Partial templates in Ruby on Rails - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a partial template in Rails?

A partial template is a small reusable view file that helps you break down complex views into simpler pieces. It usually starts with an underscore (_) and can be included in other views.

beginner

How do you render a partial template in a Rails view?

You use the render method with the partial's name, like <%= render 'partial_name' %>. Rails looks for a file named _partial_name.html.erb.

intermediate

How can you pass local variables to a partial in Rails?

You pass a hash with locals option like <%= render 'partial_name', locals: { user: @user } %>. Inside the partial, you can use user directly.

beginner

Why use partial templates in Rails?

Partial templates help keep your code DRY (Don't Repeat Yourself), make views easier to read, and allow reuse of common UI parts like headers, footers, or forms.

beginner

What is the naming convention for partial templates in Rails?

Partial template files start with an underscore (_) followed by the name, for example, _form.html.erb. This tells Rails it is a partial and not a full view.

How do you include a partial named '_menu.html.erb' in a Rails view?

A <%= partial 'menu' %>

B <%= include 'menu' %>

C <%= render 'menu' %>

D <%= import 'menu' %>

Use render 'menu' to include the partial named '_menu.html.erb'.

What prefix does a Rails partial template file name have?

A No prefix

B Dot (.)

C Dash (-)

D Underscore (_)

Partial templates start with an underscore (_) to distinguish them from full views.

How do you pass a local variable named 'item' to a partial?

A <%= render 'partial', locals: { item: item } %>

B <%= render 'partial', item %>

C <%= render 'partial', with: item %>

D <%= render 'partial', locals: item %>

You pass locals as a hash: render 'partial', locals: { item: item }.

What is a main benefit of using partial templates?

A They speed up database queries

B They help reuse view code and keep it organized

C They replace controllers

D They automatically style your page

Partials help reuse and organize view code, making it cleaner and easier to maintain.

If you have a partial '_form.html.erb', how do you render it inside a view?

A Both A and C

B <%= render '_form' %>

C <%= render partial: 'form' %>

D <%= render 'form' %>

You can render a partial by render 'form' or render partial: 'form'.

Explain what a partial template is in Rails and why you would use it.

Think about breaking big views into smaller pieces.

Describe how to pass data to a partial template and how to access it inside the partial.

Passing variables is like giving a friend info to use in their part.