i18n: Deal with lazy strings more carefully.

This uses a more specific type `_StrPromise` to replace `Promise`
providing typing information for lazy translation strings.

In places where the callee evaluates the `_StrPromise` object in all
cases we simply force the evaluation with `str()`. This includes
`JsonableError` that ends up handled by the error handler middleware,
and `internal_send_stream_message` that depends on `check_stream_topic`,
requiring the `topic` to be evaluated anyway. In other siuations, the
callee is expected to be able to handle `StrPromise` explicitly.

Signed-off-by: Zixuan James Li <p359101898@gmail.com>

zerver/actions/message_edit.py

@@ -1,5 +1,5 @@
 import datetime
-from typing import Any, Dict, Iterable, List, Optional, Set, TypedDict
+from typing import TYPE_CHECKING, Any, Dict, Iterable, List, Optional, Set, TypedDict
 
 from django.conf import settings
 from django.db import transaction
@@ -66,6 +66,9 @@ from zerver.models import (
 )
 from zerver.tornado.django_api import send_event
 
+if TYPE_CHECKING:
+    from django.utils.functional import _StrPromise as StrPromise
+
 
 def subscriber_info(user_id: int) -> Dict[str, Any]:
     return {"id": user_id, "flags": ["read"]}
@@ -198,10 +201,10 @@ def send_message_moved_breadcrumbs(
     user_profile: UserProfile,
     old_stream: Stream,
     old_topic: str,
-    old_thread_notification_string: Optional[str],
+    old_thread_notification_string: Optional["StrPromise"],
     new_stream: Stream,
     new_topic: Optional[str],
-    new_thread_notification_string: Optional[str],
+    new_thread_notification_string: Optional["StrPromise"],
     changed_messages_count: int,
 ) -> None:
     # Since moving content between streams is highly disruptive,

zerver/actions/streams.py

@@ -844,7 +844,7 @@ def send_change_stream_permission_notification(
             new_policy=new_policy_name,
         )
         internal_send_stream_message(
-            sender, stream, Realm.STREAM_EVENTS_NOTIFICATION_TOPIC, notification_string
+            sender, stream, str(Realm.STREAM_EVENTS_NOTIFICATION_TOPIC), notification_string
         )
 
 
@@ -1030,7 +1030,7 @@ def send_change_stream_post_policy_notification(
             new_policy=Stream.POST_POLICIES[new_post_policy],
         )
         internal_send_stream_message(
-            sender, stream, Realm.STREAM_EVENTS_NOTIFICATION_TOPIC, notification_string
+            sender, stream, str(Realm.STREAM_EVENTS_NOTIFICATION_TOPIC), notification_string
         )
 
 
@@ -1153,7 +1153,7 @@ def do_rename_stream(stream: Stream, new_name: str, user_profile: UserProfile) -
         internal_send_stream_message(
             sender,
             stream,
-            Realm.STREAM_EVENTS_NOTIFICATION_TOPIC,
+            str(Realm.STREAM_EVENTS_NOTIFICATION_TOPIC),
             _("{user_name} renamed stream {old_stream_name} to {new_stream_name}.").format(
                 user_name=silent_mention_syntax_for_user(user_profile),
                 old_stream_name=f"**{old_name}**",
@@ -1190,7 +1190,7 @@ def send_change_stream_description_notification(
         )
 
         internal_send_stream_message(
-            sender, stream, Realm.STREAM_EVENTS_NOTIFICATION_TOPIC, notification_string
+            sender, stream, str(Realm.STREAM_EVENTS_NOTIFICATION_TOPIC), notification_string
         )
 
 
@@ -1276,7 +1276,7 @@ def send_change_stream_message_retention_days_notification(
             summary_line=summary_line,
         )
         internal_send_stream_message(
-            sender, stream, Realm.STREAM_EVENTS_NOTIFICATION_TOPIC, notification_string
+            sender, stream, str(Realm.STREAM_EVENTS_NOTIFICATION_TOPIC), notification_string
         )
 
 

zerver/forms.py

@@ -140,7 +140,7 @@ class RegistrationForm(forms.Form):
         if self.fields["password"].required and not check_password_strength(password):
             # The frontend code tries to stop the user from submitting the form with a weak password,
             # but if the user bypasses that protection, this error code path will run.
-            raise ValidationError(PASSWORD_TOO_WEAK_ERROR)
+            raise ValidationError(str(PASSWORD_TOO_WEAK_ERROR))
 
         return password
 
@@ -275,7 +275,7 @@ class LoggingSetPasswordForm(SetPasswordForm):
         if not check_password_strength(new_password):
             # The frontend code tries to stop the user from submitting the form with a weak password,
             # but if the user bypasses that protection, this error code path will run.
-            raise ValidationError(PASSWORD_TOO_WEAK_ERROR)
+            raise ValidationError(str(PASSWORD_TOO_WEAK_ERROR))
 
         return new_password
 

zerver/lib/hotspots.py

@@ -1,14 +1,16 @@
 # See https://zulip.readthedocs.io/en/latest/subsystems/hotspots.html
 # for documentation on this subsystem.
-from typing import Dict, List
+from typing import TYPE_CHECKING, Dict, List
 
