Medżik js

decrement.js.erb

<!-- app/views/line_items/decrement.js.erb -->
$('#cart').html("<%= escape_javascript(render(@cart)) %>");
$('#current_item').css({'background-color':'#88ff88'}).animate({'background-color':'#114411'}, 1000);
if ($('#cart tr').length==1) {
    // Hide the cart
    $('#cart').hide('blind', 1000);    
}

line_item.rb

class LineItem < ActiveRecord::Base
  belongs_to :order
  belongs_to :product
  belongs_to :cart
  attr_accessible :cart_id, :product_id

  def total_price
    product.price * quantity
  end

  def decrement_quantity
    if self.quantity > 1
      self.update_attribute(:quantity, self.quantity -=1)
    else
      self.destroy
    end
    self
  end
end

line_items_controller.rb

# app/controllers/line_items_controller.rb
class LineItemsController < ApplicationController

  # GET /line_items
  # GET /line_items.json
  def index
    @line_items = LineItem.all

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @line_items }
    end
  end

  # GET /line_items/1
  # GET /line_items/1.json
  def show
    @line_item = LineItem.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.json { render json: @line_item }
    end
  end

  # GET /line_items/new
  # GET /line_items/new.json
  def new
    @line_item = LineItem.new

    respond_to do |format|
      format.html # new.html.erb
      format.json { render json: @line_item }
    end
  end

  # GET /line_items/1/edit
  def edit
    @line_item = LineItem.find(params[:id])
  end

  # POST /line_items
  # POST /line_items.json
  def create
    @cart = current_cart
    product = Product.find(params[:product_id])
    @line_item = @cart.add_product(product.id)
    @line_item.product = product

    respond_to do |format|
      if @line_item.save
        format.html { redirect_to store_url }
        format.js   { @current_item = @line_item }
        format.json { render json: @line_item,
          status: :created, location: @line_item }
      else
        format.html { render action: "new" }
        format.json { render json: @line_item.errors,
          status: :unprocessable_entity }
      end
    end
  end

  # PUT /line_items/1
  # PUT /line_items/1.json
  def update
    @line_item = LineItem.find(params[:id])

    respond_to do |format|
      if @line_item.update_attributes(params[:line_item])
        format.html { redirect_to @line_item, notice: 'Line item was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: "edit" }
        format.json { render json: @line_item.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /line_items/1
  # DELETE /line_items/1.json
  def destroy
    @line_item = LineItem.find(params[:id])
    @line_item.destroy

    respond_to do |format|
      format.html { redirect_to line_items_url }
      format.json { head :no_content }
    end
  end

  def decrement
    @line_item = LineItem.find(params[:id])
    @cart = @line_item.cart
    respond_to do |format|
      if @line_item.decrement_quantity
        format.html { redirect_to store_path, notice: 'Line item was successfully updated.' }
        format.js { @current_item = @line_item }
      end
    end
  end
end

routes.rb

  resources :line_items do
    member do
      put :decrement
    end
  end