我正在尝试修改 Ruby on Rails 应用程序中的数据库迁移。我使用 MySQL 作为数据库,并且想将外键添加到正在创建的表中。我正在使用以下代码,虽然遵循在适当列上创建空值的规范,但没有应用外键约束。
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
您可以使用外国人 https://github.com/matthuhiggins/foreigner gem.
然后将您的迁移更改为:
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
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