ruby-on-rails – 相应的回滚是什么?
发布时间:2020-12-17 03:20:09 所属栏目:百科 来源:网络整理
导读:我有以下ActiveRecord迁移: class CreateSubjects ActiveRecord::Migration def self.up create_table :subjects do |t| t.string :title t.timestamps end change_table :projects do |t| t.references :subjects end end def self.down drop_table :subje
我有以下ActiveRecord迁移:
class CreateSubjects < ActiveRecord::Migration def self.up create_table :subjects do |t| t.string :title t.timestamps end change_table :projects do |t| t.references :subjects end end def self.down drop_table :subjects remove_column :projects,:subjects_id #defeats the purpose of having references end end 我其实喜欢参考风格.不幸的是,我无法在self.down部分找到与回滚等效的回滚.如果我写remove_column:projects,:subjects_id我也可以写t.integer:subjects_id,这会让它更安全. 解决方法
它被称为
remove_references.
t.remove_references :subjects 小心! Rails按惯例使用单数,应该是: def self.up create_table :subjects do |t| t.string :title t.timestamps end change_table :projects do |t| t.references :subject end end def self.down drop_table :subjects change_table :projects do |t| t.remove_references :subject end end (编辑:李大同) 【声明】本站内容均来自网络,其相关言论仅代表作者个人观点,不代表本站立场。若无意侵犯到您的权利,请及时与联系站长删除相关内容! |