Allow to configure a readonly DB connection

src/pretix/api/serializers/fields.py

@@ -115,10 +115,10 @@ class PluginsField(serializers.Field):
 
     def to_representation(self, obj):
         from pretix.base.plugins import get_all_plugins
-        active_plugins = set(obj.get_plugins())
+
         return sorted([
             p.module for p in get_all_plugins()
-            if not p.name.startswith('.') and getattr(p, 'visible', True) and p.module in active_plugins
+            if not p.name.startswith('.') and getattr(p, 'visible', True) and p.module in obj.get_plugins()
         ])
 
     def to_internal_value(self, data):

src/pretix/base/exporters/orderlist.py

@@ -315,9 +315,8 @@ class OrderListExporter(MultiSheetListExporter):
             for id, vn in payment_methods:
                 headers.append(_('Paid by {method}').format(method=vn))
 
-        if self.event_object_cache:
-            # get meta_data labels from first cached event if any
-            headers += next(iter(self.event_object_cache.values())).meta_data.keys()
+        # get meta_data labels from first cached event
+        headers += next(iter(self.event_object_cache.values())).meta_data.keys()
         yield headers
 
         full_fee_sum_cache = {
@@ -504,9 +503,8 @@ class OrderListExporter(MultiSheetListExporter):
         headers.append(_('External customer ID'))
         headers.append(_('Payment providers'))
 
-        if self.event_object_cache:
-            # get meta_data labels from first cached event if any
-            headers += next(iter(self.event_object_cache.values())).meta_data.keys()
+        # get meta_data labels from first cached event
+        headers += next(iter(self.event_object_cache.values())).meta_data.keys()
         yield headers
 
         yield self.ProgressSetTotal(total=qs.count())
@@ -709,9 +707,9 @@ class OrderListExporter(MultiSheetListExporter):
             _('Position order link')
         ]
 
+        # get meta_data labels from first cached event
+        meta_data_labels = next(iter(self.event_object_cache.values())).meta_data.keys()
         if has_subevents:
-            # get meta_data labels from first cached event
-            meta_data_labels = next(iter(self.event_object_cache.values())).meta_data.keys()
             headers += meta_data_labels
         yield headers
 

src/pretix/base/plugins.py

@@ -49,39 +49,14 @@ class PluginType(Enum):
     EXPORT = 4
 
 
-def plugin_is_available(meta, event=None, organizer=None):
-    if not hasattr(meta.app, 'is_available'):
-        return True
-
-    level = getattr(meta, "level", PLUGIN_LEVEL_EVENT)
-    if level == PLUGIN_LEVEL_EVENT:
-        if event:
-            return meta.app.is_available(event)
-        elif organizer:
-            if not hasattr(organizer, '_plugin_availability_fallback_event'):
-                with scope(organizer=organizer):
-                    setattr(organizer, '_plugin_availability_fallback_event', organizer.events.first())
-            return (
-                organizer._plugin_availability_fallback_event
-                and meta.app.is_available(organizer._plugin_availability_fallback_event)
-            )
-    elif level == PLUGIN_LEVEL_ORGANIZER:
-        if organizer:
-            return meta.app.is_available(organizer)
-        elif event:
-            return meta.app.is_available(event.organizer)
-    elif level == PLUGIN_LEVEL_EVENT_ORGANIZER_HYBRID and (event or organizer):
-        return meta.app.is_available(event or organizer)
-
-    return True
-
-
 def get_all_plugins(*, event=None, organizer=None) -> List[type]:
     """
     Returns the PretixPluginMeta classes of all plugins found in the installed Django apps.
     """
     assert not event or not organizer
     plugins = []
+    event_fallback = None
+    event_fallback_used = False
     for app in apps.get_app_configs():
         if hasattr(app, 'PretixPluginMeta'):
             meta = app.PretixPluginMeta
@@ -90,8 +65,28 @@ def get_all_plugins(*, event=None, organizer=None) -> List[type]:
             if app.name in settings.PRETIX_PLUGINS_EXCLUDE:
                 continue
 
