64 行
1.7 KiB
Ruby
64 行
1.7 KiB
Ruby
#---
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# Excerpted from "Agile Web Development with Rails",
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# published by The Pragmatic Bookshelf.
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# Copyrights apply to this code. It may not be used to create training material,
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# courses, books, articles, and the like. Contact us if you are in doubt.
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# We make no guarantees that this code is fit for any purpose.
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# Visit http://www.pragmaticprogrammer.com/titles/rails4 for more book information.
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#---
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$: << File.dirname(__FILE__)
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require "connect"
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require "logger"
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#ActiveRecord::Base.logger = Logger.new(STDERR)
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require "rubygems"
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require "active_record"
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ActiveRecord::Schema.define do
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create_table :products, :force => true do |t|
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t.string :title
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t.text :description
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# ...
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t.integer :line_items_count, :default => 0
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end
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create_table :line_items, :force => true do |t|
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t.integer :product_id
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t.integer :order_id
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t.integer :quantity
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t.decimal :unit_price, :precision => 8, :scale => 2
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end
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end
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class Product < ActiveRecord::Base
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has_many :line_items
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end
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class LineItem < ActiveRecord::Base
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belongs_to :product, :counter_cache => true
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end
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product = Product.create(:title => "Programming Ruby",
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:description => " ... ")
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line_item = LineItem.new
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line_item.product = product
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line_item.save
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puts "In memory size = #{product.line_items.size}" #=> 0
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puts "Refreshed size = #{product.line_items(:refresh).size}" #=> 1
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LineItem.delete_all
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Product.delete_all
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product = Product.create(:title => "Programming Ruby",
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:description => " ... ")
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product.line_items.create
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puts "In memory size = #{product.line_items.size}" #=> 1
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puts "Refreshed size = #{product.line_items(:refresh).size}" #=> 1
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