rails 多态

最新推荐文章于 2020-03-01 11:56:23 发布

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最新推荐文章于 2020-03-01 11:56:23 发布

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原文链接：http://www.cnblogs.com/lizhenjiang/p/7111458.html

本文介绍了一个使用Ruby on Rails实现的模型关联案例，包括Employee、Product和Picture三个模型之间的多态关联。具体展示了如何创建Product实例并为其关联Picture，以及如何查询这些关联的数据。

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rails g model employee name:string

rails g model product name:string

rails g model picture name:string imageable_id:integer imageable_type:string

class Employee < ApplicationRecord
has_many :pictures, :as => :imageable
end

class Product < ApplicationRecord
has_many :pictures, :as => :imageable
end

class Picture < ApplicationRecord
belongs_to :imageable, :polymorphic => true
end

irb(main):001:0> product = Product.create name: "iphone"

(0.1ms) begin transaction

SQL (1.1ms) INSERT INTO "products" ("name", "created_at", "updated_at") VALUES (?, ?, ?) [["name", "iphone"], ["created_at", "2017-07-03 07:26:45.164785"], ["updated_at", "2017-07-03 07:26:45.164785"]]

(0.7ms) commit transaction

=> #<Product id: 1, name: "iphone", created_at: "2017-07-03 07:26:45", updated_at: "2017-07-03 07:26:45">

irb(main):002:0> picture = product.pictures.create name: 'pic1'

(0.1ms) begin transaction

Product Load (0.2ms) SELECT "products".* FROM "products" WHERE "products"."id" = ? LIMIT ? [["id", 1], ["LIMIT", 1]]

SQL (0.7ms) INSERT INTO "pictures" ("name", "imageable_id", "imageable_type", "created_at", "updated_at") VALUES (?, ?, ?, ?, ?) [["name", "pic1"], ["imageable_id", 1], ["imageable_type", "Product"], ["created_at", "2017-07-03 07:27:47.046831"], ["updated_at", "2017-07-03 07:27:47.046831"]]

(0.7ms) commit transaction

=> #<Picture id: 1, name: "pic1", imageable_id: 1, imageable_type: "Product", created_at: "2017-07-03 07:27:47", updated_at: "2017-07-03 07:27:47">

irb(main):003:0> picture

=> #<Picture id: 1, name: "pic1", imageable_id: 1, imageable_type: "Product", created_at: "2017-07-03 07:27:47", updated_at: "2017-07-03 07:27:47">

转载于:https://www.cnblogs.com/lizhenjiang/p/7111458.html