Can Flask Have Optional Url Parameters

Can Flask have optional URL parameters?

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.

Flask - Optional path args

Optional parameters are allowed in Flask.

You can define multiple rules for same function. Here is the documentation on URL Route Registrations.

Updated code:

import flask

win = flask.Flask(__name__)

@win.route('/<name>/', defaults={'ints': None, 'floats': None})
@win.route('/<name>/<int:ints>/', defaults={'floats': None})
@win.route("/<name>/<int:ints>/<float:floats>/")
def web(name, ints, floats):
    if ints!=None and floats!=None:
        return "Welcome Back: %s, Your Int: %d, Your Float: %f" % (name, ints, floats)
    elif ints!=None and floats==None:
        return "Welcome Back: %s, Your Int: %d" % (name, ints)
    return "Welcome Back: %s" % (name)

win.run(debug=True)

When chrome or any other web browser requests either of these URLs, Flask will invoke the associated function along with the arguments provided in the url. If no or less arguments are provided then default values of arguments will be used.

Screenshots:

Three parameters:

Two parameters:

One parameter:

Flask - Routing with multiple optional parameters

You can use filter in the URL instead of "sub-resources".
Then you can put search arguments in any order in your request:
/search?pg=<pg>&types=<types>

Inside the flask view function you can retrieve parameters from the request object:

@app.route('/search/')
def search():
    pg = request.args.get('pg')
    ...

Multiple optional parameters in flask-restful API?

Solved by using flask-resful's reqparse.

More info here: https://blog.miguelgrinberg.com/post/designing-a-restful-api-using-flask-restful

from flask import Flask
from flask_restful import Resource, Api
from flask_restful import reqparse

app = Flask(__name__)

api = Api(app)

class print_stuff(Resource):

    def __init__(self):
        self.reqparse = reqparse.RequestParser()
        self.reqparse.add_argument('name', type = str, default='')
        self.reqparse.add_argument('email', type = str, default='')
        self.reqparse.add_argument('address', type = str, default='')
        self.reqparse.add_argument('age', type = str, default='')
        super(hlr_lookup, self).__init__()

    def get(self):

        args = self.reqparse.parse_args()

        return {
            'your name is':args['name'],
            'your email is': args['email'],
            'your address is': args['address'],
            'your age is': args['age']
        }

api.add_resource(print_stuff,'/overflow_test')

if __name__ == '__main__':
    app.run(debug=True)

Now I can call the api like this:

127.0.0.1:5000/print_stuff?name=John&age=23&address=main street new york&email=something@gmail.com

Allow for multiple optional arguments in a Flask URL

In that case, just create simple route and access those variables in request.args like so:

@app.route('/test', methods=['GET'])
def test():
    arg1 = request.args.get('arg1', None)
    arg2 = request.args.get('arg2', None)
    if arg1:
        pass  # Do something with it
    elif arg2:
        pass  # Do something with it
    else:
        pass  # do something when no args given
    return jsonify()

And then in url you can pass like this:

/test
or
/test?arg2=321
or
/test?arg1=123
or
/test?arg1=123&arg2=321

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