Refactor API filtering for endpoints

- Specify ContentType by ID, model or app label

src/backend/InvenTree/InvenTree/serializers.py

@@ -768,20 +768,31 @@ class ContentTypeField(serializers.ChoiceField):
 
         content_type = None
 
+        # First, try to resolve the content type via direct pk value
         try:
-            app_label, model = data.split('.')
-            content_types = ContentType.objects.filter(app_label=app_label, model=model)
+            content_type_id = int(data)
+            content_type = ContentType.objects.get_for_id(content_type_id)
+        except (ValueError, ContentType.DoesNotExist):
+            content_type = None
 
-            if content_types.exists() and content_types.count() == 1:
+        try:
+            if len(data.split('.')) == 2:
+                app_label, model = data.split('.')
+                content_types = ContentType.objects.filter(
+                    app_label=app_label, model=model
+                )
+
+                if content_types.count() == 1:
                     # Try exact match first
                     content_type = content_types.first()
             else:
                 # Try lookup just on model name
-                content_types = ContentType.objects.filter(model=model)
+                content_types = ContentType.objects.filter(model=data)
                 if content_types.exists() and content_types.count() == 1:
                     content_type = content_types.first()
 
-        except Exception:
+        except Exception as e:
+            print('e:', e)
             raise ValidationError(_('Invalid content type format'))
 
         if content_type is None:

src/backend/InvenTree/common/api.py

@@ -28,6 +28,7 @@ from rest_framework.permissions import IsAdminUser, IsAuthenticated
 from rest_framework.response import Response
 from rest_framework.views import APIView
 
+import common.filters
 import common.models
 import common.serializers
 import InvenTree.conversion
@@ -777,7 +778,7 @@ class ParameterTemplateFilter(FilterSet):
         """Metaclass options."""
 
         model = common.models.ParameterTemplate
-        fields = ['model_type', 'name', 'units', 'checkbox', 'enabled']
+        fields = ['name', 'units', 'checkbox', 'enabled']
 
     has_choices = rest_filters.BooleanFilter(
         method='filter_has_choices', label='Has Choice'
@@ -799,6 +800,14 @@ class ParameterTemplateFilter(FilterSet):
 
         return queryset.filter(Q(units=None) | Q(units='')).distinct()
 
+    model_type = rest_filters.CharFilter(method='filter_model_type', label='Model Type')
+
+    def filter_model_type(self, queryset, name, value):
+        """Filter queryset to include only ParameterTemplates of the given model type."""
+        return common.filters.filter_content_type(
+            queryset, 'model_type', value, allow_null=False
+        )
+
     for_model = rest_filters.CharFilter(method='filter_for_model', label='For Model')
 
     def filter_for_model(self, queryset, name, value):
@@ -807,9 +816,9 @@ class ParameterTemplateFilter(FilterSet):
         Note that this varies from the 'model_type' filter, in that ParameterTemplates
         with a blank 'model_type' are considered to apply to all models.
         """
-        return queryset.filter(
-            Q(model_type__iexact=value) | Q(model_type__isnull=True) | Q(model_type='')
-        ).distinct()
+        return common.filters.filter_content_type(
+            queryset, 'model_type', value, allow_null=True
+        )
 
 
 class ParameterTemplateMixin:
@@ -839,12 +848,20 @@ class ParameterFilter(FilterSet):
         """Metaclass options for the filterset."""
 
         model = common.models.Parameter
-        fields = ['model_type', 'model_id', 'template', 'updated_by']
+        fields = ['model_id', 'template', 'updated_by']
 
     enabled = rest_filters.BooleanFilter(
         label='Template Enabled', field_name='template__enabled'
     )
 
+    model_type = rest_filters.CharFilter(method='filter_model_type', label='Model Type')
+
+    def filter_model_type(self, queryset, name, value):
+        """Filter queryset to include only Parameters of the given model type."""
+        return common.filters.filter_content_type(
+            queryset, 'model_type', value, allow_null=False
+        )
+
 
 class ParameterMixin:
     """Mixin class for Parameter views."""

src/backend/InvenTree/common/filters.py

@@ -0,0 +1,53 @@
+"""Custom API filters for InvenTree."""
+
+
+def filter_content_type(
+    queryset, field_name: str, content_type: str | int | None, allow_null: bool = True
+):
+    """Filter a queryset by content type.
+
+    Arguments:
+        queryset: The queryset to filter.
+        field_name: The name of the content type field within the current model context.
+        content_type: The content type to filter by (name or ID).
+        allow_null: If True, include entries with null content type.
+
+    Returns:
+        Filtered queryset.
+    """
+    if content_type is None:
+        return queryset
+
+    from django.contrib.contenttypes.models import ContentType
+    from django.db.models import Q
+
+    ct = None
+
+    # First, try to resolve the content type via a PK value
+    try:
+        content_type_id = int(content_type)
+        ct = ContentType.objects.get_for_id(content_type_id)
+    except (ValueError, ContentType.DoesNotExist):
+        ct = None
+
+    if len(content_type.split('.')) == 2:
+        # Next, try to resolve the content type via app_label.model_name
+        try:
+            app_label, model = content_type.split('.')
+            ct = ContentType.objects.get(app_label=app_label, model=model)
+        except ContentType.DoesNotExist:
+            ct = None
+
+    else:
+        # Next, try to resolve the content type via a model name
+        ct = ContentType.objects.filter(model__iexact=content_type).first()
+
+    if ct is None:
+        raise ValueError(f'Invalid content type: {content_type}')
+
+    q = Q(**{f'{field_name}': ct})
+
+    if allow_null:
+        q |= Q(**{f'{field_name}__isnull': True})
+
+    return queryset.filter(q)

src/backend/InvenTree/common/models.py

@@ -2643,9 +2643,7 @@ class Parameter(
         """Check if the user has the required permission for this parameter."""
         from InvenTree.models import InvenTreeParameterMixin
 
-        model_class = common.validators.parameter_model_class_from_label(
-            self.model_type
-        )
+        model_class = self.model_type.model_class()
 
         if not issubclass(model_class, InvenTreeParameterMixin):
             raise ValidationError(_('Invalid model type specified for parameter'))

src/backend/InvenTree/common/serializers.py

@@ -772,9 +772,7 @@ class ParameterSerializer(
         # Ensure that the user has permission to modify parameters for the specified model
         user = self.context.get('request').user
 
-        target_model_class = common.validators.parameter_model_class_from_label(
-            model_type
-        )
+        target_model_class = model_type.model_class()
 
         if not issubclass(target_model_class, InvenTreeParameterMixin):
             raise PermissionDenied(_('Invalid model type specified for parameter'))

src/frontend/src/tables/general/ParameterTable.tsx

@@ -161,6 +161,9 @@ export function ParameterTable({
     url: ApiEndpoints.parameter_list,
     title: t`Add Parameter`,
     fields: useParameterFields({ modelType, modelId }),
+    initialData: {
+      data: ''
+    },
     table: table
   });