feat: Add an API to retrieve the count of tags applied to each object

openedx_tagging/core/tagging/rest_api/v1/urls.py

@@ -10,6 +10,7 @@
 router = DefaultRouter()
 router.register("taxonomies", views.TaxonomyView, basename="taxonomy")
 router.register("object_tags", views.ObjectTagView, basename="object_tag")
+router.register("object_tag_counts", views.ObjectTagCountsView, basename="object_tag_counts")
 
 urlpatterns = [
     path("", include(router.urls)),

openedx_tagging/core/tagging/rest_api/v1/views.py

@@ -26,7 +26,7 @@
 from ...data import TagDataQuerySet
 from ...import_export.api import export_tags
 from ...import_export.parsers import ParserFormat
-from ...models import Taxonomy
+from ...models import ObjectTag, Taxonomy
 from ...rules import ObjectTagPermissionItem
 from ..paginators import TAGS_THRESHOLD, DisabledTagsPagination, TagsPagination
 from .permissions import ObjectTagObjectPermissions, TagObjectPermissions, TaxonomyObjectPermissions
@@ -266,10 +266,6 @@ class ObjectTagView(
         * 400 - Invalid query parameter
         * 403 - Permission denied
 
-    **Create Query Returns**
-        * 403 - Permission denied
-        * 405 - Method not allowed
-
     **Update Parameters**
         * object_id (required): - The Object ID to add ObjectTags for.
 
@@ -411,6 +407,52 @@ def update(self, request, *args, **kwargs) -> Response:
         return self.retrieve(request, object_id)
 
 
+@view_auth_classes
+class ObjectTagCountsView(
+    mixins.RetrieveModelMixin,
+    GenericViewSet,
+):
+    """
+    View to retrieve the count of ObjectTags for all matching object IDs.
+
+    This API does NOT bother doing any permission checks as the "# of tags" is not considered sensitive information.
+
+    **Retrieve Parameters**
+        * object_id_pattern (required): - The Object ID to retrieve ObjectTags for. Can contain '*' at the end
+          for wildcard matching, or use ',' to separate multiple object IDs.
+
+    **Retrieve Example Requests**
+        GET api/tagging/v1/object_tag_counts/:object_id_pattern
+
+    **Retrieve Query Returns**
+        * 200 - Success
+    """
+
+    serializer_class = ObjectTagSerializer
+    lookup_field = "object_id_pattern"
+
+    def retrieve(self, request, *args, **kwargs) -> Response:
+        """
+        Retrieve the counts of object tags that belong to a given object_id pattern
+
+        Note: We override `retrieve` here instead of `list` because we are
+        passing in the Object ID (object_id) in the path (as opposed to passing
+        it in as a query_param) to retrieve the ObjectTag counts.
+        """
+        # This API does NOT bother doing any permission checks as the # of tags is not considered sensitive information.
+        object_id_pattern = self.kwargs["object_id_pattern"]
+        qs = ObjectTag.objects
+        if object_id_pattern.endswith("*"):
+            qs = qs.filter(object_id__startswith=object_id_pattern[0:len(object_id_pattern) - 1])
+        elif "*" in object_id_pattern:
+            raise ValidationError("Wildcard matches are only supported if the * is at the end.")
+        else:
+            qs = qs.filter(object_id__in=object_id_pattern.split(","))
+
+        qs = qs.values("object_id").annotate(num_tags=models.Count("id")).order_by("object_id")
+        return Response({row["object_id"]: row["num_tags"] for row in qs})
+
+
 @view_auth_classes
 class TaxonomyTagsView(ListAPIView, RetrieveUpdateDestroyAPIView):
     """

tests/openedx_tagging/core/tagging/test_views.py

@@ -32,6 +32,7 @@
 
 
 OBJECT_TAGS_RETRIEVE_URL = "/tagging/rest_api/v1/object_tags/{object_id}/"
+OBJECT_TAG_COUNTS_URL = "/tagging/rest_api/v1/object_tag_counts/{object_id_pattern}/"
 OBJECT_TAGS_UPDATE_URL = "/tagging/rest_api/v1/object_tags/{object_id}/?taxonomy={taxonomy_id}"
 
 LANGUAGE_TAXONOMY_ID = -1
@@ -916,6 +917,54 @@ def test_tag_object_count_limit(self):
             assert response.status_code == status.HTTP_400_BAD_REQUEST
 
 
+class TestObjectTagCountsViewSet(TestTagTaxonomyMixin, APITestCase):
+    """
+    Testing various cases for counting how many tags are applied to several objects.
+    """
+
+    def test_get_counts(self):
+        """
+        Test retrieving the counts of tags applied to various content objects.
+
+        This API does NOT bother doing any permission checks as the "# of tags" is not considered sensitive information.
+        """
+        # Course 2
+        api.tag_object(object_id="course02-unit01-problem01", taxonomy=self.free_text_taxonomy, tags=["other"])
+        # Course 7 Unit 1
+        api.tag_object(object_id="course07-unit01-problem01", taxonomy=self.free_text_taxonomy, tags=["a", "b", "c"])
+        api.tag_object(object_id="course07-unit01-problem02", taxonomy=self.free_text_taxonomy, tags=["a", "b"])
+        # Course 7 Unit 2
+        api.tag_object(object_id="course07-unit02-problem01", taxonomy=self.free_text_taxonomy, tags=["b"])
+        api.tag_object(object_id="course07-unit02-problem02", taxonomy=self.free_text_taxonomy, tags=["c", "d"])
+        api.tag_object(object_id="course07-unit02-problem03", taxonomy=self.free_text_taxonomy, tags=["N", "M", "x"])
+
+        def check(object_id_pattern: str):
+            result = self.client.get(OBJECT_TAG_COUNTS_URL.format(object_id_pattern=object_id_pattern))
+            assert result.status_code == status.HTTP_200_OK
+            return result.data
+
+        assert check(object_id_pattern="course02-*") == {
+            "course02-unit01-problem01": 1,
+        }
+        assert check(object_id_pattern="course07-unit01-*") == {
+            "course07-unit01-problem01": 3,
+            "course07-unit01-problem02": 2,
+        }
+        assert check(object_id_pattern="course07-unit*") == {
+            "course07-unit01-problem01": 3,
+            "course07-unit01-problem02": 2,
+            "course07-unit02-problem01": 1,
+            "course07-unit02-problem02": 2,
+            "course07-unit02-problem03": 3,
+        }
+        # Can also use a comma to separate explicit object IDs:
+        assert check(object_id_pattern="course07-unit01-problem01") == {"course07-unit01-problem01": 3}
+        assert check(object_id_pattern="course07-unit01-problem01,course07-unit02-problem02") == {
+            "course07-unit01-problem01": 3,
+            "course07-unit02-problem02": 2,
+        }
+
+
 class TestTaxonomyTagsView(TestTaxonomyViewMixin):
     """
     Tests the list/create/update/delete tags of taxonomy view