fix: Add user filtering to changed_by. Fixes #27986 (#29287)

Co-authored-by: Markus Eriksson <markus.eriksson@sinch.com>

superset/css_templates/api.py

@@ -35,7 +35,12 @@ from superset.css_templates.schemas import (
 )
 from superset.extensions import event_logger
 from superset.models.core import CssTemplate
-from superset.views.base_api import BaseSupersetModelRestApi, statsd_metrics
+from superset.views.base_api import (
+    BaseSupersetModelRestApi,
+    RelatedFieldFilter,
+    statsd_metrics,
+)
+from superset.views.filters import BaseFilterRelatedUsers, FilterRelatedOwners
 
 logger = logging.getLogger(__name__)
 
@@ -91,6 +96,13 @@ class CssTemplateRestApi(BaseSupersetModelRestApi):
     openapi_spec_tag = "CSS Templates"
     openapi_spec_methods = openapi_spec_methods_override
 
+    related_field_filters = {
+        "changed_by": RelatedFieldFilter("first_name", FilterRelatedOwners),
+    }
+    base_related_field_filters = {
+        "changed_by": [["id", BaseFilterRelatedUsers, lambda: []]],
+    }
+
     @expose("/", methods=("DELETE",))
     @protect()
     @safe