string_validation: Factor out stream name validation.

Co-authored-by: Shlok Patel <shlokcpatel2001@gmail.com>

zerver/lib/actions.py

@@ -148,7 +148,6 @@ from zerver.lib.streams import (
     access_stream_for_send_message,
     can_access_stream_user_ids,
     check_stream_access_based_on_stream_post_policy,
-    check_stream_name,
     create_stream_if_needed,
     get_default_value_for_history_public_to_subscribers,
     get_web_public_streams_queryset,
@@ -156,6 +155,7 @@ from zerver.lib.streams import (
     send_stream_creation_event,
     subscribed_to_stream,
 )
+from zerver.lib.string_validation import check_stream_name
 from zerver.lib.timestamp import datetime_to_timestamp, timestamp_to_datetime
 from zerver.lib.timezone import canonicalize_timezone
 from zerver.lib.topic import (

zerver/lib/streams.py

@@ -13,6 +13,7 @@ from zerver.lib.exceptions import (
 )
 from zerver.lib.markdown import markdown_convert
 from zerver.lib.stream_subscription import get_active_subscriptions_for_stream_id
+from zerver.lib.string_validation import check_stream_name
 from zerver.models import (
     DefaultStreamGroup,
     Realm,
@@ -175,20 +176,6 @@ def create_streams_if_needed(
     return added_streams, existing_streams
 
 
-def check_stream_name(stream_name: str) -> None:
-    if stream_name.strip() == "":
-        raise JsonableError(_("Invalid stream name '{}'").format(stream_name))
-    if len(stream_name) > Stream.MAX_NAME_LENGTH:
-        raise JsonableError(
-            _("Stream name too long (limit: {} characters).").format(Stream.MAX_NAME_LENGTH)
-        )
-    for i in stream_name:
-        if ord(i) == 0:
-            raise JsonableError(
-                _("Stream name '{}' contains NULL (0x00) characters.").format(stream_name)
-            )
-
-
 def subscribed_to_stream(user_profile: UserProfile, stream_id: int) -> bool:
     return Subscription.objects.filter(
         user_profile=user_profile,

zerver/lib/string_validation.py

@@ -0,0 +1,20 @@
+from typing import Optional
+
+from django.utils.translation import gettext as _
+
+from zerver.lib.exceptions import JsonableError
+from zerver.models import Stream
+
+
+def check_stream_name(stream_name: str) -> None:
+    if stream_name.strip() == "":
+        raise JsonableError(_("Invalid stream name '{}'").format(stream_name))
+    if len(stream_name) > Stream.MAX_NAME_LENGTH:
+        raise JsonableError(
+            _("Stream name too long (limit: {} characters).").format(Stream.MAX_NAME_LENGTH)
+        )
+    for i in stream_name:
+        if ord(i) == 0:
+            raise JsonableError(
+                _("Stream name '{}' contains NULL (0x00) characters.").format(stream_name)
+            )

zerver/views/streams.py

@@ -61,11 +61,11 @@ from zerver.lib.streams import (
     access_stream_by_name,
     access_stream_for_delete_or_update,
     access_web_public_stream,
-    check_stream_name,
     check_stream_name_available,
     filter_stream_authorization,
     list_to_streams,
 )
+from zerver.lib.string_validation import check_stream_name
 from zerver.lib.topic import (
     get_topic_history_for_public_stream,
     get_topic_history_for_stream,