Refactor generation of additional lookup filters

netbox/netbox/filtersets.py

@@ -2,6 +2,7 @@ import django_filters
 from copy import deepcopy
 from django.contrib.contenttypes.models import ContentType
 from django.db import models
+from django_filters.exceptions import FieldLookupError
 from django_filters.utils import get_model_field, resolve_field
 
 from dcim.forms import MACAddressField
@@ -116,29 +117,18 @@ class BaseFilterSet(django_filters.FilterSet):
         return None
 
     @classmethod
-    def get_filters(cls):
-        """
-        Override filter generation to support dynamic lookup expressions for certain filter types.
-
-        For specific filter types, new filters are created based on defined lookup expressions in
-        the form `<field_name>__<lookup_expr>`
-        """
-        filters = super().get_filters()
-
+    def get_additional_lookups(cls, existing_filter_name, existing_filter):
         new_filters = {}
-        for existing_filter_name, existing_filter in filters.items():
-            # Loop over existing filters to extract metadata by which to create new filters
 
-            # If the filter makes use of a custom filter method or lookup expression skip it
-            # as we cannot sanely handle these cases in a generic mannor
+        # Skip nonstandard lookup expressions
         if existing_filter.method is not None or existing_filter.lookup_expr not in ['exact', 'in']:
-                continue
+            return {}
 
         # Choose the lookup expression map based on the filter type
         lookup_map = cls._get_filter_lookup_dict(existing_filter)
         if lookup_map is None:
             # Do not augment this filter type with more lookup expressions
-                continue
+            return {}
 
         # Get properties of the existing filter for later use
         field_name = existing_filter.field_name
@@ -146,11 +136,11 @@ class BaseFilterSet(django_filters.FilterSet):
 
         # Create new filters for each lookup expression in the map
         for lookup_name, lookup_expr in lookup_map.items():
-                new_filter_name = '{}__{}'.format(existing_filter_name, lookup_name)
+            new_filter_name = f'{existing_filter_name}__{lookup_name}'
 
             try:
                 if existing_filter_name in cls.declared_filters:
-                        # The filter field has been explicity defined on the filterset class so we must manually
+                    # The filter field has been explicitly defined on the filterset class so we must manually
                     # create the new filter with the same type because there is no guarantee the defined type
                     # is the same as the default type for the field
                     resolve_field(field, lookup_expr)  # Will raise FieldLookupError if the lookup is invalid
@@ -166,7 +156,7 @@ class BaseFilterSet(django_filters.FilterSet):
                     # The filter field is listed in Meta.fields so we can safely rely on default behaviour
                     # Will raise FieldLookupError if the lookup is invalid
                     new_filter = cls.filter_for_field(field, field_name, lookup_expr)
-                except django_filters.exceptions.FieldLookupError:
+            except FieldLookupError:
                 # The filter could not be created because the lookup expression is not supported on the field
                 continue
 
@@ -177,7 +167,24 @@ class BaseFilterSet(django_filters.FilterSet):
 
             new_filters[new_filter_name] = new_filter
 
-        filters.update(new_filters)
+        return new_filters
+
+    @classmethod
+    def get_filters(cls):
+        """
+        Override filter generation to support dynamic lookup expressions for certain filter types.
+
+        For specific filter types, new filters are created based on defined lookup expressions in
+        the form `<field_name>__<lookup_expr>`
+        """
+        filters = super().get_filters()
+
+        additional_filters = {}
+        for existing_filter_name, existing_filter in filters.items():
+            additional_filters.update(cls.get_additional_lookups(existing_filter_name, existing_filter))
+
+        filters.update(additional_filters)
+
         return filters
 
 
@@ -213,8 +220,12 @@ class PrimaryModelFilterSet(ChangeLoggedModelFilterSet):
         ).exclude(
             filter_logic=CustomFieldFilterLogicChoices.FILTER_DISABLED
         )
+
+        custom_field_filters = {}
         for cf in custom_fields:
-            self.filters['cf_{}'.format(cf.name)] = CustomFieldFilter(field_name=cf.name, custom_field=cf)
+            custom_field_filters[f'cf_{cf.name}'] = CustomFieldFilter(field_name=cf.name, custom_field=cf)
+
+        self.filters.update(custom_field_filters)
 
 
 class OrganizationalModelFilterSet(PrimaryModelFilterSet):