Add unique constraint for memberships

leaderboards/migrations/0021_membership_unique_memberships.py

@@ -0,0 +1,19 @@
+# Generated by Django 4.2.11 on 2024-05-31 14:28
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("leaderboards", "0020_membershipscore_performance_total_and_more"),
+    ]
+
+    operations = [
+        migrations.AddConstraint(
+            model_name="membership",
+            constraint=models.UniqueConstraint(
+                fields=("leaderboard_id", "user_id"), name="unique_memberships"
+            ),
+        ),
+    ]

leaderboards/models.py

@@ -200,6 +200,12 @@ def __str__(self):
         return f"{self.leaderboard}: {self.user.username}"
 
     class Meta:
+        constraints = [
+            models.UniqueConstraint(
+                fields=["leaderboard_id", "user_id"], name="unique_memberships"
+            )
+        ]
+
         indexes = [models.Index(fields=["leaderboard"]), models.Index(fields=["user"])]