Ruby on Rails - AJAX

Ruby on Rails is a popular web framework that includes support for AJAX functionality. AJAX is a technique that allows for asynchronous communication between the client and server, making web applications more responsive and interactive. In this article, we will explore how Ruby on Rails integrates with AJAX and how it can be used to create dynamic web applications.

AJAX in Rails

Rails provides built-in support for AJAX through its Unobtrusive JavaScript (UJS) library. The UJS library provides helpers that allow developers to easily add AJAX functionality to their applications without having to write lots of client-side JavaScript code. The helpers generate the necessary JavaScript code to make AJAX requests and handle the responses in a seamless way.

AJAX Helpers

Rails provides a number of helpers for working with AJAX:

• remote_form_for: generates a form that submits via AJAX.
• link_to: generates a link that makes an AJAX request.
• button_to: generates a button that makes an AJAX request.
• form_tag: generates a form that can submit via AJAX.

These helpers can be used to add AJAX functionality to a Rails application without having to write any JavaScript code. For example, to add AJAX support to a form, you can use the following code:

<%= remote_form_for @post, url: posts_path, method: :post do |f| %>
  <%= f.text_field :title %>
  <%= f.text_area :content %>
  <%= f.submit "Create Post" %>
<% end %>

This will generate a form that submits via AJAX and handles the response seamlessly.

AJAX Responses

When using AJAX in Rails, the server can respond with HTML, JSON, or JavaScript. Rails provides support for all of these response types through its respond_to and respond_with methods. For example, to respond with HTML, you can use the following code:

def create
  @post = Post.new(params[:post])

  respond_to do |format|
    if @post.save
      format.html { redirect_to @post }
      format.json { render json: @post }
      format.js
    else
      format.html { render :new }
      format.json { render json: @post.errors, status: :unprocessable_entity }
      format.js   { render 'error' }
    end
  end
end

This code will respond with HTML, JSON or JavaScript depending on the request format, as determined by the Accept header.

AJAX and Turbolinks

Turbolinks is a gem that provides fast page loading by only replacing the body of a page, rather than reloading the entire page on each request. However, this can cause issues with AJAX requests, as the JavaScript and CSS files are not loaded with the new body, potentially breaking the AJAX functionality.

To solve this issue, Rails provides a data-turbolinks-track attribute that can be added to AJAX links and forms. This tells Turbolinks to track the AJAX request and reload the necessary JavaScript and CSS files.

<%= link_to "Show Post", post_path(@post), remote: true, "data-turbolinks-track": "reload" %>

Conclusion

Ruby on Rails provides powerful support for AJAX functionality through its Unobtrusive JavaScript library. With the help of built-in helpers, developers can easily add AJAX functionality to their applications without having to write lots of client-side JavaScript code. By responding with HTML, JSON or JavaScript, Rails provides a flexible way to handle AJAX requests. Finally, by adding the data-turbolinks-track attribute, Rails allows AJAX requests to work seamlessly with Turbolinks.