update admin view of event

fet2020/posts/models.py

@@ -239,6 +239,9 @@ class Event(Post):
     class Meta:
         proxy = True
 
+        verbose_name = "Event"
+        verbose_name_plural = "Events"
+
     @property
     def event_start_month(self):
         return self.event_start.strftime("%b")
@@ -247,6 +250,12 @@ class Event(Post):
     def event_start_day(self):
         return self.event_start.strftime("%d")
 
+    def clean(self):
+        if self.event_end is None or self.event_start is None:
+            raise ValidationError(_('Das Datum des Events fehlt.'))
+        elif self.event_end < self.event_start:
+            raise ValidationError(_('Das Ende des Events liegt vor dem Beginn.'))
+
     def save(self, *args, **kwargs):
         self.is_event = True
 
@@ -266,6 +275,9 @@ class FetMeeting(Event):
         verbose_name_plural = "Fet Sitzungen"
 
     def clean(self):
+        if self.event_start is None:
+            raise ValidationError(_('Das Datum des Events fehlt.'))
+
         slug = slugify(self.event_start.date()) + "-" + slugify("Fachschaftssitzung")
 
         if Post.objects.filter(slug=slug).count() != 0: