Mastering Flask Web Development - Second Edition

The url_for() function

The url_for function returns the URL of a route by giving the route function name as a parameter, as shown in the following code. This allows URLs to be changed without worrying about where links will break:

{{ url_for('home') }} 
/ 

Here, home is the name of a function that is registered as an endpoint on Flask, and the relative URL root associated with it, so on our main.py, we must define a function to deal with the HTTP request and register it on Flask using the decorator app.route(rule, **options), as shown in the following code:

@app.route('/')def home():...

If we had a route that had positional arguments in the URL, we pass them as kwargs. They will be filled in for us in the resultant URL as follows:

{{ url_for('post', ...