สร้าง URL ด้วย url_for

Typing "/user/alice" by hand breaks the day you rename a route. Flask offers url_for to build links from your view names instead.

url_for takes the view function name and returns its path. Change the route string later and every generated link updates automatically. 🔗

By default the endpoint is the view function's name, not its URL path. So def home() is referenced as url_for('home').

For routes with captured parts, supply them as keyword arguments. url_for drops each value into the matching angle-bracket slot.

Arguments that do not fit a route slot are added as a query string. So passing page=2 appends ?page=2 to the generated URL.

Templates call url_for too, so your HTML links never go stale. It is the standard way to write hrefs in Jinja2 pages.

Because links derive from endpoint names, you can rename a URL path freely. Every url_for call keeps working, so refactors stay safe.

Combine url_for with redirect to send users to a named view. You get a clean, refactor-proof redirect without writing the path by hand.

Pass _external=True to get a full http://host/path link. This is handy for emails or anywhere a relative path will not do.

url_for also builds links to assets via the static endpoint. That keeps CSS and image paths correct even if your app mounts elsewhere.

Make url_for your default for every internal link. Hardcoded strings creep in and rot; generated URLs stay correct as your app evolves.

You call url_for('profile', name='alice', page=2). Where does page=2 end up?

url_for turns endpoint names into paths, fills route variables, and tacks extras onto the query string. Next: trailing slashes. 🧩