Enforce uniqueness constraint

InvenTree/part/migrations/0017_auto_20190505_0848.py

@@ -0,0 +1,19 @@
+# Generated by Django 2.2 on 2019-05-04 22:48
+
+from django.conf import settings
+from django.db import migrations
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        migrations.swappable_dependency(settings.AUTH_USER_MODEL),
+        ('part', '0016_partstar'),
+    ]
+
+    operations = [
+        migrations.AlterUniqueTogether(
+            name='partstar',
+            unique_together={('part', 'user')},
+        ),
+    ]

InvenTree/part/models.py

@@ -439,6 +439,9 @@ class PartStar(models.Model):
 
     user = models.ForeignKey(User, on_delete=models.CASCADE, related_name='starred_parts')
 
+    class Meta:
+        unique_together = ['part', 'user']
+
 
 class BomItem(models.Model):
     """ A BomItem links a part to its component items.