Only require that showtimes be unique.

For whatever reason, showtime__date uniqueness was not being enforced
correctly. I don't understand why.

If possible, it'd be neat to have the other two `Show.clean()`
restrictions be enforced as constraints.

nkdsu/apps/vote/migrations/0023_show_unique_showtime_dates.py

@@ -10,7 +10,7 @@ class Migration(migrations.Migration):
         migrations.AddConstraint(
             model_name='show',
             constraint=models.UniqueConstraint(
-                models.F('showtime__date'), name='unique_showtime_dates'
+                models.F('showtime'), name='unique_showtime'
             ),
         ),
     ]

nkdsu/apps/vote/models.py

@@ -80,10 +80,7 @@ class Show(CleanOnSaveMixin, Serializable, models.Model):
 
     class Meta:
         constraints = [
-            models.UniqueConstraint(
-                'showtime__date',
-                name='unique_showtime_dates',
-            ),
+            models.UniqueConstraint('showtime', name='unique_showtime'),
         ]
         ordering = ['-showtime']
 

nkdsu/apps/vote/tests/tests.py

@@ -101,11 +101,11 @@ def test_showtime_date_constraint(self) -> None:
 
         with self.assertRaises(ValidationError) as e:
             Show.objects.create(
-                showtime='2038-01-01T16:00:00Z', end='2038-01-01T18:00:00Z'
+                showtime='2038-01-01T12:00:00Z', end='2038-01-01T12:00:00Z'
             )
         self.assertEqual(
             str(e.exception),
-            str({'__all__': ['Constraint “unique_showtime_dates” is violated.']}),
+            str({'__all__': ['Constraint “unique_showtime” is violated.']}),
         )
 
         Show.objects.create(showtime='2038-01-02T12:00:00Z', end='2038-01-02T14:00:00Z')