按数据类型自定义 KnockOut 映射答案

【问题标题】：Customizing KnockOut Mapping by data type按数据类型自定义 KnockOut 映射
【发布时间】：2018-08-23 12:09:15
【问题描述】：

我有一个看起来像这样的数据列表：

 "containers": [{
      "Id": 1,
      "Description": "B",
      "Properties": {}
},
 {
      "Id": 2,
      "Description": "A",
      "Properties": {}
},
 {
      "Id": 3,
      "Description": "B",
      "Properties": {}
},
 {
      "Id": 4,
      "Description": "A",
      "Properties": {}
}, 
 {
      "Id": 5,
      "Description": "C",
      "Properties": {}
}]

使用敲除和敲除映射插件，我的目标是创建自定义映射以创建类似：

 "containers": [{
    "A":[{
          "Id": 2,
          "Description": "A",
          "Properties": {}
        },
        {
          "Id": 4,
          "Description": "A",
          "Properties": {}
        }],
    "B":[{
          "Id": 1,
          "Description": "B",
          "Properties": {}
        },
        {
      "Id": 3,
      "Description": "B",
      "Properties": {}
        }], 
    "C"{
      "Id": 1,
      "Description": "C",
      "Properties": {}
    }]]

对象根据其描述分组为数组。

我尝试过这样的事情：

var mapping = {
    create: function (options) {
        var arrdata = [];
        if (!(options.data.Description in arrdata)) {
            arrdata[options.data.Description] = [];
        }
        arrdata[options.data.Description].push(ko.mapping.fromJS(options.data));
        return arrdata;

    }
}

但它只是它自己的数组中的每个对象，所以不是我在示例中期望的三个数组，而是 5 个数组，每个数组的大小为 1。如何告诉 Knockout Mapping 合并数组或创建完成此操作的映射？

【问题讨论】：

标签： javascript knockout.js knockout-mapping-plugin

【解决方案1】：

var containers = [{
      "Id": 1,
      "Description": "B",
      "Properties": {}
},
 {
      "Id": 2,
      "Description": "A",
      "Properties": {}
},
 {
      "Id": 3,
      "Description": "B",
      "Properties": {}
},
 {
      "Id": 4,
      "Description": "A",
      "Properties": {}
}, 
 {
      "Id": 5,
      "Description": "C",
      "Properties": {}
}]

//Remap array of objects to object with arrays of objects
groupedByDescription = {};

containers.forEach(function(c){
  //Create object properties based on container description, and create array / push to array
  if(groupedByDescription.hasOwnProperty(c.Description)){
    groupedByDescription[c.Description].push(c);
  }else{
    groupedByDescription[c.Description] = [c];
  }
});

console.log(groupedByDescription);

JS 小提琴： https://jsfiddle.net/b7g7s5h9/9/

这对您有帮助吗？应该得到你要求的结果，但不使用 ko 映射。

【讨论】：