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Can Flask have optional URL parameters?

Posted by: admin November 1, 2017 Leave a comment

Questions:

Is it possible to directly declare a flask URL optional parameter?

Currently I’m proceeding the following way:

@user.route('/<userId>')
@user.route('/<userId>/<username>')
def show(userId, username=None):
    .................

Is there anything that can allow me to directly say that “username” is optional?

Answers:

Another way is to write

@user.route('/<user_id>', defaults={'username': None})
@user.route('/<user_id>/<username>')
def show(user_id, username):
    pass

But I guess that you want to write a single route and mark username as optional? If that’s the case, I don’t think it’s possible.

Questions:
Answers:

Almost the same as Audrius cooked up some months ago, but you might find it a bit more readable with the defaults in the function head – the way you are used to with python:

@app.route('/<user_id>')
@app.route('/<user_id>/<username>')
def show(user_id, username='Anonymous'):
    return user_id + ':' + username

Questions:
Answers:

If you are using Flask-Restful like me, it is also possible this way:

api.add_resource(UserAPI, '/<userId>', '/<userId>/<username>', endpoint = 'user')

a then in your Resource class:

class UserAPI(Resource):

  def get(self, userId, username=None):
    pass

Questions:
Answers:
@app.route('/', defaults={'path': ''})
@app.route('/< path:path >')
def catch_all(path):
    return 'You want path: %s' % path

http://flask.pocoo.org/snippets/57/

Questions:
Answers:
@user.route('/<userId>/')  # NEED '/' AFTER LINK
@user.route('/<userId>/<username>')
def show(userId, username=None):
    pass

http://flask.pocoo.org/docs/0.10/quickstart/#routing

Questions:
Answers:
@user.route('/<user_id>', defaults={'username': default_value})
@user.route('/<user_id>/<username>')
def show(user_id, username):
   #
   pass

Questions:
Answers:

You can write as you show in example, but than you get build-error.

For fix this:

  1. print app.url_map () in you root .py
  2. you see something like:

<Rule '/<userId>/<username>' (HEAD, POST, OPTIONS, GET) -> user.show_0>

and

<Rule '/<userId>' (HEAD, POST, OPTIONS, GET) -> .show_1>

  1. than in template you can {{ url_for('.show_0', args) }} and {{ url_for('.show_1', args) }}
Questions:
Answers:

I think you can use Blueprint and that’s will make ur code look better and neatly.

example:

from flask import Blueprint

bp = Blueprint(__name__, "example")

@bp.route("/example", methods=["POST"])
def example(self):
   print("example")

Questions:
Answers:

Since Flask 0.10 you can`t add multiple routes to one endpoint. But you can add fake endpoint

@user.route('/<userId>')
def show(userId):
   return show_with_username(userId)

@user.route('/<userId>/<username>')
def show_with_username(userId,username=None):
   pass