Flash messages in Ruby on Rails - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a flash message in Rails?

A flash message is a way to send a one-time message from the controller to the view, usually to show notices or alerts after an action like form submission.

beginner

How long does a flash message last in Rails?

Flash messages last for exactly one request cycle. They appear on the next page load and then disappear automatically.

beginner

How do you set a flash message in a Rails controller?

You set a flash message by assigning a string to flash[:key], for example: flash[:notice] = "Saved successfully".

intermediate

What is the difference between flash and flash.now in Rails?

flash sets a message for the next request, while flash.now sets a message for the current request only, useful when rendering instead of redirecting.

beginner

Where in a Rails view do you usually display flash messages?

Flash messages are usually displayed in the application layout or a shared partial, so they appear on any page after an action.

What does flash[:alert] typically represent in Rails?

A A permanent message

B A success message

C A debug message

D An error or warning message

flash[:alert] is conventionally used to show error or warning messages to the user.

Which method shows a flash message immediately without redirecting?

A flash.now

B flash.next

C flash.show

D flash.set

flash.now sets a flash message for the current request, so it appears immediately when rendering.

Where should you place flash message display code in a Rails app?

A In the application layout or a shared partial

B Only in the controller

C In the database

D In the model

Flash messages are shown in views, usually in the main layout or a shared partial for consistency.

What happens to a flash message after it is displayed once?

A It repeats twice

B It stays forever

C It is cleared automatically

D It moves to the database

Flash messages are designed to last only one request cycle and then clear automatically.

How do you set a success flash message in Rails?

A flash[:error] = "Success!"

B flash[:notice] = "Success!"

C flash[:alert] = "Success!"

D flash[:fail] = "Success!"

flash[:notice] is commonly used for success or informational messages.

Explain how flash messages work in Rails and how you would use them in a simple form submission.

Think about how you tell a user their form was saved or had errors.

Describe the difference between flash and flash.now and when you would use each.

Consider what happens when you redirect versus render in Rails.