Add new signal logentry_object_link

doc/development/api/general.rst

@@ -51,7 +51,7 @@ Backend
 
 
 .. automodule:: pretix.base.signals
-   :members: logentry_display, requiredaction_display
+   :members: logentry_display, logentry_object_link, requiredaction_display
 
 Vouchers
 """"""""

doc/development/api/plugins.rst

@@ -114,6 +114,19 @@ method to make your receivers available::
         def ready(self):
             from . import signals  # NOQA
 
+You can optionally specify code that is executed when your plugin is activated for an event
+in the ``installed`` method::
+
+    class PaypalApp(AppConfig):
+        …
+
+        def installed(self, event):
+            pass  # Your code here
+
+
+Note that ``installed`` will *not* be called if the plugin in indirectly activated for an event
+because the event is created with settings copied from another event.
+
 Views
 -----
 

src/pretix/base/models/log.py

@@ -8,6 +8,8 @@ from django.utils.functional import cached_property
 from django.utils.html import escape
 from django.utils.translation import pgettext_lazy, ugettext_lazy as _
 
+from pretix.base.signals import logentry_object_link
+
 
 class LogEntry(models.Model):
     """
@@ -146,6 +148,9 @@ class LogEntry(models.Model):
         elif a_text:
             return a_text
         else:
+            for receiver, response in logentry_object_link.send(self.event, logentry=self):
+                if response:
+                    return response
             return ''
 
     @cached_property

src/pretix/base/signals.py

@@ -166,6 +166,34 @@ 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.
 """
 
+logentry_object_link = EventPluginSignal(
+    providing_args=["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.
+"""
+
 requiredaction_display = EventPluginSignal(
     providing_args=["action", "request"]
 )

src/pretix/control/views/event.py

@@ -205,6 +205,10 @@ class EventPlugins(EventSettingsViewMixin, EventPermissionRequiredMixin, Templat
                         if getattr(plugins_available[module], 'restricted', False):
                             if not request.user.is_superuser:
                                 continue
+
+                        if hasattr(plugins_available[module].app, 'installed'):
+                            getattr(plugins_available[module].app, 'installed')(self.request.event)
+
                         self.request.event.log_action('pretix.event.plugins.enabled', user=self.request.user,
                                                       data={'plugin': module})
                         if module not in plugins_active: