Add setting to allow or prohibit duplicate IPN values

InvenTree/part/models.py

@@ -529,6 +529,18 @@ class Part(MPTTModel):
         """
         super().validate_unique(exclude)
 
+        # User can decide whether duplicate IPN (Internal Part Number) values are allowed
+        allow_duplicate_ipn = common.models.InvenTreeSetting.get_setting('PART_ALLOW_DUPLICATE_IPN')
+
+        if not allow_duplicate_ipn:
+            parts = Part.objects.filter(IPN__iexact=self.IPN)
+            parts = parts.exclude(pk=self.pk)
+
+            if parts.exists():
+                raise ValidationError({
+                    'IPN': _('Duplicate IPN not allowed in part settings'),
+                })
+
         # Part name uniqueness should be case insensitive
         try:
             parts = Part.objects.exclude(id=self.id).filter(

InvenTree/part/test_part.py

@@ -249,3 +249,28 @@ class PartSettingsTest(TestCase):
             self.assertEqual(part.trackable, val)
     
             Part.objects.filter(pk=part.pk).delete()
+
+    def test_duplicate_ipn(self):
+        """
+        Test the setting which controls duplicate IPN values
+        """
+
+        # Create a part
+        Part.objects.create(name='Hello', description='A thing', IPN='IPN123')
+
+        # Attempt to create a duplicate item (should fail)
+        with self.assertRaises(ValidationError):
+            Part.objects.create(name='Hello', description='A thing', IPN='IPN123')
+
+        # Attempt to create item with duplicate IPN (should be allowed by default)
+        Part.objects.create(name='Hello', description='A thing', IPN='IPN123', revision='B')
+
+        # And attempt again with the same values (should fail)
+        with self.assertRaises(ValidationError):
+            Part.objects.create(name='Hello', description='A thing', IPN='IPN123', revision='B')
+
+        # Now update the settings so duplicate IPN values are *not* allowed
+        InvenTreeSetting.set_setting('PART_ALLOW_DUPLICATE_IPN', False, self.user)
+
+        with self.assertRaises(ValidationError):
+            Part.objects.create(name='Hello', description='A thing', IPN='IPN123', revision='C')