perf: Extract Stream.get_client_data.

This function slims down the data that we get
from the database in order to create the
streams part of our client payload.

We also fix a typo.

We also clearly distinguish between queries
and lists here.

zerver/lib/actions.py

@@ -5421,7 +5421,7 @@ def get_occupied_streams(realm: Realm) -> QuerySet:
 
 def get_web_public_streams(realm: Realm) -> List[Dict[str, Any]]:
     query = Stream.objects.filter(realm=realm, deactivated=False, is_web_public=True)
-    streams = [(row.to_dict()) for row in query]
+    streams = Stream.get_client_data(query)
     return streams
 
 def do_get_streams(
@@ -5436,7 +5436,9 @@ def do_get_streams(
     # Start out with all streams in the realm with subscribers
     query = get_occupied_streams(user_profile.realm)
 
-    if not include_all_active:
+    if include_all_active:
+        streams = Stream.get_client_data(query)
+    else:
         # We construct a query as the or (|) of the various sources
         # this user requested streams from.
         query_filter = None  # type: Optional[Q]
@@ -5464,12 +5466,13 @@ def do_get_streams(
 
         if query_filter is not None:
             query = query.filter(query_filter)
+            streams = Stream.get_client_data(query)
         else:
-            # Don't bother doing to the database with no valid sources
-            query = []
+            # Don't bother going to the database with no valid sources
+            streams = []
 
-    streams = [(row.to_dict()) for row in query]
     streams.sort(key=lambda elt: elt["name"])
+
     if include_default:
         is_default = {}
         default_streams = get_default_streams_for_realm(user_profile.realm_id)

zerver/models.py

@@ -1432,7 +1432,7 @@ class Stream(models.Model):
     # * "email_token" is not realm-public and thus is not included here.
     # * is_in_zephyr_realm is a backend-only optimization.
     # * "deactivated" streams are filtered from the API entirely.
-    # * "realm" and "recipient" and not exposed to clients via the API.
+    # * "realm" and "recipient" are not exposed to clients via the API.
     # * "date_created" should probably be added here, as it's useful information
     #   to subscribers and is needed to compute is_old_stream.
     # * message_retention_days should be added here once the feature is
@@ -1449,7 +1449,11 @@ class Stream(models.Model):
         "first_message_id",
     ]
 
-    # This is stream information that is sent to clients
+    @staticmethod
+    def get_client_data(query: QuerySet) -> List[Dict[str, Any]]:
+        query = query.only(*Stream.API_FIELDS)
+        return [row.to_dict() for row in query]
+
     def to_dict(self) -> Dict[str, Any]:
         result = {}
         for field_name in self.API_FIELDS: