Move middleware functionality to utils.py (#154)

This simplifies providing an `event_view` method which works as
decorator for presale/ views (e.g. for plugins), providing passing
requests with event and organizer context if possible, and re-routing or
failing appropriately otherwise.

doc/development/setup.rst

@@ -85,7 +85,7 @@ Before you check in your code into git, always run the static checkers and unit
 
     flake8 .
     isort -c -rc .
-    python manage.py validate
+    python manage.py check
     py.test
 
 The ``flake8`` command by default is a bit stricter than what we really enforce, but we do enforce that all commits

src/pretix/presale/middleware.py

@@ -1,14 +1,6 @@
-from urllib.parse import urljoin
-
-from django.core.exceptions import PermissionDenied
 from django.core.urlresolvers import resolve
-from django.http import Http404
-from django.shortcuts import redirect
-from django.utils.translation import ugettext_lazy as _
 
-from pretix.base.middleware import LocaleMiddleware
-from pretix.base.models import Event, EventPermission, Organizer
-from pretix.multidomain.urlreverse import get_domain
+from .utils import _detect_event
 
 
 class EventMiddleware:
@@ -19,54 +11,9 @@ class EventMiddleware:
             return
 
         if 'organizer' in url.kwargs or 'event' in url.kwargs:
-            try:
-                if hasattr(request, 'organizer'):
-                    # We are on an organizer's custom domain
-                    if 'organizer' in url.kwargs and url.kwargs['organizer']:
-                        if url.kwargs['organizer'] != request.organizer.slug:
-                            raise Http404(_('The selected event was not found.'))
-                        path = "/" + request.get_full_path().split("/", 2)[-1]
-                        return redirect(path)
-
-                    request.event = Event.objects.filter(
-                        slug=url.kwargs['event'],
-                        organizer=request.organizer,
-                    ).select_related('organizer')[0]
-                    request.organizer = request.event.organizer
-                else:
-                    # We are on our main domain
-                    if 'event' in url.kwargs and 'organizer' in url.kwargs:
-                        request.event = Event.objects.filter(
-                            slug=url.kwargs['event'],
-                            organizer__slug=url.kwargs['organizer']
-                        ).select_related('organizer')[0]
-                        request.organizer = request.event.organizer
-                    elif 'organizer' in url.kwargs:
-                        request.organizer = Organizer.objects.filter(
-                            slug=url.kwargs['organizer']
-                        )[0]
-                    else:
-                        raise Http404()
-
-                    # If this organizer has a custom domain, send the user there
-                    domain = get_domain(request.organizer)
-                    if domain:
-                        if request.port and request.port not in (80, 443):
-                            domain = '%s:%d' % (domain, request.port)
-                        path = request.get_full_path().split("/", 2)[-1]
-                        return redirect(urljoin('%s://%s' % (request.scheme, domain), path))
-
-                if hasattr(request, 'event'):
-                    # Restrict locales to the ones available for this event
-                    LocaleMiddleware().process_request(request)
-
-                    if not request.event.live:
-                        if not request.user.is_authenticated() or not EventPermission.objects.filter(
-                                event=request.event, user=request.user).exists():
-                            raise PermissionDenied(_('The selected ticket shop is currently not available.'))
-
-            except IndexError:
-                raise Http404(_('The selected event or organizer was not found.'))
+            redirect = _detect_event(request)
+            if redirect:
+                return redirect
 
         if '_' not in request.session:
             # We need to create session even if we do not yet store something there, because we need the session

src/pretix/presale/utils.py

@@ -0,0 +1,79 @@
+from urllib.parse import urljoin
+
+from django.core.exceptions import PermissionDenied
+from django.core.urlresolvers import resolve
+from django.http import Http404
+from django.shortcuts import redirect
+from django.utils.translation import ugettext_lazy as _
+
+from pretix.base.middleware import LocaleMiddleware
+from pretix.base.models import Event, EventPermission, Organizer
+from pretix.multidomain.urlreverse import get_domain
+
+
+def _detect_event(request):
+    url = resolve(request.path_info)
+    try:
+        if hasattr(request, 'organizer'):
+            # We are on an organizer's custom domain
+            if 'organizer' in url.kwargs and url.kwargs['organizer']:
+                if url.kwargs['organizer'] != request.organizer.slug:
+                    raise Http404(_('The selected event was not found.'))
+                path = "/" + request.get_full_path().split("/", 2)[-1]
+                return redirect(path)
+
+            request.event = Event.objects\
+                .select_related('organizer')\
+                .get(
+                    slug=url.kwargs['event'],
+                    organizer=request.organizer,
+                )
+            request.organizer = request.event.organizer
+        else:
+            # We are on our main domain
+            if 'event' in url.kwargs and 'organizer' in url.kwargs:
+                request.event = Event.objects\
+                    .select_related('organizer')\
+                    .get(
+                        slug=url.kwargs['event'],
+                        organizer__slug=url.kwargs['organizer']
+                    )
+                request.organizer = request.event.organizer
+            elif 'organizer' in url.kwargs:
+                request.organizer = Organizer.objects.get(
+                    slug=url.kwargs['organizer']
+                )
+            else:
+                raise Http404()
+
+            # If this organizer has a custom domain, send the user there
+            domain = get_domain(request.organizer)
+            if domain:
+                if request.port and request.port not in (80, 443):
+                    domain = '%s:%d' % (domain, request.port)
+                path = request.get_full_path().split("/", 2)[-1]
+                return redirect(urljoin('%s://%s' % (request.scheme, domain), path))
+
+        if hasattr(request, 'event'):
+            # Restrict locales to the ones available for this event
+            LocaleMiddleware().process_request(request)
+
+            if not request.event.live:
+                if not request.user.is_authenticated() or not EventPermission.objects.filter(
+                        event=request.event, user=request.user).exists():
+                    raise PermissionDenied(_('The selected ticket shop is currently not available.'))
+
+    except Event.DoesNotExist:
+        raise Http404(_('The selected event was not found.'))
+    except Organizer.DoesNotExist:
+        raise Http404(_('The selected organizer was not found.'))
+
+
+def event_view(func):
+    def wrap(request, *args, **kwargs):
+        ret = _detect_event(request)
+        if ret:
+            return ret
+        else:
+            return func(request=request, *args, **kwargs)
+    return wrap