What is the correct way to populate select choices from session data?

Question

I\'m storing some variables in the session when the user logs in, to use later to populate a field.

from flask_wtf import Form
from wtforms import SelectFiel         


        

Answer 1

Code in a class definition is executed at import time, not when the class is instantiated. You need to move the access to session to the __init__ method so that it will be accessed when creating a form in a view function.

class Institution(Form):
    organization = SelectField()

    def __init__(self, *args, **kwargs):
        self.organization.kwargs['choices'] = [(x, x) for x in session.get('city', ('not set',))]
        super().__init__(*args, **kwargs)

This applies to anything that needs an application or request context, such as a database query, not just the session.