Flask url_for gives error when routing in modular application

Question

I am building a modular application in Flask, and i keep getting a build error if i refer to a function in another Blueprint from my current Blueprint e.g I have a file userProfiles.py

@userP.route('/myProfile/', methods=['GET']) 
def showProfile():
     .....

An in another file userAccounts.py i have

@userA.route('/login/', methods=['GET', 'POST'])
def login():
     .....

And then i have a main.py that registers all the blueprints and does app.run()

now i am trying to do url_for('userA.login) from my showProfile function but i keep getting a - werkzeug.routing.BuildError - . I haven't been able to solve this and non of the solutions online have helped me.

P.S. The url_for function does not work in my templates either, for some reason it just doesn't pick up the functions, i had no choice but to href to the path.

Just to add a tad bit more information i don't hav duplicate functions at all, all the functions and their names are unique and the url_for routing works fine within each Blueprint

Here is the Traceback:

Traceback (most recent call last):
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1701, in __call__
    return self.wsgi_app(environ, start_response)
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1689, in wsgi_app
    response = self.make_response(self.handle_exception(e))
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1687, in wsgi_app
    response = self.full_dispatch_request()
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1360, in full_dispatch_request
    rv = self.handle_user_exception(e)
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1358, in full_dispatch_request
    rv = self.dispatch_request()
  File "/usr/local/lib/python2.7/dist-packages/flask/app.py", line 1344, in dispatch_request
    return self.view_functions[rule.endpoint](**req.view_args)
  File "/home/cevdet/PycharmProjects/FlaskProjects/jobperfect/userProfiles.py", line 126, in showProfile
    else: return redirect(url_for('userA.login'))
  File "/usr/local/lib/python2.7/dist-packages/flask/helpers.py", line 361, in url_for
    return appctx.app.handle_url_build_error(error, endpoint, values)
  File "/usr/local/lib/python2.7/dist-packages/flask/helpers.py", line 354, in url_for
    force_external=external)
  File "/usr/local/lib/python2.7/dist-packages/werkzeug/routing.py", line 1607, in build
    raise BuildError(endpoint, values, method)
BuildError: ('userA.login', {}, None)
127.0.0.1 - - [17/Sep/2012 23:55:12] "GET /myP

Answer 1

How did you declared your blueprint userA?

When you using url_for() with blueprints, the prefix of endpoint string(as blueprint identifier) must be name of blueprint as you passed for first argument, not variable name that the blueprint has assigned to.

subapp = Blueprint('profile', __name__)

@subapp.route('/<username>')
def fetch_profile(username):
    pass

If you declared blueprint like above, you should call url_for() like below:

url_for('profile.fetch_profile', username=arg)