Flask-Babel convert Flask-WTF SelectField - flask

Question

I want to convert Flask-WTF SelectField value with Flask-Babel.
Here is the snippet of my code:
from flask_babel import _, lazy_gettext as _l
class PaymentStatus(enum.Enum):
REJECTED = 'REJECTED'
COMPLETED = 'COMPLETED'
EXPIRED = 'EXPIRED'
def __str__(self):
return self.value
payment_status = [(str(y), y) for y in (PaymentStatus)]
def course_list():
return Course.query.all()
class PaymentForm(FlaskForm):
course_name = QuerySelectField(_l('Course name'), validators=[required()], query_factory=course_list)
status_of_payment = SelectField(_l('Payment Status'), choices=payment_status)
# ...
# ...
There, I want to localization the SelectField choices value and QuerySelectField query_factory value with Flask-Babel.
Is it possible..?, if so, any example or refer tutorial would be appreciated :)

Answer 1

The SelectField choices could be handled by lazy_gettext().
Quote from The Flask Mega-Tutorial Part XIII: I18n and L10n
Some string literals are assigned outside of a request, usually when the application is starting up, so at the time these texts are evaluated there is no way to know what language to use.
Flask-Babel provides a lazy evaluation version of _() that is called lazy_gettext().
from flask_babel import lazy_gettext as _l
class LoginForm(FlaskForm):
username = StringField(_l('Username'), validators=[DataRequired()])
# ...
For choices
from flask_babel import _, lazy_gettext as _l
class PaymentStatus(enum.Enum):
REJECTED = _l('REJECTED')
COMPLETED = _l('COMPLETED')
EXPIRED = _l('EXPIRED')
def __str__(self):
return self.value
QuerySelectField query_factory accepts values queried from the database. These values should not be handled by Flask-Babel/babel. Cause the database stores data outside the Python source code.
Possible solutions:
Add a translation field in the database table and update the translation manually. Or
Using a Third-Party Translation Service on the webpage and handle it by AJAX
BTW, The Flask Mega-Tutorial made by Miguel Grinberg is a very famous Flask tutorial. All these situations are included in it.