fix: only load counts once per request

cms/djangoapps/contentstore/xblock_storage_handlers/view_handlers.py

@@ -55,6 +55,7 @@
 from openedx.core.djangoapps.discussions.models import DiscussionsConfiguration
 from openedx.core.djangoapps.video_config.toggles import PUBLIC_VIDEO_SHARE
 from openedx.core.lib.gating import api as gating_api
+from openedx.core.lib.cache_utils import request_cached
 from openedx.core.toggles import ENTRANCE_EXAMS
 from xmodule.course_block import (
     DEFAULT_START_DATE,
@@ -1401,9 +1402,7 @@ def create_xblock_info(  # lint-amnesty, pylint: disable=too-many-statements
             # If the ENABLE_TAGGING_TAXONOMY_LIST_PAGE feature flag is enabled, we show the "Manage Tags" options
             if use_tagging_taxonomy_list_page():
                 xblock_info["use_tagging_taxonomy_list_page"] = True
-                # Create a pattern to match the IDs of the units, e.g. "block-v1:org+course+run+type@vertical+block@*"
-                unit_key_pattern = str(xblock.location.replace(block_type="vertical")).rsplit("@", 1)[0] + "@*"
-                xblock_info["tag_counts_by_unit"] = tagging_api.get_object_tag_counts(unit_key_pattern)
+                xblock_info["tag_counts_by_unit"] = _get_course_unit_tags(xblock.location.context_key)
 
             xblock_info[
                 "has_partition_group_components"
@@ -1418,6 +1417,19 @@ def create_xblock_info(  # lint-amnesty, pylint: disable=too-many-statements
     return xblock_info
 
 
+@request_cached()
+def _get_course_unit_tags(course_key) -> dict:
+    """
+    Get the count of tags that are applied to each unit (vertical) in this course, as a dict.
+    """
+    if not course_key.is_course:
+        return {}  # Unsupported key type, e.g. a library
+    # Create a pattern to match the IDs of the units, e.g. "block-v1:org+course+run+type@vertical+block@*"
+    vertical_key = course_key.make_usage_key('vertical', 'x')
+    unit_key_pattern = str(vertical_key).rsplit("@", 1)[0] + "@*"
+    return tagging_api.get_object_tag_counts(unit_key_pattern)
+
+
 def _was_xblock_ever_exam_linked_with_external(course, xblock):
     """
     Determine whether this XBlock is or was ever configured as an external proctored exam.