钢轨本身模型的has_many [英] rails model has_many of itself

问题描述

我有一个事件模型。事件可以有父母的事件，从模型（parent_event_id）一列设置。我需要能够做到的has_many：事件的模式，所以我可以做，例如， event.child_event 或 event.parent_event 。但我的谷歌搜索没有制定出那么好。

我的模型：

 类事件＆LT;的ActiveRecord :: Base的
    attr_accessible：days_before，：EVENT_NAME，：EVENT_DATE，：list_id，：RECIPIENT_EMAIL，：RECIPIENT_NAME，：parent_event_id，：IS_DELETED，：USER_ID

    belongs_to的：用户
    的has_many：event_email
    的has_many：事件
结束
 

我的架构：

  CREATE_TABLE事件，：力=＆GT;真做| T |
    t.datetimeEVENT_DATE
    t.integerdays_before
    t.stringRECIPIENT_EMAIL
    t.integerlist_id
    t.stringRECIPIENT_NAME
    t.datetimecreated_at：空=＆GT;假
    t.datetime的updated_at：空=＆GT;假
    t.integerUSER_ID
    t.stringEVENT_NAME
    t.integerparent_event_id
    t.booleanIS_DELETED：默认=＆GT;假
结束
 

解决方案

这是一种自我指涉的模式，你可以尝试这样的：

 类事件＆LT;的ActiveRecord :: Base的
  belongs_to的：父母，：将class_name =＆GT; 事件，：foreign_key =＆GT; parent_event_id
  的has_many：child_events，：将class_name =＆GT; 事件，：foreign_key =＆GT; parent_event_id
结束
 

这样的话，你可以叫@ event.parent得到一个ActiveRecord事件对象和@ event.child_events获得事件对象的ActiveRecord的集合

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.

My Model:

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

My Schema:

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

解决方案

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 => "parent_event_id"
end

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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