belongs_to的有：将class_name选项失败 [英] belongs_to with :class_name option fails

问题描述

我不知道哪里出了问题，但我不能让belongs_to的的工作：将class_name选项。可能有人开导我。非常感谢！

下面是我的code剪断。

 类CreateUsers＆LT; ActiveRecord的::迁移
    高清self.up
        CREATE_TABLE：用户做| T |
            t.text：名称
        结束
    结束

    高清self.down
        drop_table：用户
    结束
结束

################################################## ###

类CreateBooks＆LT; ActiveRecord的::迁移
    高清self.up
        CREATE_TABLE：书做| T |
            t.text：标题
            t.integer：AUTHOR_ID，：空=＆GT;假
        结束
    结束

    高清self.down
        drop_table：书籍
    结束
结束

################################################## ###

类用户的LT;的ActiveRecord :: Base的
    的has_many：书籍
结束

################################################## ###

类Book＆LT;的ActiveRecord :: Base的
    belongs_to的：作者：=将class_name＆GT; 用户，：验证=＆GT;真正
结束

################################################## ###

类BooksController中＆LT;的ApplicationController
    DEF创建
        用户= User.new（{：名称=＆GT;吴宇森'}）
        user.save
        @failed_book = Book.new（{：标题=＆GT;失败！，：作者=＆GT; @user}）
        @ failed_book.save＃失踪AUTHOR_ID
        @success_book = Book.new（{：标题=＆GT;'好天'，：AUTHOR_ID =＆GT; @ user.id}）
        @ success_book.save＃没有错误！
    结束
结束
 

环境：

1.9.1-P387 Rails的2.3.5

解决方案

 类用户的LT;的ActiveRecord :: Base的
  的has_many：书：foreign_key =＆GT; AUTHOR_ID
结束

类Book＆LT;的ActiveRecord :: Base的
  belongs_to的：作者：=将class_name＆GT; 用户，：foreign_key =＆GT; AUTHOR_ID'，：验证=＆GT;真正
结束
 

做的最好的事情是改变你的迁移和修改 AUTHOR_ID 到 USER_ID 。然后你就可以删除：foreign_key 选项

I have no idea what went wrong but I can't get belongs_to work with :class_name option. Could somebody enlighten me. Thanks a lot!

Here is a snip from my code.

class CreateUsers < ActiveRecord::Migration
    def self.up
        create_table :users do |t|
            t.text :name
        end
    end

    def self.down
        drop_table :users
    end
end

#####################################################

class CreateBooks < ActiveRecord::Migration
    def self.up
        create_table :books do |t|
            t.text :title
            t.integer :author_id, :null => false
        end
    end

    def self.down
        drop_table :books
    end
end

#####################################################

class User < ActiveRecord::Base
    has_many: books
end

#####################################################

class Book < ActiveRecord::Base
    belongs_to :author, :class_name => 'User', :validate => true
end

#####################################################

class BooksController < ApplicationController
    def create
        user = User.new({:name => 'John Woo'})
        user.save
        @failed_book = Book.new({:title => 'Failed!', :author => @user})
        @failed_book.save # missing author_id
        @success_book = Book.new({:title => 'Nice day', :author_id => @user.id})
        @success_book.save # no error!
    end
end

environment:

ruby 1.9.1-p387 Rails 2.3.5

解决方案

class User < ActiveRecord::Base
  has_many :books, :foreign_key => 'author_id'
end

class Book < ActiveRecord::Base
  belongs_to :author, :class_name => 'User', :foreign_key => 'author_id', :validate => true
end

The best thing to do is to change your migration and change author_id to user_id. Then you can remove the :foreign_key option.

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