如果我在Rails中有以下模型,我将如何在Ember / Ember数据中表示这个？
class Attachment < ActiveRecord::Base belongs_to :user belongs_to :attachable,polymorphic: true end class Profile < ActiveRecord::Base belongs_to :user has_one :photo,class_name: 'Attachment',as: :attachable end class Post < ActiveRecord::Base belongs_to :user has_many :attachments,as: :attachable end
我发现的参考文献是the relevant ember-data pull request,the ember-data tests for polymorphic relationships和this related question,但很难从它们中找出一个典型的例子.
解决方法
我现在使用两种不同的方式使用rails风格的“多态”模型.我已更新下面的代码以显示两种用途.
附件模型：这是Rails端的“多态”,但总是“嵌入”在Ember端.原因是我目前只需要保存/更新附件及其相关模型.
评论模型：这在Rails方面和Ember方面都是多态的.
我还为Post模型添加了代码,因为它可以有多个附件和多个注释.
Rails代码：
class Attachment < ActiveRecord::Base
belongs_to :user
belongs_to :attachable,polymorphic: true
end
class Comment < ActiveRecord::Base
belongs_to :user
belongs_to :commentable,polymorphic: true
end
class Post < ActiveRecord::Base
belongs_to :user
has_many :attachments,as: :attachable
has_many :comments,as: :commentable
end
class ApplicationSerializer < ActiveModel::Serializer
embed :ids,include: true
end
class AttachmentSerializer < ApplicationSerializer
attributes :id,:url,:errors
has_many :comments
end
class CommentSerializer < ApplicationSerializer
attributes :id,:body,:created_at,:commentable_id,:commentable_type
has_one :user
end
class PostSerializer < ApplicationSerializer
attributes :id,:title,:posted_at,:errors
has_one :user
has_many :attachments,embed: :objects,include: true
has_many :comments
end
class Api::V1::PostsController < Api::V1::BaseController
before_filter :auth_only!,only: :create
def create
# clean / capture ember-data supplied arguments
params[:post].delete(:user_id)
attachments_params = params[:post].delete(:attachments)
@post = current_user.posts.new(params[:post])
process_attachments(attachments_params)
if @post.save
render json: @post,status: 201
else
warden.custom_failure!
render json: @post,status: 422
end
end
protected
def process_attachments(attachments_params)
return unless attachments_params.present?
attachments_params.each do |attachment_params|
# ignore ember-data's additional keys
attachment_params.delete(:created_at)
attachment_params.delete(:user_id)
attachment = @post.attachments.new(attachment_params)
attachment.user = current_user
end
end
end
灰烬代码：
DS.RESTAdapter.configure 'App.Post',alias: 'Post'
DS.RESTAdapter.map 'App.Post',attachments: { embedded: 'always' }
App.Store = DS.Store.extend
adapter: DS.RESTAdapter.create
namespace: 'api/v1'
App.Comment = App.Model.extend
user: DS.belongsTo('App.User')
commentable: DS.belongsTo('App.Commentable',{ polymorphic: true })
body: DS.attr('string')
createdAt: DS.attr('date')
App.Commentable = App.Model.extend
comments: DS.hasMany('App.Comment')
App.Attachment = App.Commentable.extend
user: DS.belongsTo('App.User')
url: DS.attr('string')
App.Post = App.Commentable.extend
user: DS.belongsTo('App.User')
attachments: DS.hasMany('App.Attachment')
title: DS.attr('string')
body: DS.attr('string')
postedAt: DS.attr('date')
App.PostFormOverlayController = App.OverlayController.extend
# 'files' attribute is set by a widget that wraps the filepicker.io JS
updateAttachments: (->
attachments = @get('attachments')
attachments.clear()
@get('files').forEach (file) =>
attachment = App.Attachment.createRecord({fpFile: file})
attachments.addObject(attachment)
).observes('files')
App.CommentNewController = App.ObjectController.extend
# this should be instantiated with it's model set to the commentable
# item. eg. `{{render 'comment/new' content}}`
save: ->
transaction = @get('store').transaction()
comment = transaction.createRecord App.Comment,body: @get('body')
commentable: @get('model')
comment.one 'didCreate',@,->
@set('body',null)
transaction.commit()
不幸的是,我的Rails代码变得有点污染了特定于ember数据的怪异,因为它试图发送回模型上定义的所有属性. (注意：有一个open proposal的只读属性可以解决params污染问题)
如果有人知道更好的方法来接近上述任何一种,请告诉我！
注意：我有点担心从App.Commentable扩展模型会阻止我在模型上有多个多态附件,我可能需要寻找一种不同的处理方式.
