Flash messages for user feedback in Flask - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a flash message in Flask?

A flash message is a short message stored temporarily to show feedback to the user, like success or error notices, after a page reload or redirect.

beginner

How do you add a flash message in Flask?

Use the flash() function with a message string inside a route function, for example: flash('Profile updated successfully!').

beginner

How do you display flash messages in a Flask template?

Use a loop over get_flashed_messages() in your HTML template to show each message, often inside a styled alert box.

beginner

Why are flash messages useful in web apps?

They provide clear, temporary feedback to users about actions like form submissions, helping users understand what happened without extra clicks.

intermediate

What must you set in Flask to use flash messages securely?

You must set a secret key in your Flask app (e.g., app.secret_key = 'your_secret') to securely sign the session data used by flash messages.

Which Flask function is used to create a flash message?

A flash()

B message()

C notify()

D alert()

The flash() function is the built-in Flask method to create flash messages.

Where do flash messages get stored temporarily in Flask?

A In the session

B In the database

C In a cookie

D In a file

Flash messages are stored in the user's session, which requires a secret key.

How do you retrieve flash messages in a Flask template?

A Using fetch_messages()

B Using get_flashed_messages()

C Using show_flash()

D Using get_messages()

The get_flashed_messages() function returns all flash messages for display.

What must you set in your Flask app to enable flash messages?

A app.config['FLASH'] = True

B app.debug = True

C app.secret_key

D app.session_enabled = True

Setting app.secret_key is required to securely sign session data including flash messages.

Flash messages are best used for:

A Logging errors on the server

B Storing user preferences permanently

C Sending emails to users

D Temporary user feedback after actions

Flash messages provide temporary feedback to users, such as success or error notices.

Explain how to create and display a flash message in a Flask app.

Think about what you do in the Python code and what you do in the HTML template.

Why is setting a secret key important when using flash messages in Flask?

Consider how Flask keeps session data safe.