-            if not plugin_is_available(meta, event, organizer):
-                continue
+            level = getattr(meta, "level", PLUGIN_LEVEL_EVENT)
+            if level == PLUGIN_LEVEL_EVENT:
+                if event and hasattr(app, 'is_available'):
+                    if not app.is_available(event):
+                        continue
+                elif organizer and hasattr(app, 'is_available'):
+                    if not event_fallback_used:
+                        with scope(organizer=organizer):
+                            event_fallback = organizer.events.first()
+                        event_fallback_used = True
+                    if not event_fallback or not app.is_available(event_fallback):
+                        continue
+            elif level == PLUGIN_LEVEL_ORGANIZER:
+                if organizer and hasattr(app, 'is_available'):
+                    if not app.is_available(organizer):
+                        continue
+                elif event and hasattr(app, 'is_available'):
+                    if not app.is_available(event.organizer):
+                        continue
+            elif level == PLUGIN_LEVEL_EVENT_ORGANIZER_HYBRID and (event or organizer) and hasattr(app, 'is_available'):
+                if not app.is_available(event or organizer):
+                    continue
 
             plugins.append(meta)
     return sorted(

src/pretix/control/views/organizer.py

@@ -100,7 +100,7 @@ from pretix.base.models.organizer import SalesChannel, TeamAPIToken
 from pretix.base.payment import PaymentException
 from pretix.base.plugins import (
     PLUGIN_LEVEL_EVENT, PLUGIN_LEVEL_EVENT_ORGANIZER_HYBRID,
-    PLUGIN_LEVEL_ORGANIZER, plugin_is_available,
+    PLUGIN_LEVEL_ORGANIZER,
 )
 from pretix.base.services.export import multiexport, scheduled_organizer_export
 from pretix.base.services.mail import mail, prefix_subject
@@ -597,13 +597,6 @@ class OrganizerCreate(CreateView):
         })
 
 
-def available_plugins(organizer):
-    from pretix.base.plugins import get_all_plugins
-
-    return (p for p in get_all_plugins(organizer=organizer) if not p.name.startswith('.')
-            and getattr(p, 'visible', True))
-
-
 class OrganizerPlugins(OrganizerDetailViewMixin, OrganizerPermissionRequiredMixin, TemplateView, SingleObjectMixin):
     model = Organizer
     context_object_name = 'organizer'
@@ -613,6 +606,12 @@ class OrganizerPlugins(OrganizerDetailViewMixin, OrganizerPermissionRequiredMixi
     def get_object(self, queryset=None) -> Organizer:
         return self.request.organizer
 
+    def available_plugins(self, organizer):
+        from pretix.base.plugins import get_all_plugins
+
+        return (p for p in get_all_plugins(organizer=organizer) if not p.name.startswith('.')
+                and getattr(p, 'visible', True))
+
     def prepare_links(self, pluginmeta, key):
         links = getattr(pluginmeta, key, [])
         try:
@@ -638,7 +637,7 @@ class OrganizerPlugins(OrganizerDetailViewMixin, OrganizerPermissionRequiredMixi
         from pretix.base.plugins import CATEGORY_LABELS, CATEGORY_ORDER
 
         context = super().get_context_data(*args, **kwargs)
-        plugins = list(available_plugins(self.object))
+        plugins = list(self.available_plugins(self.object))
 
         active_counter = Counter()
         events_total = 0
@@ -686,7 +685,7 @@ class OrganizerPlugins(OrganizerDetailViewMixin, OrganizerPermissionRequiredMixi
         self.object = self.get_object()
 
         plugins_available = {
-            p.module: p for p in available_plugins(self.object)
+            p.module: p for p in self.available_plugins(self.object)
         }
         choose_events_next = False
         with transaction.atomic():
@@ -787,6 +786,12 @@ class OrganizerPluginEvents(OrganizerDetailViewMixin, OrganizerPermissionRequire
         }
         return kwargs
 
+    def available_plugins(self, organizer):
+        from pretix.base.plugins import get_all_plugins
+
+        return (p for p in get_all_plugins(organizer=organizer) if not p.name.startswith('.')
+                and getattr(p, 'visible', True))
+
     def get_context_data(self, **kwargs):
         return super().get_context_data(
             plugin=self.plugin,
@@ -794,10 +799,12 @@ class OrganizerPluginEvents(OrganizerDetailViewMixin, OrganizerPermissionRequire
         )
 
     def dispatch(self, request, *args, **kwargs):
-        try:
-            self.plugin = next(p for p in available_plugins(self.request.organizer) if p.module == kwargs["plugin"])
-        except StopIteration:
+        plugins_available = {
+            p.module: p for p in self.available_plugins(self.request.organizer)
+        }
+        if kwargs["plugin"] not in plugins_available:
             raise Http404(_("Unknown plugin."))
+        self.plugin = plugins_available[kwargs["plugin"]]
         level = getattr(self.plugin, "level", PLUGIN_LEVEL_EVENT)
         if level == PLUGIN_LEVEL_ORGANIZER:
             raise Http404(_("This plugin can only be enabled for the entire organizer account."))
@@ -828,9 +835,6 @@ class OrganizerPluginEvents(OrganizerDetailViewMixin, OrganizerPermissionRequire
         logentries_to_save = []
 
         for e in self.request.organizer.events.filter(pk__in=events_to_enable):
-            if not plugin_is_available(self.plugin, organizer=self.request.organizer, event=e):
-                messages.warning(self.request, _("This plugin cannot be activated for event {}.").format(e.name))
-                continue
             logentries_to_save.append(
                 e.log_action('pretix.event.plugins.enabled', user=self.request.user, data={'plugin': self.plugin.module}, save=False)
             )

src/pretix/settings.py

@@ -157,7 +157,7 @@ DATABASES = {
         'HOST': config.get('database', 'host', fallback=''),
         'PORT': config.get('database', 'port', fallback=''),
         'CONN_MAX_AGE': 0 if db_backend == 'sqlite3' else 120,
-        'CONN_HEALTH_CHECKS': db_backend != 'sqlite3',  # Will only be used from Django 4.1 onwards
+        'CONN_HEALTH_CHECKS': db_backend != 'sqlite3',
         'DISABLE_SERVER_SIDE_CURSORS': db_disable_server_side_cursors,
         'OPTIONS': db_options,
         'TEST': {}
@@ -179,6 +179,21 @@ if config.has_section('replica'):
     }
     DATABASE_ROUTERS = ['pretix.helpers.database.ReplicaRouter']
 
+if config.has_section('dbreadonly'):
+    DATABASES['readonly'] = {
+        'ENGINE': 'django.db.backends.' + db_backend,
+        'NAME': config.get('dbreadonly', 'name', fallback=DATABASES['default']['NAME']),
+        'USER': config.get('dbreadonly', 'user', fallback=DATABASES['default']['USER']),
+        'PASSWORD': config.get('dbreadonly', 'password', fallback=DATABASES['default']['PASSWORD']),
+        'HOST': config.get('dbreadonly', 'host', fallback=DATABASES['default']['HOST']),
+        'PORT': config.get('dbreadonly', 'port', fallback=DATABASES['default']['PORT']),
+        'CONN_MAX_AGE': 0,  # do not spam primary with open connections as long as readonly is only used occasionally
+        'CONN_HEALTH_CHECKS': db_backend != 'sqlite3',
+        'DISABLE_SERVER_SIDE_CURSORS': db_disable_server_side_cursors,
+        'OPTIONS': db_options,
+        'TEST': {}
+    }
+
 STATIC_URL = config.get('urls', 'static', fallback='/static/')
 
 MEDIA_URL = config.get('urls', 'media', fallback='/media/')