如果我在 Rails 中有以下模型,我将如何在 Ember/Ember Data 中表示它?
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
我找到的引用文献是 the relevant ember-data pull request , the ember-data tests for polymorphic relationships , 和 this related question但是很难从它们中找出一个典型的例子。
最佳答案
我现在使用两种不同的方式来处理 Rails 风格的“多态”模型。我已经更新了下面的代码以显示这两种用途。
Attachment
型号 :这在 Rails 端是“多态的”,但在 Ember 端总是“嵌入”的。这样做的原因是我目前只需要保存/更新附件及其关联模型。
Comment
型号 :这在 Rails 端和 Ember 端都是多态的。
我还包含了 Post
的代码模型,因为它可以有多个附件和多个评论。
导轨代码:
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, :body, :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
Ember 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 代码在尝试发回模型上定义的所有属性时,已经被 ember-data 特定的奇怪东西污染了。 ( 注意 :有一个 open proposal 用于解决参数污染问题的只读属性)
如果有人知道处理上述任何一项的更好方法,请告诉我!
注意:我有点担心模型从
App.Commentable
扩展将阻止我在模型上拥有多个多态附件,我可能需要寻找不同的处理方式。
关于ember.js - ember-data 中 Rails 风格的多态模型,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/16561173/