Ruby on Rails数据库迁移不在MySQL表中创建外键

Question

我试图修改Ruby on Rails应用程序中的数据库迁移.我使用MySQL作为我的数据库,并希望将外键添加到正在创建的表中.我正在使用以下代码,并且在遵循在适当的列上创建空值的规范时,不应用外键约束.

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 gem.

然后将迁移更改为:

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