Have topic_is_muted take a stream_id.

This function doesn't need a full Stream object to detect
whether a stream is muted, so we can save future callers
from doing unnecessary DB fetches.

zerver/lib/topic_mutes.py

@@ -78,11 +78,11 @@ def remove_topic_mute(user_profile, stream_id, topic_name):
     )
     row.delete()
 
-def topic_is_muted(user_profile, stream, topic_name):
-    # type: (UserProfile, Stream, Text) -> bool
+def topic_is_muted(user_profile, stream_id, topic_name):
+    # type: (UserProfile, int, Text) -> bool
     is_muted = MutedTopic.objects.filter(
         user_profile=user_profile,
-        stream_id=stream.id,
+        stream_id=stream_id,
         topic_name__iexact=topic_name,
     ).exists()
     return is_muted

zerver/tests/test_muting.py

@@ -28,8 +28,8 @@ class MutedTopicsTests(ZulipTestCase):
         self.assertIn([u'Verona', u'Verona3'], get_topic_mutes(user))
 
         stream = get_stream(u'Verona', user.realm)
-        self.assertTrue(topic_is_muted(user, stream, 'Verona3'))
-        self.assertTrue(topic_is_muted(user, stream, 'verona3'))
+        self.assertTrue(topic_is_muted(user, stream.id, 'Verona3'))
+        self.assertTrue(topic_is_muted(user, stream.id, 'verona3'))
 
     def test_remove_muted_topic(self):
         # type: () -> None

zerver/views/muting.py

@@ -18,7 +18,7 @@ def mute_topic(user_profile, stream_name, topic_name):
     # type: (UserProfile, str, str) -> HttpResponse
     (stream, recipient, sub) = access_stream_by_name(user_profile, stream_name)
 
-    if topic_is_muted(user_profile, stream, topic_name):
+    if topic_is_muted(user_profile, stream.id, topic_name):
         return json_error(_("Topic already muted"))
 
     do_mute_topic(user_profile, stream, recipient, topic_name)
@@ -29,7 +29,7 @@ def unmute_topic(user_profile, stream_name, topic_name):
     error = _("Topic is not there in the muted_topics list")
     stream = access_stream_for_unmute_topic(user_profile, stream_name, error)
 
-    if not topic_is_muted(user_profile, stream, topic_name):
+    if not topic_is_muted(user_profile, stream.id, topic_name):
         return json_error(error)
 
     do_unmute_topic(user_profile, stream, topic_name)