Public and assets folders in Ruby on Rails - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to serve static files from the public folder in Rails.

Ruby on Rails

Rails.application.config.serve_static_files = [1]

Drag options to blanks, or click blank then click option'

Atrue

Bnil

Cfalse

Dauto

Attempts:

3 left

💡 Hint

Common Mistakes

Using false disables serving static files.

Using nil or auto are not valid options here.

Setting serve_static_files to true tells Rails to serve files from the public folder.

2fill in blank

medium

Complete the code to add a CSS file named style.css to the asset pipeline in Rails.

Ruby on Rails

Rails.application.config.assets.precompile += %w([1])

Drag options to blanks, or click blank then click option'

Aimage.png

Bapplication.js

Cstyle.css

Dreset.scss

Attempts:

3 left

💡 Hint

Common Mistakes

Adding JavaScript or image files instead of CSS.

Using wrong file extensions.

Adding style.css to assets.precompile ensures it is included in the asset pipeline.

3fill in blank

hard

Fix the error in the code to correctly reference an image asset in a Rails view.

Ruby on Rails

<%= image_tag '[1]' %>

Drag options to blanks, or click blank then click option'

Alogo.png

Bassets/logo.png

C/assets/logo.png

Dpublic/logo.png

Attempts:

3 left

💡 Hint

Common Mistakes

Including folder paths like /assets/ or public/ causes errors.

Using incorrect file paths breaks image loading.

Use just the filename like logo.png with image_tag. Rails handles the asset path automatically.

4fill in blank

hard

Fill both blanks to create a hash that maps asset names to their digest paths in Rails.

Ruby on Rails

assets = { '[1]' => '[2]' } # maps logical name to digest path

Drag options to blanks, or click blank then click option'

Aapplication.css

Bapplication-123abc.css

Clogo.png

Dlogo-456def.png

Attempts:

3 left

💡 Hint

Common Mistakes

Swapping key and value.

Using non-digest filenames as values.

The logical asset name is application.css and the digest path includes a hash like application-123abc.css.

5fill in blank

hard

Fill all three blanks to write a Rails helper method that returns the full path for a given asset name.

Ruby on Rails

def asset_full_path(name)
  File.join(Rails.root, 'public', [1], [2] + name + [3])
end

Drag options to blanks, or click blank then click option'

Aassets

B/

C.

Dimages

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong folder names like 'images' instead of 'assets'.

Missing slashes or dots causing wrong paths.

This method joins the Rails root, public folder, assets folder, then adds a slash, the asset name, and a dot for extension.

Practice

1. What is the main purpose of the public folder in a Rails application?

easy

A. To store static files served directly without processing

B. To hold Ruby code files for controllers and models

C. To keep database migration files

D. To store files that Rails compiles before sending

Solution

1. Step 1: Understand the role of the public folder

   The public folder contains files like images, HTML, or JavaScript that Rails serves directly to the browser without any processing.

2. Step 2: Compare with other folders

   The assets folder is for files Rails processes (like compiling CSS or JavaScript), so it is not the public folder's role.

3. Final Answer:

   To store static files served directly without processing -> Option A

4. Quick Check:

   Public folder = static files served directly [OK]

Hint: Public folder serves files as-is, no processing needed [OK]

Common Mistakes:

• Confusing public with assets folder
• Thinking public holds Ruby code
• Assuming public processes files before serving

2. Which of the following is the correct path to place a CSS file that Rails will precompile and serve?

easy

A. app/public/stylesheets/style.css

B. public/assets/stylesheets/style.css

C. app/assets/stylesheets/style.css

D. config/assets/stylesheets/style.css

Solution

1. Step 1: Identify the standard assets folder for stylesheets

   Rails expects CSS files to be inside app/assets/stylesheets for precompilation and processing.

2. Step 2: Eliminate incorrect paths

   The public folder is for static files, not processed assets. The config folder does not hold assets.

3. Final Answer:

   app/assets/stylesheets/style.css -> Option C

4. Quick Check:

   CSS in assets/stylesheets = app/assets/stylesheets/style.css [OK]

Hint: Assets folder is inside app/, not public or config [OK]

Common Mistakes:

• Placing CSS directly in public folder
• Using wrong folder like config/assets
• Confusing assets with public folder paths

3. Given a file logo.png placed inside public/images, what URL path will serve this image in a Rails app?

medium

A. /assets/images/logo.png

B. /public/images/logo.png

C. /app/assets/images/logo.png

D. /images/logo.png

Solution

1. Step 1: Understand how public folder maps to URL

   Files inside public are served from the root URL path. So public/images/logo.png is accessible at /images/logo.png.

2. Step 2: Eliminate other options

   /assets/images/logo.png is for assets pipeline files, not public. /public/images/logo.png and /app/assets/images/logo.png are not valid URL paths.

3. Final Answer:

   /images/logo.png -> Option D

4. Quick Check:

   Public folder maps directly to root URL [OK]

Hint: Public folder files appear at root URL path [OK]

Common Mistakes:

• Using /assets prefix for public files
• Including 'public' in URL path
• Confusing assets and public URL paths

4. You placed a JavaScript file in app/assets/javascripts but it is not loading in your Rails app. What is a likely cause?

medium

A. You forgot to include the JavaScript pack or manifest in your layout

B. The file is missing from the public folder

C. JavaScript files must be placed in public/javascripts

D. Rails does not support JavaScript in assets folder

Solution

1. Step 1: Check how assets are loaded in Rails

   Files in app/assets/javascripts need to be referenced in your layout via a manifest or pack tag to load properly.

2. Step 2: Eliminate incorrect causes

   JavaScript files do not belong in public for processing. Rails fully supports JavaScript in assets folder.

3. Final Answer:

   You forgot to include the JavaScript pack or manifest in your layout -> Option A

4. Quick Check:

   Assets must be linked in layout to load [OK]

Hint: Always include asset manifests or packs in your layout [OK]

Common Mistakes:

• Expecting assets to load without linking in layout
• Placing JS files in wrong folders
• Thinking public folder is for processed assets

5. You want to add a favicon to your Rails app that loads instantly without asset pipeline processing. Where should you place the favicon file and how should you reference it in your HTML?

hard

A. Place in app/assets/images and use <%= favicon_link_tag 'favicon.ico' %>

B. Place in public folder root and use <link rel='shortcut icon' href='/favicon.ico'>

C. Place in app/assets/images and use <link rel='icon' href='/assets/favicon.ico'>

D. Place in public/images and use <%= image_tag 'favicon.ico' %>

Solution

1. Step 1: Choose folder for instant loading without processing

   Files in public are served directly, so placing favicon.ico in public root ensures instant loading.

2. Step 2: Reference favicon correctly in HTML

   Use a standard HTML <link> tag with href pointing to /favicon.ico for browsers to find it.

3. Final Answer:

   Place in public folder root and use <link rel='shortcut icon' href='/favicon.ico'> -> Option B

4. Quick Check:

   Favicon in public root + direct link = Place in public folder root and use <link rel='shortcut icon' href='/favicon.ico'> [OK]

Hint: Put favicon in public root and link with standard HTML tag [OK]

Common Mistakes:

• Placing favicon in assets and expecting instant load
• Using image_tag instead of link tag for favicon
• Referencing wrong URL path for favicon