Prevent deletion of part which is used in an assembly (#7260)

* Prevent deletion of part which is used in an assembly

* add 'validate_model_deletion' option to ValidationMixin plugun

* Add global setting to control part delete behaviour

* Update settings location

* Unit test updates

* Further unit test updates

* Fix typos

src/backend/InvenTree/InvenTree/models.py

@@ -122,6 +122,20 @@ class PluginValidationMixin(DiffMixin):
         self.run_plugin_validation()
         super().save(*args, **kwargs)
 
+    def delete(self):
+        """Run plugin validation on model delete.
+
+        Allows plugins to prevent model instances from being deleted.
+
+        Note: Each plugin may raise a ValidationError to prevent deletion.
+        """
+        from plugin.registry import registry
+
+        for plugin in registry.with_mixin('validation'):
+            plugin.validate_model_deletion(self)
+
+        super().delete()
+
 
 class MetadataMixin(models.Model):
     """Model mixin class which adds a JSON metadata field to a model, for use by any (and all) plugins.

src/backend/InvenTree/common/models.py

@@ -1436,6 +1436,12 @@ class InvenTreeSetting(BaseInvenTreeSetting):
             'validator': bool,
             'default': True,
         },
+        'PART_ALLOW_DELETE_FROM_ASSEMBLY': {
+            'name': _('Allow Deletion from Assembly'),
+            'description': _('Allow deletion of parts which are used in an assembly'),
+            'validator': bool,
+            'default': False,
+        },
         'PART_IPN_REGEX': {
             'name': _('IPN Regex'),
             'description': _('Regular expression pattern for matching Part IPN'),

src/backend/InvenTree/company/tests.py

@@ -286,7 +286,11 @@ class ManufacturerPartSimpleTest(TestCase):
 
     def test_delete(self):
         """Test deletion of a ManufacturerPart."""
-        Part.objects.get(pk=self.part.id).delete()
+        part = Part.objects.get(pk=self.part.id)
+        part.active = False
+        part.save()
+        part.delete()
+
         # Check that ManufacturerPart was deleted
         self.assertEqual(ManufacturerPart.objects.count(), 3)
 

src/backend/InvenTree/part/api.py

@@ -1446,21 +1446,6 @@ class PartChangeCategory(CreateAPI):
 class PartDetail(PartMixin, RetrieveUpdateDestroyAPI):
     """API endpoint for detail view of a single Part object."""
 
-    def destroy(self, request, *args, **kwargs):
-        """Delete a Part instance via the API.
-
-        - If the part is 'active' it cannot be deleted
-        - It must first be marked as 'inactive'
-        """
-        part = Part.objects.get(pk=int(kwargs['pk']))
-        # Check if inactive
-        if not part.active:
-            # Delete
-            return super(PartDetail, self).destroy(request, *args, **kwargs)
-        # Return 405 error
-        message = 'Part is active: cannot delete'
-        return Response(status=status.HTTP_405_METHOD_NOT_ALLOWED, data=message)
-
     def update(self, request, *args, **kwargs):
         """Custom update functionality for Part instance.
 

src/backend/InvenTree/part/models.py

@@ -448,6 +448,27 @@ class Part(
 
         return context
 
+    def delete(self, **kwargs):
+        """Custom delete method for the Part model.
+
+        Prevents deletion of a Part if any of the following conditions are met:
+
+        - The part is still active
+        - The part is used in a BOM for a different part.
+        """
+        if self.active:
+            raise ValidationError(_('Cannot delete this part as it is still active'))
+
+        if not common.models.InvenTreeSetting.get_setting(
+            'PART_ALLOW_DELETE_FROM_ASSEMBLY', cache=False
+        ):
+            if BomItem.objects.filter(sub_part=self).exists():
+                raise ValidationError(
+                    _('Cannot delete this part as it is used in an assembly')
+                )
+
+        super().delete()
+
     def save(self, *args, **kwargs):
         """Overrides the save function for the Part model.
 

src/backend/InvenTree/part/test_api.py

@@ -1408,7 +1408,7 @@ class PartDetailTests(PartAPITestBase):
         response = self.delete(url)
 
         # As the part is 'active' we cannot delete it
-        self.assertEqual(response.status_code, 405)
+        self.assertEqual(response.status_code, 400)
 
         # So, let's make it not active
         response = self.patch(url, {'active': False}, expected_code=200)
@@ -2586,6 +2586,8 @@ class PartInternalPriceBreakTest(InvenTreeAPITestCase):
         p.active = False
         p.save()
 
+        InvenTreeSetting.set_setting('PART_ALLOW_DELETE_FROM_ASSEMBLY', True)
+
         response = self.delete(reverse('api-part-detail', kwargs={'pk': 1}))
         self.assertEqual(response.status_code, 204)
 

src/backend/InvenTree/part/test_bom_item.py

@@ -187,6 +187,8 @@ class BomItemTest(TestCase):
         self.assertEqual(bom_item.substitutes.count(), 4)
 
         for sub in subs:
+            sub.active = False
+            sub.save()
             sub.delete()
 
         # The substitution links should have been automatically removed

src/backend/InvenTree/part/test_part.py

@@ -336,6 +336,8 @@ class PartTest(TestCase):
         self.assertIn(self.r1, r2_relations)
 
         # Delete a part, ensure the relationship also gets deleted
+        self.r1.active = False
+        self.r1.save()
         self.r1.delete()
 
         self.assertEqual(PartRelated.objects.count(), countbefore)
@@ -351,6 +353,8 @@ class PartTest(TestCase):
         self.assertEqual(len(self.r2.get_related_parts()), n)
 
         # Deleting r2 should remove *all* newly created relationships
+        self.r2.active = False
+        self.r2.save()
         self.r2.delete()
         self.assertEqual(PartRelated.objects.count(), countbefore)
 

src/backend/InvenTree/plugin/base/integration/ValidationMixin.py

@@ -49,6 +49,23 @@ class ValidationMixin:
         """Raise a ValidationError with the given message."""
         raise ValidationError(message)
 
+    def validate_model_deletion(self, instance):
+        """Run custom validation when a model instance is being deleted.
+
+        This method is called when a model instance is being deleted.
+        It allows the plugin to raise a ValidationError if the instance cannot be deleted.
+
+        Arguments:
+            instance: The model instance to validate
+
+        Returns:
+            None or True (refer to class docstring)
+
+        Raises:
+            ValidationError if the instance cannot be deleted
+        """
+        return None
+
     def validate_model_instance(self, instance, deltas=None):
         """Run custom validation on a database model instance.
 

src/backend/InvenTree/templates/InvenTree/settings/part.html

@@ -15,6 +15,7 @@
         {% include "InvenTree/settings/setting.html" with key="PART_IPN_REGEX" %}
         {% include "InvenTree/settings/setting.html" with key="PART_ALLOW_DUPLICATE_IPN" %}
         {% include "InvenTree/settings/setting.html" with key="PART_ALLOW_EDIT_IPN" %}
+        {% include "InvenTree/settings/setting.html" with key="PART_ALLOW_DELETE_FROM_ASSEMBLY" %}
         {% include "InvenTree/settings/setting.html" with key="PART_NAME_FORMAT" %}
         {% include "InvenTree/settings/setting.html" with key="PART_SHOW_RELATED" icon="fa-random" %}
         {% include "InvenTree/settings/setting.html" with key="PART_CREATE_INITIAL" icon="fa-boxes" %}

src/frontend/src/components/forms/ApiForm.tsx

@@ -497,7 +497,7 @@ export function ApiForm({
             {/* Form Fields */}
             <Stack gap="sm">
               {(!isValid || nonFieldErrors.length > 0) && (
-                <Alert radius="sm" color="red" title={t`Form Errors Exist`}>
+                <Alert radius="sm" color="red" title={t`Error`}>
                   {nonFieldErrors.length > 0 && (
                     <Stack gap="xs">
                       {nonFieldErrors.map((message) => (

src/frontend/src/pages/Index/Settings/SystemSettings.tsx

@@ -173,6 +173,7 @@ export default function SystemSettings() {
               'PART_IPN_REGEX',
               'PART_ALLOW_DUPLICATE_IPN',
               'PART_ALLOW_EDIT_IPN',
+              'PART_ALLOW_DELETE_FROM_ASSEMBLY',
               'PART_NAME_FORMAT',
               'PART_SHOW_RELATED',
               'PART_CREATE_INITIAL',