Fragment caching in Ruby on Rails - Mini Project: Build & Apply

Fragment caching in Rails views

📖 Scenario: You are building a blog page in a Rails app. The page shows a list of posts. To make the page faster, you want to cache each post's HTML fragment so Rails doesn't have to render it every time.

🎯 Goal: Build a Rails view that uses fragment caching to store each post's HTML snippet. This will speed up page loading by reusing cached HTML for posts that haven't changed.

📋 What You'll Learn

Create a list of posts as an array of hashes in the controller

Set a cache key prefix variable in the view

Use cache helper with the cache key prefix and post id in the view partial

Wrap the post content HTML inside the cache block in the partial

💡 Why This Matters

🌍 Real World

Fragment caching is used in Rails apps to speed up rendering of views by storing parts of HTML that don't change often. This reduces server load and improves user experience.

💼 Career

Understanding fragment caching is important for Rails developers to optimize app performance and scalability in real projects.

1

Set up posts data in the controller

In the controller, create a variable called @posts and assign it an array of hashes with these exact entries: { id: 1, title: 'Hello Rails' }, { id: 2, title: 'Fragment Caching' }, { id: 3, title: 'Speed Up Views' }.

Ruby on Rails

# Your code here

Need a hint?

Use an instance variable @posts and assign it an array of hashes with the exact keys and values.

2

Add a cache key prefix variable in the view

In the view file, create a variable called cache_key_prefix and set it to the string 'posts_list'.

Ruby on Rails

# Your code here

Need a hint?

Just assign the string 'posts_list' to a variable named cache_key_prefix.

3

Use cache helper with cache key prefix and post id

In the view, write a for loop iterating over @posts with variable post. Inside the loop, use the cache helper with the key [cache_key_prefix, post[:id]] to wrap the post's title inside an <h2> tag.

Ruby on Rails

# Your code here

Need a hint?

Use a for loop with post over @posts. Use cache [cache_key_prefix, post[:id]] do to wrap the post title.

4

Complete the fragment caching with proper ERB tags

Ensure the view code uses proper ERB tags: open the Ruby code with <% %> and output the post title with <%= %>. The cache block should wrap the <h2> with the post title inside.

Ruby on Rails

  
    
  

# Your code here

Need a hint?

Make sure to use ERB tags correctly: <% %> for Ruby code and <%= %> to output the post title.