Agile Web Development with Rails, Edition 5

12.1 Iteration H1: Capturing an Order 11.4 Iteration F4: Hide an Empty Cart

11.5 Iteration F5: Broadcasting Updates

create a channel

rails generate channel products
      create  app/channels/products_channel.rb
   identical  app/assets/javascripts/cable.js
      create  app/assets/javascripts/channels/products.coffee

create a channel

edit app/channels/products_channel.rb
class ProductsChannel < ApplicationCable::Channel
  def subscribed
    stream_from "products"
  end
 
  def unsubscribed
    # Any cleanup needed when channel is unsubscribed
  end
end

Update price when notified of price changes

edit app/assets/javascripts/channels/products.coffee
App.products = App.cable.subscriptions.create "ProductsChannel",
  connected: ->
    # Called when the subscription is ready for use on the server
 
  disconnected: ->
    # Called when the subscription has been terminated by the server
 
  received: (data) ->
    $(".store #main").html(data.html)

send updates when price changes

edit app/controllers/products_controller.rb
  def update
    respond_to do |format|
      if @product.update(product_params)
        format.html { redirect_to @product,
          notice: 'Product was successfully updated.' }
        format.json { render :show, status: :ok, location: @product }
 
        @products = Product.all
        ActionCable.server.broadcast 'products',
          html: render_to_string('store/index', layout: false)
      else
        format.html { render :edit }
        format.json { render json: @product.errors,
          status: :unprocessable_entity }
      end
    end
  end

Run tests

rails test
Run options: --seed 64579
 
# Running:
 
...............................
 
Finished in 1.044873s, 29.6687 runs/s, 63.1656 assertions/s.
 
31 runs, 66 assertions, 0 failures, 0 errors, 0 skips

Save our progress

git commit -a -m "AJAX"
[master cdfab4c] AJAX
 6 files changed, 60 insertions(+), 22 deletions(-)
 rewrite app/assets/javascripts/application.js (61%)
git tag iteration-f

12.1 Iteration H1: Capturing an Order 11.4 Iteration F4: Hide an Empty Cart