Fix #526 -- Add a webhook system (#1073)

- [x] Data model
- [x] UI
- [x] Fire hooks
- [x] Unit tests
- [x] Display logs
- [x] API to modify hooks
- [x] Documentation
- [x] More hooks!

src/pretix/api/serializers/webhooks.py

@@ -0,0 +1,71 @@
+from django.core.exceptions import ValidationError
+from rest_framework import serializers
+
+from pretix.api.models import WebHook
+from pretix.api.serializers.i18n import I18nAwareModelSerializer
+from pretix.api.webhooks import get_all_webhook_events
+from pretix.base.models import Event
+
+
+class EventRelatedField(serializers.SlugRelatedField):
+    def get_queryset(self):
+        return self.context['organizer'].events.all()
+
+
+class ActionTypesField(serializers.Field):
+    def to_representation(self, instance: WebHook):
+        return instance.action_types
+
+    def to_internal_value(self, data):
+        types = get_all_webhook_events()
+        for d in data:
+            if d not in types:
+                raise ValidationError('Invalid action type "%s".' % d)
+        return {'action_types': data}
+
+
+class WebHookSerializer(I18nAwareModelSerializer):
+    limit_events = EventRelatedField(
+        slug_field='slug',
+        queryset=Event.objects.none(),
+        many=True
+    )
+    action_types = ActionTypesField(source='*')
+
+    class Meta:
+        model = WebHook
+        fields = ('id', 'enabled', 'target_url', 'all_events', 'limit_events', 'action_types')
+
+    def validate(self, data):
+        data = super().validate(data)
+
+        full_data = self.to_internal_value(self.to_representation(self.instance)) if self.instance else {}
+        full_data.update(data)
+
+        for event in full_data.get('limit_events'):
+            if self.context['organizer'] != event.organizer:
+                raise ValidationError('One or more events do not belong to this organizer.')
+
+        if full_data.get('limit_events') and full_data.get('all_events'):
+            raise ValidationError('You can set either limit_events or all_events.')
+
+        return data
+
+    def create(self, validated_data):
+        action_types = validated_data.pop('action_types')
+        inst = super().create(validated_data)
+        for l in action_types:
+            inst.listeners.create(action_type=l)
+        return inst
+
+    def update(self, instance, validated_data):
+        action_types = validated_data.pop('action_types', None)
+        instance = super().update(instance, validated_data)
+        if action_types is not None:
+            current_listeners = set(instance.listeners.values_list('action_type', flat=True))
+            new_listeners = set(action_types)
+            for l in current_listeners - new_listeners:
+                instance.listeners.filter(action_type=l).delete()
+            for l in new_listeners - current_listeners:
+                instance.listeners.create(action_type=l)
+        return instance