Ember.js 分组结果

Question

我正在尝试在 Ember.js 中实现“分组依据”功能，事实证明它比我最初想象的要困难。

[{date: '2014-01-15T16:22:16-08:00', message: 'Tidal wave occurred'},
{date: '2014-01-15T05:00:16-08:00', message: 'Tornado destroyed town'},
{date: '2014-01-13T14:22:16-08:00', message: 'Volcanic eruption, likely'},
{date: '2014-01-13T16:24:16-08:00', message: 'Ice shelf calving off completely'},
{date: '2014-01-11T11:27:26-08:00', message: 'Mother-in-law visiting'}]

我正在寻找与此类似的最终输出:

Today
----------
4:22 pm - Tidal wave occurred
5:00 am - Tornado destroyed town

Monday
----------
2:22 pm - Volcanic eruption, likely
...etc., etc.

现在该数据已绑定(bind)到 ArrayController。每个对象都有一个计算属性，用于获取“年/月/日”进行分组比较。

var ActivityController = Em.ArrayController.extend({

    groupedResults: function () {
        var result = [];

        //Iterate over each item in the list, but do what with it?
        this.get('content').filter(function (item) {

        });

        return result;
    }.property('content.[]')

});

关于实现这一点的最佳方法有什么建议吗？ Ember 附带了filterBy 和mapBy，但没有groupBy。

Answer 1

这是我稍作修改的可分组实现:

Groupable = Ember.Mixin.create
  group: null
  ungroupedContent: null

  groupedContent: (->
    model = @
    groupedContent = Ember.A([])

    groupCallback = @get('group')
    ungroupedContent = @get('ungroupedContent')

    return groupedContent unless groupCallback
    return groupedContent unless ungroupedContent

    ungroupedContent.forEach (item) ->
      group = groupCallback.call(model, item)
      return unless groupKey = group.get('key')

      foundGroup = groupedContent.findProperty('group.key', groupKey)

      unless foundGroup
        foundGroup = groupedContent.pushObject Ember.ArrayProxy.create
          group: group,
          content: Ember.A([])

      foundGroup.get('content').pushObject(item)

    groupedContent
  ).property('group', 'ungroupedContent.@each')

Controller 使用:

ActivitiesController = Ember.ArrayController.extend Groupable,
  ungroupedContentBinding: 'content' # tell Groupable where your default content is

  # the callback that will be called for every
  # item in your content array -
  # just return the same 'key' to put it in the same group
  group: (activity) ->
    Ember.Object.create
      key: moment.utc(activity.get('date')).format('YYYY-MM-DD') # using momentjs to pluck the day from the date
      description: 'some string describing this group (if you want)'

模板用法:

{{#each groupedContent}}
  {{group.key}} - {{group.description}}

  {{#each content}}
    Here's the really bad thing that happened: {{message}}
  {{/each}}
{{/each}}

本质上，Groupable mixin 所做的就是循环遍历普通内容 ArrayProxy 并调用一个函数来确定它属于哪个组。如果该组对象尚不存在(即未找到匹配的group.key)，则会在将当前内容项添加到组内容之前创建该对象。 p>

因此，您在模板中最终得到的是对象 (Ember.Object) 的新数组 (ArrayProxy)，每个对象都有一个组 属性(必须至少有一个 key 属性来标识它)和一个 content 属性(包含属于该组的内容)。