Route decorator (@app.route) in Flask - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is the purpose of the @app.route decorator in Flask?

The @app.route decorator tells Flask which URL should trigger a specific function. It connects a web address to the code that runs when that address is visited.

beginner

How do you define a route for the home page using @app.route?

You use @app.route('/') above a function. This means when someone visits the root URL (like 'http://localhost:5000/'), Flask runs that function.

intermediate

Can @app.route handle different HTTP methods? How?

Yes. You can add the methods argument like @app.route('/path', methods=['GET', 'POST']) to tell Flask which HTTP methods the route accepts.

intermediate

What happens if two functions have the same route with @app.route?

Flask will use the last function defined for that route, overwriting the previous one. This can cause unexpected behavior, so routes should be unique.

beginner

How can you capture a variable part of the URL using @app.route?

You use angle brackets in the route like @app.route('/user/<username>'). Flask passes the value in the URL to the function as an argument.

What does @app.route('/about') do in a Flask app?

A Imports the Flask module

B Creates a new Flask app

C Starts the Flask server

D Links the URL '/about' to a function that runs when visited

The route decorator connects the URL '/about' to a function that Flask runs when that URL is accessed.

How do you allow a route to accept both GET and POST requests?

A Add <code>methods=['GET', 'POST']</code> in <code>@app.route</code>

B Use <code>@app.methods(['GET', 'POST'])</code>

C Set <code>app.methods = ['GET', 'POST']</code>

D Flask routes accept all methods by default

You specify allowed HTTP methods by adding the methods argument in the route decorator.

What will Flask do if two functions have the same route?

A Throw an error and stop the app

B Use the last defined function for that route

C Run both functions in order

D Ignore the second function

Flask overwrites the first function with the last one defined for the same route.

How do you capture a username from the URL in Flask?

A Use <code>@app.route('/user/&lt;username&gt;')</code>

B Use <code>@app.route('/user/:username')</code>

C Use <code>@app.route('/user/username')</code>

D Use <code>@app.route('/user?username')</code>

Angle brackets in the route capture parts of the URL as variables passed to the function.

What URL does @app.route('/') represent?

A A 404 error page

B The about page

C The home or root page

D A static file

The '/' route is the root URL, usually the home page of the website.

Explain how the @app.route decorator works in Flask and how it connects URLs to functions.

Think about how you tell Flask what to do when someone visits a web page.

Describe how to create a dynamic route in Flask that accepts a username from the URL.

Imagine you want to greet different users by name in the URL.