Remote True is Magic

I had a really fun time this weekend building a small side project with Sophie DeBenedetto, Jeremy Sklarsky, and Rachel Nackman. We learned a lot of very cool things that you can do with Rails + jQuery, but the coolest was easily remote: true. This one little option is crazy powerful. Case in point: by adding remote: true to our Search form, our searches.js file went from this:

$(function () { submitListener(); })

function submitListener () {
  $('#new_search').on('submit', submitSearch);
}

function submitSearch (e) {
  e.preventDefault();
  var url = $(this).attr('action');
  var $form = $('form#new_search');

  $.ajax(url, {
    method: 'POST',
    url: url,
    data: $form.serialize(),
    dataType: 'script',
    complete: function(response){}
  });
}

to this:


That’s right. Adding remote: true allowed us to nix our entire jQuery listener + ajax request for that form, because all that functionality is contained within remote: true.

Taylor Swift Mind Blown

So how’s it work? Well, if this is your first remote: true rodeo, you might be thinking something like this:

Remote True is MAGIC

Let’s demystify it a bit. The Rails documentation puts things pretty simply:

Rails provides a bunch of view helper methods written in Ruby to assist you in generating HTML [including Ajax helpers]. …The Rails “Ajax helpers” are in two parts: the JavaScript half and the Ruby half.

rails.js provides the JavaScript half, and the regular Ruby view helpers add appropriate tags to your DOM. The CoffeeScript in rails.js then listens for these attributes and attaches appropriate handlers.

To recap, when you use remote: true inside a view helper method, like form_for or link_to, Rails automatically adds a jQuery listener to that object (the form or the link) and executes the appropriate action (such as e.preventDefault(); and e.stopPropogation();, as two examples). With that basic functionality taken care of, you’re then free to add your own jQuery actions as needed within a .js.erb view file, after making sure your controller will respond_to both format.js and format.html.

That explanation was pretty abstract, so let’s look at a concrete example of how to implement remote: true inside some actual working code. I’ll step through pieces of our code below, and you can always check out the repo here for the full source.

Step 1: Add remote: true to your form.

<!-- index.html.erb -->

<h1>Am I Ruby?</h1>
<%= form_for(@search, remote: true) do |f| %>
  <%= f.text_field :keyword, id: 'keyword' %>
  <%=f.submit "Search", class: "search-btn"%>
<% end %>
<section id="result"></section>

Originally, our form_for method took a single argument, @search. We simply added the additional option remote: true to that argument. Now our form submits data (formerly expressed as data: $form.serialize() inside the ajax method) to the server without refreshing the page. However, you won’t see anything happen in your browser yet, because our contorller doesn’t yet know how exactly to respond_to the successful ajax request. We’ll need to make some adjuments there next.

Step 2: Update your controller action to respond_to format.js.

class SearchesController < ApplicationController
  def create
    @result = Search.new.am_i_ruby(params[:search][:keyword])
    respond_to do |format|
      format.html
      format.js
    end
  end
end

Before “ajaxifying” our code, our create action only had one line of code setting the @result variable. Note: We could also have explicitly told it to render a specific view, but since by default, the create action will render the create.html.erb view, we had left that line out.

# non-ajax'd SearchController create action
def create
  @result = Search.new.am_i_ruby(search_params)
end

Now that we’re using remote: true, we don’t want to render a view; we want to execute a jQuery function of our choosing. So we replace the render command and with respond_to instructions for each format we want our controller to serve. Here, our controller can serve html AND Javascript responses to the ajax success function.

Step 3: Add create.js.erb file

In your create.js.erb view file, you can add whatever actions you want to happen upon a successful ajax request. In our case, we wanted to display the result of our search form (which was querying BuiltWith.com and returning “yes” or “no”, depending on whether or not the domain we sent it included Ruby code in its stack).

$('#result').hide().html('<%= j @result %>').fadeIn(250);

Our jQuery command is doing the following:

  • selecting the div with “id=result”
  • upon document ready, hiding that div
  • listening for successful form submission (performed behind-the-scenes by remote: true)
  • upon successful ajax request, inserting @result into DOM html inside div#result with a nice 250ms count fade-in effect

Check out the code in action here: www.amiruby.com

More resources:

  1. Railscasts #136 - jQuery & Ajax
  2. Railscasts #205 - Unobtrusive Javascript
  3. Alfajango - Rails Remote Links and Forms
  4. CodeBeerStartups - Ajaxify your Site With Remote True
  5. (Flatiron alum) Koren Leslie Cohen - Remote True in Rails Forms
Written on March 29, 2015