Before and after filters in Ruby on Rails - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a before filter in Rails controllers?

A before filter is a method that runs before a controller action. It can prepare data or check conditions before the main action runs.

beginner

What does an after filter do in Rails?

An after filter runs after a controller action finishes. It can be used to clean up, log information, or modify the response.

beginner

How do you declare a before filter in Rails 5 and later?

Use before_action :method_name inside the controller to run method_name before actions.

intermediate

Can you skip a before filter for some actions in Rails? How?

Yes, use skip_before_action :method_name, only: [:action1, :action2] to skip the filter for specific actions.

intermediate

Why use before and after filters instead of putting code directly in actions?

Filters help keep controller actions clean and focused. They let you reuse code like authentication or logging across many actions easily.

Which method runs before a Rails controller action?

A around_action

B after_action

C before_action

D skip_action

The before_action method runs a filter before the controller action.

How do you skip a before filter for only the 'show' action?

A skip_filter :filter_name, only: [:show]

B skip_after_action :filter_name, only: [:show]

C before_action :filter_name, except: [:show]

D skip_before_action :filter_name, only: [:show]

Use skip_before_action with only option to skip the filter for specific actions.

What is a common use for after filters?

A Logging or cleanup after an action

B Checking user permissions before an action

C Rendering views before an action

D Skipping actions

After filters often handle tasks like logging or cleanup after the main action.

Which Rails filter runs both before and after an action?

A around_action

B before_action

C after_action

D skip_action

around_action wraps the action, running code before and after it.

Why are filters useful in Rails controllers?

A They replace views

B They help reuse code and keep actions clean

C They speed up database queries

D They automatically generate routes

Filters let you run shared code like authentication before actions, keeping code organized.

Explain what before and after filters do in Rails controllers and give an example use case for each.

Think about what you want to do before or after a page loads.

How do you apply and skip a before filter for certain actions in a Rails controller?

Look at how to control which actions run the filter.