Agile Web Development with Rails, Edition 5

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) ->

    document.getElementsByTagName("main")[0].innerHTML = 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 1099

# Running:

...............................

Finished in 0.829654s, 37.3650 runs/s, 80.7566 assertions/s.

31 runs, 67 assertions, 0 failures, 0 errors, 0 skips

Save our progress

git commit -a -m "AJAX"

[master 6e378ba] AJAX

 3 files changed, 26 insertions(+), 7 deletions(-)

git tag iteration-f