Routes and URL Rules
Routing is how Flask maps URLs to your Python functions. The @app.route() decorator is the primary way to define these mappings:
@app.route("/")
def index():
return "Home page"
@app.route("/about")
def about():
return "About page"You can bind multiple URLs to the same function. This is handy when you want the same content accessible from different paths:
@app.route("/home")
@app.route("/")
def index():
return "Welcome!"By default, Flask adds a trailing slash automatically. If you visit /about without the slash, it redirects to /about/. You can disable this with strict_slashes=False:
@app.route("/about", strict_slashes=False)
def about():
return "About"Flask supports several URL converters for dynamic segments. These let you constrain what values are acceptable:
@app.route("/user/") # string (default)
@app.route("/post/") # integer
@app.route("/price/") # float
@app.route("/filepath/") # path (allows slashes)
@app.route("/uuid/") # UUID If two routes could match the same URL, Flask picks the most specific one. For example, /post/123 matches /post/ before /post/ because the int converter is more specific.
Every route has an endpoint name — by default it's the function name. You can override it if needed:
@app.route("/profile", endpoint="user_profile")
def profile():
return "Your profile"Endpoint names matter when you use url_for() to generate URLs dynamically, which is the recommended approach over hardcoding paths.