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What is caching and how to implement Caching in rails 6 and Rails 7

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Author: Himanshu Saxena

Views: 151

Caching is a critical aspect of web application performance optimization, as it helps reduce load times and server costs. Rails 6 and 7 offer robust caching strategies that can significantly improve the efficiency of your application. Let's explore these caching mechanisms and how to use them with examples.

1. Fragment Caching

Fragment caching stores view fragments in the cache to avoid regenerating the same content. It’s perfect for caching parts of pages that do not change often.

# app/views/articles/show.html.erb
<% cache @article do %>
  <h1><%= @article.title %></h1>
  <p><%= @article.body %></p>
<% end %>
In this example, the article's title and body are cached. The next time this view is rendered, Rails will use the cached content instead of regenerating it.

2. Action Caching

Action caching is similar to fragment caching but it caches the entire action's output. It’s useful when the same request returns identical responses.

class ArticlesController < ApplicationController
  caches_action :show

  def show
    @article = Article.find(params[:id])
  end
end

When the show action is called, the response is cached. Subsequent requests will serve the cached response.

3. Low-Level Caching

Low-level caching is used for caching arbitrary data, like the results of complex calculations or expensive database queries.

class Article < ApplicationRecord
  def self.expensive_query
    Rails.cache.fetch('expensive_query', expires_in: 12.hours) do
      # Simulate a costly operation
      where(created_at: Time.now - 1.year..Time.now)
    end
  end
end

In this example, expensive_query result is cached, and subsequent calls within 12 hours will retrieve the data from the cache rather than querying the database again.

4. Russian Doll Caching

Russian Doll Caching is a nested form of fragment caching. It’s efficient when you have nested elements that can benefit from individual caching.

# app/views/articles/show.html.erb
<% cache @article do %>
  <h1><%= @article.title %></h1>
  <% @article.comments.each do |comment| %>
    <% cache comment do %>
      <p><%= comment.body %></p>
    <% end %>
  <% end %>
<% end %>

In this example, both the article and its comments are cached separately, optimizing the performance of rendering nested elements.

Usage in Rails 7

Rails 7 continues to support all these caching mechanisms with improved performance. Additionally, it introduces Hotwire, which can further enhance caching efficiency by allowing partial page updates.

Example with Hotwire:

# app/views/articles/show.html.erb
<%= turbo_frame_tag "article_#{@article.id}" do %>
  <%= render 'article', article: @article %>
<% end %>

Using Hotwire’s Turbo Frames, only the changed parts of a page are updated, which can complement traditional caching strategies.

Conclusion

Caching in Rails 6 and 7 provides powerful tools to optimize web application performance. By strategically implementing fragment caching, action caching, low-level caching, and Russian Doll Caching, you can significantly improve your application's speed and reduce server load. Additionally, leveraging Hotwire in Rails 7 can further enhance the efficiency of your caching strategies.

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