具有主干关系的主干JS嵌套模型

Question

我正在尝试实现具有骨干关系的骨干。

声明模型：

define(['underscore', 'backbone', 'backbone-relational', 'models/User'], function(_, Backbone, relational, User) {
  var Claim = Backbone.RelationalModel.extend({
  relations: [{
      type: Backbone.HasOne,
      key: 'a_user',
      relatedModel: User
  }],
  defaults: {
  },
  initialize: function() {
  },
  clear: function() {
    this.destroy();
    this.view.remove();
  }
  });
  return Claim;
});

用户模型是重复的，但未设置任何关系。

下面是集合对象：

Object
_byCid: Object
_byId: Object
_callbacks: Object
currentPage: 1
firstPage: 1
information: Object
length: 3
models: Array[3]
0: Object
1: Object
    _callbacks: Object
    _deferProcessing: false
    _escapedAttributes: Object
    _isInitialized: true
    _pending: Object
    _permitsUsed: 0
    _previousAttributes: Object
    _queue: Object
    _relations: Array[1]
    _silent: Object
    attributes: Object
       _deleted: false
       _new: false
       a_user: Object
           _callbacks: Object
           _escapedAttributes: Object
           _isInitialized: true
           _pending: Object
           _permitsUsed: 0
           _previousAttributes: Object
           _queue: Object
           _relations: Array[0]
           _silent: Object
           attributes: Object
               _deleted: false
               _new: false
               already_in_save: false
               already_in_validation: false
               coll_claims: Array[0]
               coll_claims_partial: true
               created_at: "2012-12-12 09:00:00"
               email: "[e-mail]"
               firstname: "Cloud"
               id: 2
               lastname: "Strife"
               modified_at: "2012-12-12 09:00:00"
               modified_columns: Array[0]
               start_copy: false
               title: "Mr"
               validation_failures: Array[0]
               virtual_columns: Array[0]
               __proto__: Object
               changed: Object
               cid: "c4"
               collection: undefined
               id: 2
               __proto__: Object
               already_in_save: false
               already_in_validation: false
      created_at: "2012-12-12 09:00:00"
      fulfilment: "bank"
      id: 2
      manual: 0
      modified_at: "2012-12-12 09:00:00"
      modified_columns: Array[0]
      promotion_id: 1
      purchase_id: 2
      start_copy: false
      status: "pending"
      user_id: 2
      validation_failures: Array[0]
      virtual_columns: Array[0]
      __proto__: Object
      changed: Object
      cid: "c3"
  collection: Object
  id: 2
  __proto__: Object
  2: Object
  length: 3

因此，实质上集合中有 3 个声明模型，每个声明模型在属性键a_user都有一个嵌套的 User 模型。

模板如下所示：

<% _.each( claims, function( item ){ %>
    <tr>
        <td><%= item.get("id") %></td>
        <td><%= item.get("promotion_id") %></td>
        <td><%= item.get("a_user").get("firstname") %></td>
        <td><%= item.get("purchase_id") %></td>
    <td></td>
        <td><%= item.get("status") %></td>
        <td><%= item.get("created_at") %></td>
    </tr>
<% }); %>

但是，这会导致错误：

TypeError: 'null' is not an object (evaluating 'item.get("a_user").get')

如果我把它带回 item.get（"a_user"），它会显示输出 [对象对象]

我只是在学习骨干，所以任何指示都值得赞赏。

Answer 1

您不应该在模板中使用get - 下划线模板适用于 JSON，而不是 Backbone 模型对象（您使用 template(model.toJSON()) 将模型传递给模板），因此应使用基本的点表示法来评估它们：

<tr>
    <td><%= item.id %></td>
    <td><%= item.promotion_id %></td>
</tr>