Refactor group and music game models to use UniqueConstraint; update form error handling in templates

game/models.py

@@ -1,5 +1,6 @@
 from django.contrib.auth.models import User
 from django.db import models
+from django.db.models.functions import Lower
 from django.urls import reverse
 
 
@@ -19,7 +20,9 @@ class Group(models.Model):
         return reverse("group_detail", kwargs={"pk": self.pk})
 
     class Meta:
-        unique_together = ["name", "owner"]
+        constraints = [
+            models.UniqueConstraint(Lower("name"), "owner", name="unique_group_name")
+        ]
 
 
 class MusicVideo(models.Model):
@@ -31,7 +34,11 @@ class MusicVideo(models.Model):
     blacklisted = models.BooleanField(default=False)
 
     class Meta:
-        unique_together = ["yt_id", "owner", "group"]
+        constraints = [
+            models.UniqueConstraint(
+                fields=("yt_id", "owner", "group"), name="unique_music_in_group"
+            )
+        ]
 
 
 class MusikGame(models.Model):
@@ -52,5 +59,10 @@ class MusicGameOrder(models.Model):
     order = models.PositiveIntegerField()
 
     class Meta:
-        unique_together = [["game", "player", "music_video"], ["game", "order"]]
+        constraints = [
+            models.UniqueConstraint(
+                fields=("game", "player", "music_video"), name="unique_music_in_game"
+            ),
+            models.UniqueConstraint(fields=("game", "order"), name="unique_order"),
+        ]
         ordering = ["order"]