rails 模型 has_many 本身 [英] rails model has_many of itself

问题描述

我有一个事件模型.事件可以有父事件，从模型中的列 (parent_event_id) 中设置.我需要能够在模型上做 has_many :event，所以我可以做，例如，event.child_event 或 event.parent_event>.但是我的谷歌搜索没有那么好.

I have a event model. Events can have parent events, set from a column in the model (parent_event_id). I need to be able to do has_many :event on the model, so I can just do, for example, event.child_event or event.parent_event. But my googling hasn't worked out that well.

我的模型:

class Event < ActiveRecord::Base
    attr_accessible :days_before, :event_name, :event_date, :list_id, :recipient_email, :recipient_name, :parent_event_id, :is_deleted, :user_id

    belongs_to :user
    has_many :event_email
    has_many :event
end

我的架构:

create_table "events", :force => true do |t|
    t.datetime "event_date"
    t.integer  "days_before"
    t.string   "recipient_email"
    t.integer  "list_id"
    t.string   "recipient_name"
    t.datetime "created_at",                         :null => false
    t.datetime "updated_at",                         :null => false
    t.integer  "user_id"
    t.string   "event_name"
    t.integer  "parent_event_id"
    t.boolean  "is_deleted",      :default => false
end

推荐答案

这是一个自引用模型，你可以试试这样的:

This is a self-referential model, you can try something like this:

class Event < ActiveRecord::Base
  belongs_to :parent, :class_name => "Event", :foreign_key => "parent_event_id"
  has_many :child_events, :class_name => "Event", :foreign_key => "child_event_id"
end

这样就可以调用@event.parent 来获取一个ActiveRecord Event 对象，调用@event.child_events 来获取一个ActiveRecord 的Event 对象集合

That way, you can call @event.parent to get an ActiveRecord Event object and @event.child_events to get an ActiveRecord collection of Event objects

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