Allow wtforms to use localized strings

While this is not a solution for #59, it is a necessary first step
to address it properly. Please see the discussion in #59 why this
is not a sufficient fix.

Another shortcoming here is that we should probably forward *all*
languages accepted by the user agent to the form to provide the
best degration we can if the primary language picked by the user
is not offered by wtforms.

snikket_web/admin.py

@@ -19,12 +19,11 @@
     abort,
     flash,
 )
-import flask_wtf
 
 from flask_babel import lazy_gettext as _l, _
 
 from . import prosodyclient
-from .infra import client, circle_name
+from .infra import client, circle_name, BaseForm
 
 bp = Blueprint("admin", __name__, url_prefix="/admin")
 
@@ -35,7 +34,7 @@ async def index() -> str:
     return await render_template("admin_home.html")
 
 
-class PasswordResetLinkPost(flask_wtf.FlaskForm):  # type: ignore
+class PasswordResetLinkPost(BaseForm):
     action_create = wtforms.StringField()
     action_revoke = wtforms.StringField()
 
@@ -55,7 +54,7 @@ async def users() -> str:
     )
 
 
-class DeleteUserForm(flask_wtf.FlaskForm):  # type:ignore
+class DeleteUserForm(BaseForm):
     action_delete = wtforms.SubmitField(
         _l("Delete user permanently")
     )
@@ -132,11 +131,11 @@ async def create_password_reset_link() -> typing.Union[str, quart.Response]:
     )
 
 
-class InvitesListForm(flask_wtf.FlaskForm):  # type:ignore
+class InvitesListForm(BaseForm):
     action_revoke = wtforms.StringField()
 
 
-class InvitePost(flask_wtf.FlaskForm):  # type:ignore
+class InvitePost(BaseForm):
     circles = wtforms.SelectMultipleField(
         _l("Invite to circle"),
         # NOTE: This is for when/if we ever support multi-group invites.
@@ -230,7 +229,7 @@ async def invitations() -> typing.Union[str, quart.Response]:
     )
 
 
-class InviteForm(flask_wtf.FlaskForm):  # type:ignore
+class InviteForm(BaseForm):
     action_revoke = wtforms.SubmitField(
         _l("Revoke")
     )
@@ -302,7 +301,7 @@ async def edit_invite(id_: str) -> typing.Union[str, quart.Response]:
     )
 
 
-class CirclePost(flask_wtf.FlaskForm):  # type:ignore
+class CirclePost(BaseForm):
     name = wtforms.StringField(
         _l("Name"),
         validators=[wtforms.validators.InputRequired()],
@@ -350,7 +349,7 @@ async def create_circle() -> typing.Union[str, quart.Response]:
     )
 
 
-class EditCircleForm(flask_wtf.FlaskForm):  # type:ignore
+class EditCircleForm(BaseForm):
     name = wtforms.StringField(
         _l("Name"),
         validators=[wtforms.validators.InputRequired()],

snikket_web/infra.py

@@ -10,6 +10,7 @@
 )
 
 import flask_babel
+import flask_wtf
 from flask_babel import _
 
 from . import prosodyclient
@@ -55,3 +56,14 @@ def generate_error_id() -> str:
     return base64.b32encode(secrets.token_bytes(8)).decode(
         "ascii"
     ).rstrip("=")
+
+
+class BaseForm(flask_wtf.FlaskForm):  # type:ignore
+    def __init__(self, *args: typing.Any, **kwargs: typing.Any):
+        meta = kwargs["meta"] = dict(kwargs.get("meta", {}))
+        if "locales" not in meta:
+            locale = flask_babel.get_locale()
+            if locale:
+                meta["locales"] = [str(locale)]
+
+        super().__init__(*args, **kwargs)

snikket_web/invite.py

@@ -16,10 +16,9 @@
 
 import wtforms
 
-import flask_wtf
 from flask_babel import lazy_gettext as _l
 
-from .infra import client, selected_locale
+from .infra import client, selected_locale, BaseForm
 
 
 bp = Blueprint("invite", __name__)
@@ -101,7 +100,7 @@ async def view(id_: str) -> typing.Union[quart.Response,
     )
 
 
-class RegisterForm(flask_wtf.FlaskForm):  # type:ignore
+class RegisterForm(BaseForm):
     localpart = wtforms.StringField(
         _l("Username"),
     )
@@ -172,7 +171,7 @@ async def register(id_: str) -> typing.Union[str, quart.Response]:
     )
 
 
-class ResetForm(flask_wtf.FlaskForm):  # type:ignore
+class ResetForm(BaseForm):
     password = wtforms.PasswordField(
         _l("Password"),
     )

snikket_web/main.py

@@ -22,17 +22,16 @@
 import wtforms
 
 import flask_wtf
-
 from flask_babel import lazy_gettext as _l, _
 
 from . import xmpputil, _version
-from .infra import client
+from .infra import client, BaseForm
 
 
 bp = quart.Blueprint("main", __name__)
 
 
-class LoginForm(flask_wtf.FlaskForm):  # type:ignore
+class LoginForm(BaseForm):
     address = wtforms.TextField(
         _l("Address"),
         validators=[wtforms.validators.InputRequired()],