Rails flash notice via ajax

Question

Long story short, I have a button. On clicking it, I want an ajax request to be triggered which gets flash[:notice] and displays it in a div in$

Here is my shortened

Answer 1

Here is an example that I got working, thanks to Rich Peck's answer. I needed to use flash.now to make sure the flash notice didn't persist.

AJAX trigger in the view:

<%= link_to "Email report", users_path, remote: true %>

Controller:

# app/controllers/users_controller
class UsersController < ApplicationController

  def index
    # do some things here

    respond_to do |format|
      format.js { flash.now[:notice] = "Here is my flash notice" }
    end
  end
end

Rendered view:

# app/views/users/index.js.erb
$("#flash").html('<%= j render partial: "shared/notice_banner" %>');

where the flash notice is displayed in the layout:

# app/views/layouts/application.html.erb
<div id="flash">
  <% if notice.present? %>
    <%= render partial: "shared/notice_banner" %>
  <% end %>
</div>


# app/views/shared/_notice_banner.html.erb
<div data-alert class="alert-box">
  <%= notice %>
  <a href="#" class="close">&times;</a>
</div>

Answer 2

Sessions

the same notice persists on the next clicks too

This is caused by the flash being stored in the session variable of Rails:

The flash is a special part of the session which is cleared with each request. This means that values stored there will only be available in the next request, which is useful for passing error messages etc.

The problem you have is that since I don't think ajax counts as a new request (need reference for this), the data will persist into the next time you request via HTTP.

--

Fix

I would initially try this:

def show
    respond_to do |format|
        format.js {  flash[:notice] = "my secret number "+rand(0,5)+" !" }
    end
end

The main problem you have is you're processing the flash variable in your JS using the ERB preprocessor. This is an issue as it means you won't be able to use asset precompile to help it work.

After looking at this question, why not try using the after_filter callback, like this:

#app/controllers/home_controller.rb
Class Home < ActionController::Base
   after_filter { flash.discard if request.xhr? }, only: :show

    def show
        respond_to do |format|
            format.js {  flash[:notice] = "my secret number "+rand(0,5)+" !" }
        end
    end
end

--

Update

You should include the success functionality in your show.js.erb:

#app/views/home/show.js.erb
$("#notice").html("<%= flash[:notice] %>");

This means you can remove the whole ajax call from the application.js, and replace with the remote: true for your search form:

#app/views/search/index.html.erb
<%= form_tag home_show_path, remote: true %>

The reason this works is because when you use the format.js respond block, Rails will load the [action].js.erb file in your views. Considering this only happens after the action has been completed, it's equivalent to the success function of your ajax.

By doing this, you'll be able to remove the entire ajax function from your application.js, and replace with the UJS version, as described above