 from django.conf import settings
-from django.utils.functional import Promise
 from django.utils.translation import gettext_lazy
 
 from zerver.models import UserHotspot, UserProfile
 
-INTRO_HOTSPOTS: Dict[str, Dict[str, Promise]] = {
+if TYPE_CHECKING:
+    from django.utils.functional import _StrPromise as StrPromise
+
+INTRO_HOTSPOTS: Dict[str, Dict[str, "StrPromise"]] = {
     "intro_streams": {
         "title": gettext_lazy("Catch up on a stream"),
         "description": gettext_lazy(
@@ -42,7 +44,7 @@ INTRO_HOTSPOTS: Dict[str, Dict[str, Promise]] = {
 # We would most likely implement new hotspots in the future that aren't
 # a part of the initial tutorial. To that end, classifying them into
 # categories which are aggregated in ALL_HOTSPOTS, seems like a good start.
-ALL_HOTSPOTS: Dict[str, Dict[str, Promise]] = {
+ALL_HOTSPOTS: Dict[str, Dict[str, "StrPromise"]] = {
     **INTRO_HOTSPOTS,
 }
 

zerver/lib/types.py

@@ -1,10 +1,23 @@
 import datetime
 from dataclasses import dataclass
-from typing import Any, Callable, Dict, List, Optional, Tuple, TypedDict, TypeVar, Union
+from typing import (
+    TYPE_CHECKING,
+    Any,
+    Callable,
+    Dict,
+    List,
+    Optional,
+    Tuple,
+    TypedDict,
+    TypeVar,
+    Union,
+)
 
-from django.utils.functional import Promise
 from typing_extensions import NotRequired
 
+if TYPE_CHECKING:
+    from django.utils.functional import _StrPromise as StrPromise
+
 # See zerver/lib/validator.py for more details of Validators,
 # including many examples
 ResultT = TypeVar("ResultT")
@@ -37,9 +50,11 @@ class ProfileDataElementUpdateDict(TypedDict):
 
 ProfileData = List[ProfileDataElement]
 
-FieldElement = Tuple[int, Promise, Validator[ProfileDataElementValue], Callable[[Any], Any], str]
-ExtendedFieldElement = Tuple[int, Promise, ExtendedValidator, Callable[[Any], Any], str]
-UserFieldElement = Tuple[int, Promise, RealmUserValidator, Callable[[Any], Any], str]
+FieldElement = Tuple[
+    int, "StrPromise", Validator[ProfileDataElementValue], Callable[[Any], Any], str
+]
+ExtendedFieldElement = Tuple[int, "StrPromise", ExtendedValidator, Callable[[Any], Any], str]
+UserFieldElement = Tuple[int, "StrPromise", RealmUserValidator, Callable[[Any], Any], str]
 
 ProfileFieldData = Dict[str, Union[Dict[str, str], str]]
 

zerver/models.py

@@ -907,7 +907,7 @@ class Realm(models.Model):
 
     def ensure_not_on_limited_plan(self) -> None:
         if self.plan_type == Realm.PLAN_TYPE_LIMITED:
-            raise JsonableError(self.UPGRADE_TEXT_STANDARD)
+            raise JsonableError(str(self.UPGRADE_TEXT_STANDARD))
 
     @property
     def subdomain(self) -> str:
@@ -1872,7 +1872,7 @@ class UserProfile(AbstractBaseUser, PermissionsMixin, UserBaseSettings):
     }
 
     def get_role_name(self) -> str:
-        return self.ROLE_ID_TO_NAME_MAP[self.role]
+        return str(self.ROLE_ID_TO_NAME_MAP[self.role])
 
     def profile_data(self) -> ProfileData:
         values = CustomProfileFieldValue.objects.filter(user_profile=self)
@@ -4505,7 +4505,9 @@ class CustomProfileField(models.Model):
     FIELD_CONVERTERS: Dict[int, Callable[[Any], Any]] = {
         item[0]: item[3] for item in ALL_FIELD_TYPES
     }
-    FIELD_TYPE_CHOICES: List[Tuple[int, Promise]] = [(item[0], item[1]) for item in ALL_FIELD_TYPES]
+    FIELD_TYPE_CHOICES: List[Tuple[int, "StrPromise"]] = [
+        (item[0], item[1]) for item in ALL_FIELD_TYPES
+    ]
 
     field_type: int = models.PositiveSmallIntegerField(
         choices=FIELD_TYPE_CHOICES,

zerver/views/streams.py

@@ -740,7 +740,7 @@ def send_messages_for_new_subscribers(
                     internal_prep_stream_message(
                         sender=sender,
                         stream=stream,
-                        topic=Realm.STREAM_EVENTS_NOTIFICATION_TOPIC,
+                        topic=str(Realm.STREAM_EVENTS_NOTIFICATION_TOPIC),
                         content=_(
                             "**{policy}** stream created by {user_name}. **Description:**"
                         ).format(

zerver/views/users.py

@@ -719,7 +719,7 @@ def create_user_backend(
         pass
 
     if not check_password_strength(password):
-        raise JsonableError(PASSWORD_TOO_WEAK_ERROR)
+        raise JsonableError(str(PASSWORD_TOO_WEAK_ERROR))
 
     target_user = do_create_user(
         email,