迁移:将整数改为引用而不丢失行

由 references 宏。

references :fo_creator

• 大人物 fo_creator_id

你的协会不起作用的原因很可能是 belongs_to :fo_creator 假定fkey列命名为 :fo_creator_id foreign_key 选项我会说你重命名列以消除这种不一致性是正确的。

class ChangeUsersFoCreatorToReference < ActiveRecord::Migration[5.2]
  def change
    rename_column :users, :fo_creator, :fo_creator_id
    change_column :users, :fo_creator_id, :bigint # optional
    add_foreign_key :users, :fo_creators
  end
end

如果 是自引用(引用用户表),创建fk时需要这样做:

# from table, to table
add_foreign_key :users, :users, column: :fo_creator_id

• ActiveRecord::ConnectionAdapters::SchemaStatements#add_reference
• ActiveRecord::Associations::ClassMethods#belongs_to
• ActiveRecord::ConnectionAdapters::SchemaStatements#add_foreign_key