Ruby on Rails数据库迁移不在MySQL表中创建外键

Question

我正试图在Ruby on Rails应用程序中修改数据库迁移。我正在使用MySQL作为我的数据库，并希望将外键添加到正在创建的表中。我正在使用下面的代码，并且正在遵循在适当的列上创建空值的规范，但没有外键约束被应用。

class CreateBookCheckOuts < ActiveRecord::Migration 
    def self.up 
    create_table :book_check_outs do |t| 
     t.integer :book_id, :null => false, :options => 
     "CONSTRAINT fk_book_check_out_books REFERENCES books(id)" 
     t.integer :person_id, :null => false, :options => 
     "CONSTRAINT fk_book_check_out_people REFERENCES people(id)" 
     t.datetime :OutDate, :null => false 
     t.datetime :ReturnDate, :null => true 

     t.timestamps 
    end 
    end 

    def self.down 
    drop_table :book_check_outs 
    end 
end 

Answer 1

您可以使用Foreigner宝石。

然后迁移改成这样：

class CreateBookCheckOuts < ActiveRecord::Migration 
    def self.up 
    create_table :book_check_outs do |t| 
     t.integer :book_id, :null => false 
     t.integer :person_id, :null => false 
     t.datetime :OutDate, :null => false 
     t.datetime :ReturnDate, :null => true 

     t.timestamps 
    end 
    add_foreign_key(:book_check_outs, :books) 
    add_foreign_key(:book_check_outs, :people) 
    end 

    def self.down 
    remove_foreign_key(:book_check_outs, :books) 
    remove_foreign_key(:book_check_outs, :people) 
    drop_table :book_check_outs 
    end 
end