Fix #1378 -- API: Allow to access and modify (some) event setti… (#1569)

* API: Allow to access event settings

* Convert most "general" settings

* Smaller fixes

* Add more settings

* Relative dates, nulling

* Fix a test failure

* Fix wrong attribute access

src/pretix/base/__init__.py

@@ -1,5 +1,4 @@
 from django.apps import AppConfig
-from django.conf import settings
 
 
 class PretixBaseConfig(AppConfig):
@@ -14,6 +13,7 @@ class PretixBaseConfig(AppConfig):
         from . import notifications  # NOQA
         from . import email  # NOQA
         from .services import auth, checkin, export, mail, tickets, cart, orderimport, orders, invoices, cleanup, update_check, quotas, notifications, vouchers  # NOQA
+        from django.conf import settings
 
         try:
             from .celery_app import app as celery_app  # NOQA

src/pretix/base/forms/__init__.py

@@ -8,7 +8,6 @@ from django.utils.crypto import get_random_string
 from formtools.wizard.views import SessionWizardView
 from hierarkey.forms import HierarkeyForm
 
-from pretix.base.models import Event
 from pretix.base.reldate import RelativeDateField, RelativeDateTimeField
 
 from .validators import PlaceholderValidator  # NOQA
@@ -51,19 +50,33 @@ class I18nInlineFormSet(i18nfield.forms.I18nInlineFormSet):
 
 
 class SettingsForm(i18nfield.forms.I18nFormMixin, HierarkeyForm):
+    auto_fields = []
 
     def __init__(self, *args, **kwargs):
+        from pretix.base.settings import DEFAULTS
+
         self.obj = kwargs.get('obj', None)
         self.locales = self.obj.settings.get('locales') if self.obj else kwargs.pop('locales', None)
         kwargs['attribute_name'] = 'settings'
         kwargs['locales'] = self.locales
         kwargs['initial'] = self.obj.settings.freeze()
         super().__init__(*args, **kwargs)
+        for fname in self.auto_fields:
+            kwargs = DEFAULTS[fname].get('form_kwargs', {})
+            kwargs.setdefault('required', False)
+            field = DEFAULTS[fname]['form_class'](
+                **kwargs
+            )
+            if isinstance(field, i18nfield.forms.I18nFormField):
+                field.widget.enabled_locales = self.locales
+            self.fields[fname] = field
         for k, f in self.fields.items():
             if isinstance(f, (RelativeDateTimeField, RelativeDateField)):
                 f.set_event(self.obj)
 
     def get_new_filename(self, name: str) -> str:
+        from pretix.base.models import Event
+
         nonce = get_random_string(length=8)
         if isinstance(self.obj, Event):
             fname = '%s/%s/%s.%s.%s' % (

src/pretix/base/forms/widgets.py

@@ -6,9 +6,6 @@ from django.utils.functional import lazy
 from django.utils.timezone import now
 from django.utils.translation import ugettext_lazy as _
 
-from pretix.base.models import OrderPosition
-from pretix.multidomain.urlreverse import eventreverse
-
 
 class DatePickerWidget(forms.DateInput):
     def __init__(self, attrs=None, date_format=None):
@@ -71,6 +68,9 @@ class UploadedFileWidget(forms.ClearableFileInput):
 
         @property
         def url(self):
+            from pretix.base.models import OrderPosition
+            from pretix.multidomain.urlreverse import eventreverse
+
             if isinstance(self.position, OrderPosition):
                 return eventreverse(self.event, 'presale:event.order.download.answer', kwargs={
                     'order': self.position.order.code,

src/pretix/base/reldate.py

@@ -8,6 +8,7 @@ from django import forms
 from django.core.exceptions import ValidationError
 from django.db import models
 from django.utils.translation import ugettext_lazy as _
+from rest_framework import serializers
 
 BASE_CHOICES = (
     ('date_from', _('Event start')),
@@ -115,6 +116,8 @@ class RelativeDateWrapper:
                     base_date_name=parts[3],
                     time=time
                 )
+            if data.base_date_name not in [k[0] for k in BASE_CHOICES]:
+                raise ValueError('{} is not a valid base date'.format(data.base_date_name))
         else:
             data = parser.parse(input)
         return RelativeDateWrapper(data)
@@ -330,3 +333,39 @@ class ModelRelativeDateTimeField(models.CharField):
         defaults = {'form_class': self.form_class}
         defaults.update(kwargs)
         return super().formfield(**defaults)
+
+
+class SerializerRelativeDateField(serializers.CharField):
+
+    def to_internal_value(self, data):
+        if data is None:
+            return None
+        try:
+            r = RelativeDateWrapper.from_string(data)
+            if isinstance(r.data, RelativeDate):
+                if r.data.time is not None:
+                    raise ValidationError("Do not specify a time for a date field")
+            return r
+        except:
+            raise ValidationError("Invalid relative date")
+
+    def to_representation(self, value: RelativeDateWrapper):
+        if value is None:
+            return None
+        return value.to_string()
+
+
+class SerializerRelativeDateTimeField(serializers.CharField):
+
+    def to_internal_value(self, data):
+        if data is None:
+            return None
+        try:
+            return RelativeDateWrapper.from_string(data)
+        except:
+            raise ValidationError("Invalid relative date")
+
+    def to_representation(self, value: RelativeDateWrapper):
+        if value is None:
+            return None
+        return value.to_string()

src/pretix/base/signals.py

@@ -641,3 +641,27 @@ to define additional columns that can be read during import. You are expected to
 
 As with all event-plugin signals, the ``sender`` keyword argument will contain the event.
 """
+
+validate_event_settings = EventPluginSignal(
+    providing_args=["settings_dict"]
+)
+"""
+This signal is sent out if the user performs an update of event settings through the API or web interface.
+You are passed a ``settings_dict`` dictionary with the new state of the event settings object and are expected
+to raise a ``django.core.exceptions.ValidationError`` if the new state is not valid.
+You can not modify the dictionary. This is only recommended to use if you have multiple settings
+that can only be validated together. To validate individual settings, pass a validator to the
+serializer field instead.
+
+As with all event-plugin signals, the ``sender`` keyword argument will contain the event.
+"""
+
+api_event_settings_fields = EventPluginSignal(
+    providing_args=[]
+)
+"""
+This signal is sent out to collect serializable settings fields for the API. You are expected to
+return a dictionary mapping names of attributes in the settings store to DRF serializer field instances.
+
+As with all event-plugin signals, the ``sender`` keyword argument will contain the event.
+"""