpdf:edit'
+    object_link_argname = 'layout'
 
 
 def _ticket_layouts_for_item(request, item):

src/pretix/settings.py

@@ -435,14 +435,6 @@ REST_FRAMEWORK = {
 }
 
 
-CORE_MODULES = {
-    "pretix.base",
-    "pretix.presale",
-    "pretix.control",
-    "pretix.plugins.checkinlists",
-    "pretix.plugins.reports",
-}
-
 MIDDLEWARE = [
     'pretix.helpers.logs.RequestIdMiddleware',
     'pretix.api.middleware.IdempotencyMiddleware',

src/tests/base/test_registry.py

@@ -0,0 +1,179 @@
+#
+# This file is part of pretix (Community Edition).
+#
+# Copyright (C) 2014-2020 Raphael Michel and contributors
+# Copyright (C) 2020-2021 rami.io GmbH and contributors
+#
+# This program is free software: you can redistribute it and/or modify it under the terms of the GNU Affero General
+# Public License as published by the Free Software Foundation in version 3 of the License.
+#
+# ADDITIONAL TERMS APPLY: Pursuant to Section 7 of the GNU Affero General Public License, additional terms are
+# applicable granting you additional permissions and placing additional restrictions on your usage of this software.
+# Please refer to the pretix LICENSE file to obtain the full terms applicable to this work. If you did not receive
+# this file, see <https://pretix.eu/about/en/license>.
+#
+# This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+# warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Affero General Public License for more
+# details.
+#
+# You should have received a copy of the GNU Affero General Public License along with this program.  If not, see
+# <https://www.gnu.org/licenses/>.
+#
+from unittest import mock
+
+import pytest
+
+from pretix.base.logentrytypes import (
+    ItemLogEntryType, LogEntryType, LogEntryTypeRegistry,
+)
+from pretix.base.signals import Registry
+
+
+def test_registry_classes():
+    animal_type_registry = Registry({"type": lambda s: s.__name__, "classis": lambda s: s.classis})
+
+    @animal_type_registry.register
+    class Cat:
+        classis = 'mammalia'
+
+        def make_sound(self):
+            return "meow"
+
+    @animal_type_registry.register
+    class Dog:
+        classis = 'mammalia'
+
+        def make_sound(self):
+            return "woof"
+
+    @animal_type_registry.register
+    class Cricket:
+        classis = 'insecta'
+
+        def make_sound(self):
+            return "chirp"
+
+    # test retrieving and instantiating a class based on metadata value
+    clz, meta = animal_type_registry.get(type="Cat")
+    assert clz().make_sound() == "meow"
+    assert meta.get('type') == "Cat"
+
+    clz, meta = animal_type_registry.get(type="Dog")
+    assert clz().make_sound() == "woof"
+    assert meta.get('type') == "Dog"
+
+    # check that None is returned when no class exists with the specified metadata value
+    clz, meta = animal_type_registry.get(type="Unicorn")
+    assert clz is None
+    assert meta is None
+
+    # check that an error is raised when trying to retrieve by an undefined metadata key
+    with pytest.raises(Exception):
+        _, _ = animal_type_registry.get(whatever="hello")
+
+    # test finding all entries with a given metadata value
+    mammals = animal_type_registry.filter(classis='mammalia')
+    assert set(cls for cls, meta in mammals) == {Cat, Dog}
+    assert all(meta['classis'] == 'mammalia' for cls, meta in mammals)
+
+    insects = animal_type_registry.filter(classis='insecta')
+    assert set(cls for cls, meta in insects) == {Cricket}
+
+    fantasy = animal_type_registry.filter(classis='fantasia')
+    assert set(cls for cls, meta in fantasy) == set()
+
+    # check normal object instantiation still works with our decorator
+    assert Cat().make_sound() == "meow"
+
+
+def test_registry_instances():
+    animal_sound_registry = Registry({"animal": lambda s: s.animal})
+
+    @animal_sound_registry.new("dog", "woof")
+    @animal_sound_registry.new("cricket", "chirp")
+    class AnimalSound:
+        def __init__(self, animal, sound):
+            self.animal = animal
+            self.sound = sound
+
+        def make_sound(self):
+            return self.sound
+
+    @animal_sound_registry.new()
+    class CatSound(AnimalSound):
+        def __init__(self):
+            super().__init__(animal="cat", sound=["meow", "meww", "miaou"])
+            self.i = 0
+
+        def make_sound(self):
+            self.i += 1
+            return self.sound[self.i % len(self.sound)]
+
+    # test registry
+    assert animal_sound_registry.get(animal='dog')[0].make_sound() == "woof"
+    assert animal_sound_registry.get(animal='dog')[0].make_sound() == "woof"
+    assert animal_sound_registry.get(animal='cricket')[0].make_sound() == "chirp"
+    assert animal_sound_registry.get(animal='cat')[0].make_sound() == "meww"
+    assert animal_sound_registry.get(animal='cat')[0].make_sound() == "miaou"
+    assert animal_sound_registry.get(animal='cat')[0].make_sound() == "meow"
+
+    # check normal object instantiation still works with our decorator
+    assert AnimalSound("test", "test").make_sound() == "test"
+
+
+def test_registry_prevent_duplicates():
+    my_registry = Registry({"animal": lambda s: s.animal})
+
+    class AnimalSound:
+        def __init__(self, animal, sound):
+            self.animal = animal
+            self.sound = sound
+
+    cat = AnimalSound("cat", "meow")
+    my_registry.register(cat)
+
+    with pytest.raises(RuntimeError):
+        my_registry.register(cat)
+
+
+def test_logentrytype_registry():
+    reg = LogEntryTypeRegistry()
+
+    with mock.patch('pretix.base.signals.get_defining_app') as mock_get_defining_app:
+        mock_get_defining_app.return_value = 'my_plugin'
+
+        @reg.new("foo.mytype")
+        class MyType(LogEntryType):
+            pass
+
+    @reg.new("foo.myothertype")
+    class MyOtherType(LogEntryType):
+        pass
+
+    typ, meta = reg.get(action_type="foo.mytype")
+    assert isinstance(typ, MyType)
+    assert meta['action_type'] == "foo.mytype"
+    assert meta['plugin'] == 'my_plugin'
+
+    typ, meta = reg.get(action_type="foo.myothertype")
+    assert isinstance(typ, MyOtherType)
+    assert meta['action_type'] == "foo.myothertype"
+    assert meta['plugin'] is None
+
+    by_my_plugin = reg.filter(plugin='my_plugin')
+    assert set(type(typ) for typ, meta in by_my_plugin) == {MyType}
+
+
+def test_logentrytype_registry_validation():
+    reg = LogEntryTypeRegistry()
+
+    with pytest.raises(TypeError, match='Must not register base classes, only derived ones'):
+        reg.register(LogEntryType("foo.mytype"))
+
+    with pytest.raises(TypeError, match='Must not register base classes, only derived ones'):
+        reg.new_from_dict({"foo.mytype": "My Log Entry"})(ItemLogEntryType)
+
+    with pytest.raises(TypeError, match='Entries must be derived from LogEntryType'):
+        @reg.new()
+        class MyType:
+            pass