Create dynamic URLs in Flask with url_for()

Refer to the Flask API document for flask.url_for()

Other sample snippets of usage for linking js or css to your template are below.

<script src="{{ url_for('static', filename='jquery.min.js') }}"></script>

<link rel=stylesheet type=text/css href="{{ url_for('static', filename='style.css') }}">

It takes keyword arguments for the variables:

url_for('add', variable=foo)
url_for('remove', variable=foo)

The flask-server would have functions:

@app.route('/<variable>/add', methods=['GET', 'POST'])
def add(variable):

@app.route('/<variable>/remove', methods=['GET', 'POST'])
def remove(variable):

url_for in Flask is used for creating a URL to prevent the overhead of having to change URLs throughout an application (including in templates). Without url_for, if there is a change in the root URL of your app then you have to change it in every page where the link is present.

Syntax: url_for('name of the function of the route','parameters (if required)')

It can be used as:

@app.route('/index')
@app.route('/')
def index():
    return 'you are in the index page'

Now if you have a link the index page:you can use this:

<a href={{ url_for('index') }}>Index</a>

You can do a lot o stuff with it, for example:

@app.route('/questions/<int:question_id>'):    #int has been used as a filter that only integer will be passed in the url otherwise it will give a 404 error
def find_question(question_id):  
    return ('you asked for question{0}'.format(question_id))

For the above we can use:

<a href = {{ url_for('find_question' ,question_id=1) }}>Question 1</a>

Like this you can simply pass the parameters!