README.md

render_async

Speed up rendering Rails pages with this gem.

render_async renders partials to your views asynchronously. This is done through adding Javascript code that does AJAX request to your controller which then renders your partial into a Rails view.

Workflow:

1. user visits a Rails page
2. AJAX request on the controller action
3. controller renders a partial
4. partials renders in the place where you put render_async helper

Javascript is injected into <%= content_for :render_async %> so you choose where to put it.

Installation

Add this line to your application's Gemfile:

gem 'render_async'

And then execute:

$ bundle install

Usage

1. Include render_async view helper somewhere in your views:

   # app/views/comments/show.html.erb
   
   <%= render_async comment_stats_path %>

2. Then create a route that will config/routes.rb

   # config/routes.rb
   
   get :comment_stats, :controller => :comments

3. Fill in the logic in your controller

   # app/controllers/comments_controller.rb
   
   def comment_stats
     @stats = Comment.get_stats
   
     render :partial => "comment_stats"
   end

4. Create a partial that will render

   # app/views/comments/_comment_stats.html.erb
   
   <div class="col-md-6">
     <%= @stats %>
   </div>

5. Add content_for in your base view file

   # application.html.erb
   
   <%= content_for :render_async %>

Advanced usage

Passing in HTML options

render_async takes two arguments, path and html_options.

• path is the AJAX-capable controller action you're looking to call via GET. e.g. comments_stats_path, posts_path, etc.
• html_options is an optional hash that gets passed to a rails javascript_tag, to drop html tags into the script element.

Example of utilizing html_options with a nonce:

<%= render_async users_path, nonce: 'lWaaV6eYicpt+oyOfcShYINsz0b70iR+Q1mohZqNaag=' %>

Rendered code in the view:

<div id="render_async_18b8a6cd161499117471">
</div>

<script nonce="lWaaV6eYicpt+oyOfcShYINsz0b70iR+Q1mohZqNaag=">
//<![CDATA[

    (function($){
      $.ajax({ url: "/users" }).always(function(response) {
        $("#render_async_18b8a6cd161499117471").replaceWith(response);
      });
    }(jQuery));

//]]>
</script>

Passing in a placeholder

render_async can be called with a block that will act as a placeholder before your AJAX call finishes.

Example of passing in a block:

<%= render_async users_path do %>
  <h1>Users are loading...</h1>
<% end %>

Rendered code in the view:

<div id="render_async_14d7ac165d1505993721">
  <h1>Users are loading...</h1>
</div>

<script>
//<![CDATA[

    (function($){
      $.ajax({ url: "/users" }).always(function(response) {
        $("#render_async_14d7ac165d1505993721").replaceWith(response);
      });
    }(jQuery));

//]]>
</script>

After AJAX is finished, placeholder will be replaced with the request's response.

Caching

render_async can utilize view fragment caching to avoid extra AJAX calls.

In your views:

# app/views/comments/show.html.erb

# note 'render_async_cache' instead of standard 'render_async'
<%= render_async_cache comment_stats_path %>

# app/views/comments/_comment_stats.html.erb

<% cache render_async_cache_key(request.path), :skip_digest => true do %>
  <div class="col-md-6">
    <%= @stats %>
  </div>
<% end %>

• The first time the page renders, it will make the AJAX call.
• Any other times (until the cache expires), it will render from cache instantly, without making the AJAX call.
• You can expire cache simply by passing :expires_in in your view where you cache the partial

Development

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Contributing

Bug reports and pull requests are welcome on GitHub at https://github.com/renderedtext/render_async.

License

The gem is available as open source under the terms of the MIT License.

Contributors

Thanks goes to these wonderful people (emoji key):

Nikola Đuza 💬 🐛 💻 📖 💡 👀	Colin 💻 📖	Kasper Grubbe 💻	Sai Ram Kunala 📖	Josh Arnold 💻 📖	Elad Shahar 💻

This project follows the all-contributors specification. Contributions of any kind welcome!