更改/定义多对多关系的保存端答案

【问题标题】：Change/Define the saving end of a many-to-many relationship更改/定义多对多关系的保存端
【发布时间】：2013-09-14 19:36:05
【问题描述】：

我的应用程序中的用户和对话之间存在多对多关系

App.User = DS.Model.extend,
  conversations: DS.hasMany('App.Conversation')    

App.Conversation = DS.Model.extend
  participants: DS.hasMany('App.User')

但每次我创建和保存对话时，ember 都会尝试保存每个参与者，包括他们相关对话的 ID。但我想要完全相反，我希望它只更新一个对话并发送相关的参与者 ID。

有没有办法让它发挥作用？

到目前为止我尝试了什么：

在用户模型上指定逆键 (conversations: DS.hasMany('App.Conversation', inverse: 'participants'))
下面的解决方法。

App.RESTAdapter = DS.RESTAdapter.extend

  serializer: DS.RESTSerializer.extend
    addHasMany: (hash, record, key, relationship) ->
      type = record.constructor
      name = relationship.key
      serializedHasMany = []

      embeddedType = this.embeddedType(type, name)
      return unless embeddedType is 'always'

      record.get(name).forEach (record) ->
        serializedHasMany.push record.get('id')
      , @

      hash[@singularize(key) + '_ids'] = serializedHasMany

App.RESTAdapter.map 'D4S.Conversation',
  participants:
    embedded: 'always'

之后它将保存包括外键在内的对话，但仍会尝试更新用户，因此我尝试使用自定义请求保存它并重置参与者状态：/

    App.Conversation._createWith = (participants) ->
      conversation = @createRecord()

      participants.forEach (p) ->
        conversation.get('participants').addObject(p)

      # conversation.save()
      adapter = conversation.get('store._adapter')
      adapter.ajax(adapter.buildURL('conversation'), 'POST',
        data: { conversation: conversation.serialize() }
      ).then ->
        conversation.setProperties(arguments[0].conversation)
        conversation.get('stateManager').transitionTo('saved')
        conversation.get('participants').forEach (user) ->
          user.get('stateManager').transitionTo('saved')
        conversation.trigger('didCommit')

      conversation

这终于奏效了 \o/ 但是抛出了下一个错误:(

加载 ember 时不会加载关系，会话参与者属性始终为空 DS.ManyArray

那么有没有办法让它发挥作用？

【问题讨论】：

标签： ember.js foreign-keys many-to-many ember-data relationship

【解决方案1】：

解决方案：实现自己的映射键，不要使用已经使用过的键。这个实现解决了我所有的问题：

serializer: DS.RESTSerializer.extend
  ###
  Custom implementation to realize manySaving mapping
  ###
  addHasMany: (hash, record, key, relationship) ->
    @_super(hash, record, key, relationship)
    type = record.constructor
    name = relationship.key
    serializedHasMany = []

    manySaving = this.manySaving(type, name)
    return unless manySaving

    record.get(name).forEach (record) ->
      serializedHasMany.push record.get('id')
    , @

    hash[key] = serializedHasMany

  ###
  Check if manySaving option for a specific relationship is enabeld
  @param {String} type  The record type (usally a model class)
  @param {String} name  The attribute name of the relationship
  @return {Boolean}
  ###
  manySaving: (type, name) ->
    this.mappingOption(type, name, 'manySaving')

D4S.RESTAdapter.map 'D4S.User',
  conversations:
    manySaving: false

D4S.RESTAdapter.map 'D4S.Conversation',
  participants:
    manySaving: true
    key: 'participant_ids'

【讨论】：