Dash of ajax

Add a Dash of Ajax

Jason Noblehttp://jasonnoble.org

Partial Templates

• Methods for views• Move a portion of your view to a separate file• Invoke a given partial from multiple locations– Another view– Controller

app/views/carts/show.html.erb

Rails render method

• takes a collection as an argument• renders a partial view for each item• Partials filenames start with with _– _line_item.html.erb

• Inside the partial we will have a variable available the same name as the partial– _line_item partial has variable line_item

app/views/line_items/_line_item.html.erb

app/views/carts/_cart.html.erb

app/views/layouts/application.html.erb

app/controllers/store_controller.rb

public/stylesheets/depot.css

app/controllers/line_items_controller.rb

app/views/store/index.html.erb

• Modify the Add to Cart to use Ajax

app/controllers/line_items_controller.rb

• Modify create to respond to JavaScript

app/views/line_items/create.js.rjs

• Render JavaScript

• page is a JavaScript generator• Replaces HTML content of the id cart with the

rendered HTML

• Now clicking Add to Cart doesn’t refresh the page, just the cart div

Highlight Changes

• Product owner wants a visual cue that the cart has been updated

• We’ll use the script.aculo.us’ provided yellow fade technique

• See other effects at http://madrobby.github.com/scriptaculous/demos/

app/controllers/line_items_controller.rb

• We need to know what item is being updated

app/views/line_items/_line_item.html.erb

app/views/line_items/create.js.rjs

• Current Item will be tagged with id=“current_item”

• Add Visual Effect via JavaScript

Hide Empty Carts

• Customer would like to hide the cart if it is empty

• We’ll do this first via not rendering the HTML if the cart is empty

• Then we’ll make it smoother by adding another JavaScript effect

app/views/carts/_cart.html.erb

app/views/line_items/create.js.rjs

app/models/cart.rb

app/views/layout/application.html.erb

app/helpers/application_helper.rb

app/views/layouts/application.html.erb

• Use hidden_div_if helper

app/controllers/carts_controller.rb

• Don’t display “Your cart is empty” flash

Run tests

• rake test– 1 failure, 9 errors

• You can see errors as well– http://localhost:3000/products

• @cart is not being set in the products controller– Let’s make it optional

app/views/layouts/application.html.erb

Run tests

• rake test– 1 failure, 0 errors

• We changed a redirect in the line items controller, we need to update the test

test/functional/line_items_controller_test.rb

Testing ajax

• test/functional/line_items_controller_test.rb

What we did

• Moved shopping cart into sidebar• Used :remote => true to Ajaxify our buttons• Used RJS template to update page• Added highlight effect to show changes• Wrote helper to hide cart when it’s empty• Wrote tests to verify Ajax actions

Homework

• Make clicking the image of the book add the item to the cart via Ajax

• Change Empty Cart action to use Ajax and blind_up effect

• Experiment with other visual effects available• Add a link in the cart next to each item. Clicking the

item should decrement the quantity of that item.• Write a view test to verify the empty cart is not

viewable