Agile Web Development with Rails, Edition 5

11.5 Iteration F5: Broadcasting Updates

create a channel

edit app/channels/application_cable/products_channel.rb

class ProductsChannel < ActionCable::Channel::Base

  def subscribed

    stream_from "products"

end

end

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

Update price when notified of price changes

edit app/assets/javascripts/products.coffee

# Place all the behaviors and hooks related to the matching controller here.

# All this logic will automatically be available in application.js.

# You can use CoffeeScript in this file: http://coffeescript.org/

App.productsChannel =

  App.cable.subscriptions.create { channel: "ProductsChannel" },

    received: (data) -> $(".store #main").html(data.html)

Run tests... oops.

rails test

Run options: --seed 61122

# Running:

..E

Error:

CartsControllerTest#test_should_get_index:

ActionView::Template::Error: undefined method `line_items' for nil:NilClass

    app/views/layouts/application.html.erb:21:in `_app_views_layouts_application_html_erb__1587492418220410426_55785240'

    test/controllers/carts_controller_test.rb:9:in `block in <class:CartsControllerTest>'

bin/rails test test/controllers/carts_controller_test.rb:8

....E

Error:

LineItemsControllerTest#test_should_get_index:

ActionView::Template::Error: undefined method `line_items' for nil:NilClass

    app/views/layouts/application.html.erb:21:in `_app_views_layouts_application_html_erb__1587492418220410426_57562380'

    test/controllers/line_items_controller_test.rb:9:in `block in <class:LineItemsControllerTest>'

bin/rails test test/controllers/line_items_controller_test.rb:8

Error:

LineItemsControllerTest#test_should_get_new:

ActionView::Template::Error: undefined method `line_items' for nil:NilClass

    app/views/layouts/application.html.erb:21:in `_app_views_layouts_application_html_erb__1587492418220410426_58002060'

    test/controllers/line_items_controller_test.rb:14:in `block in <class:LineItemsControllerTest>'

bin/rails test test/controllers/line_items_controller_test.rb:13

Error:

LineItemsControllerTest#test_should_get_edit:

ActionView::Template::Error: undefined method `line_items' for nil:NilClass

    app/views/layouts/application.html.erb:21:in `_app_views_layouts_application_html_erb__1587492418220410426_62666420'

    test/controllers/line_items_controller_test.rb:43:in `block in <class:LineItemsControllerTest>'

bin/rails test test/controllers/line_items_controller_test.rb:42

...E

Error:

LineItemsControllerTest#test_should_show_line_item:

ActionView::Template::Error: undefined method `line_items' for nil:NilClass

    app/views/layouts/application.html.erb:21:in `_app_views_layouts_application_html_erb__1587492418220410426_63426320'

    test/controllers/line_items_controller_test.rb:38:in `block in <class:LineItemsControllerTest>'

bin/rails test test/controllers/line_items_controller_test.rb:37

...E

Error:

ProductsControllerTest#test_should_get_index:

ActionView::Template::Error: undefined method `line_items' for nil:NilClass

    app/views/layouts/application.html.erb:21:in `_app_views_layouts_application_html_erb__1587492418220410426_58994100'

    test/controllers/products_controller_test.rb:18:in `block in <class:ProductsControllerTest>'

bin/rails test test/controllers/products_controller_test.rb:17

Error:

ProductsControllerTest#test_should_get_new:

ActionView::Template::Error: undefined method `line_items' for nil:NilClass

    app/views/layouts/application.html.erb:21:in `_app_views_layouts_application_html_erb__1587492418220410426_57968020'

    test/controllers/products_controller_test.rb:23:in `block in <class:ProductsControllerTest>'

bin/rails test test/controllers/products_controller_test.rb:22

.E

Error:

ProductsControllerTest#test_should_get_edit:

ActionView::Template::Error: undefined method `line_items' for nil:NilClass

    app/views/layouts/application.html.erb:21:in `_app_views_layouts_application_html_erb__1587492418220410426_56545440'

    test/controllers/products_controller_test.rb:43:in `block in <class:ProductsControllerTest>'

bin/rails test test/controllers/products_controller_test.rb:42

Error:

ProductsControllerTest#test_should_show_product:

ActionView::Template::Error: undefined method `line_items' for nil:NilClass

    app/views/layouts/application.html.erb:21:in `_app_views_layouts_application_html_erb__1587492418220410426_55456420'

    test/controllers/products_controller_test.rb:38:in `block in <class:ProductsControllerTest>'

bin/rails test test/controllers/products_controller_test.rb:37

........

Finished in 1.091766s, 27.4784 runs/s, 57.7047 assertions/s.

30 runs, 63 assertions, 0 failures, 9 errors, 0 skips