Question

class User < ApplicationRecord
  has_many :created_events, :foreign_key => "creator_id", :class_name => "Event"
end

class Event < ApplicationRecord
  belongs_to :creator, :class_name => "User"
end

当我尝试使用创建者创建活动时，会显示ActiveModel::UnknownAttributeError: unknown attribute 'creator_id' for Event. 我运行rails db:migrate但仍然没有创建外键并添加到事件表。我究竟做错了什么？我到处看着。

$ rails db：migrate：status

 Status   Migration ID    Migration Name
--------------------------------------------------
   up     20170625163737  Create users
   up     20170625170905  Create events
   up     20170625171959  Add description to event
   up     20170625174531  Add creator id to events

但是，迁移文件显示没有添加：

class AddCreatorIdToEvents < ActiveRecord::Migration[5.1]
  def change
  end
end

Answer 1

您尚未正确定义关联。您的模型应如下所示：

class User < ApplicationRecord
  has_many :events, :foreign_key => "creator_id", :class_name => "Event"
end

class Event < ApplicationRecord
  belongs_to :creator, :foreign_key => "creator_id", :class_name => "User"
end

同样foreign_key始终存在于子表中。尝试创建如下的事件。

考虑用户已登录。

current_user.events.create(event_params)

请参阅this以获取与协会相关的帮助。

Answer 2

您的模型应如下所示：

class User < ApplicationRecord
  has_many :created_events, :foreign_key => "creator_id", :class_name =>    "Event"
end

class Event < ApplicationRecord
  belongs_to :creator, :foreign_key => "creator_id", :class_name => "User"
end

ActiveModel :: UnknownAttributeError：未知属性＆＃39; creator_id＆＃39;对于事件

2 个答案: