从键值对创建对象数组

Question

从服务我收到一个带键值对的JSON对象,我需要从它们动态创建对象,按一列分组.

JSON看起来像这样:

[
    { "Group" : "A", "Key" : "Name", "Value" : "John" },
    { "Group" : "A", "Key" : "Age",  "Value" : "30" },
    { "Group" : "A", "Key" : "City", "Value" : "London" },
    { "Group" : "B", "Key" : "Name", "Value" : "Hans" },
    { "Group" : "B", "Key" : "Age",  "Value" : "35" },
    { "Group" : "B", "Key" : "City", "Value" : "Berlin" },
    { "Group" : "C", "Key" : "Name", "Value" : "José" },
    { "Group" : "C", "Key" : "Age",  "Value" : "25" },
    { "Group" : "C", "Key" : "City", "Value" : "Madrid" }
]

我需要将其转换为以下对象数组:

[
    { Group : "A", Name : "John", Age : 30, City : "London" },
    { Group : "B", Name : "Hans", Age : 35, City : "Berlin" },
    { Group : "C", Name : "José", Age : 25, City : "Madrid" }
]

每个组可以包含任意数量的键值对.

目前我有一个可行的解决方案,但我不知道它是否是最佳的:

var items = [
    { "Group" : "A", "Key" : "Name", "Value" : "John" },
    { "Group" : "A", "Key" : "Age",  "Value" : "30" },
    { "Group" : "A", "Key" : "City", "Value" : "London" },
    { "Group" : "B", "Key" : "Name", "Value" : "Hans" },
    { "Group" : "B", "Key" : "Age",  "Value" : "35" },
    { "Group" : "B", "Key" : "City", "Value" : "Berlin" },
    { "Group" : "C", "Key" : "Name", "Value" : "José" },
    { "Group" : "C", "Key" : "Age",  "Value" : "25" },
    { "Group" : "C", "Key" : "City", "Value" : "Madrid" }
], item, record, hash = {}, results = [];

// Create a "hash" object to build up
for (var i = 0, len = items.length; i < len; i += 1) {
    item = items[i];

  if (!hash[item.Group]) {
    hash[item.Group] = {
      Group : item.Group
    };
  }
  hash[item.Group][item.Key] = item.Value;
}

// Push each item in the hash to the array
for (record in hash) {
  if(hash.hasOwnProperty(record)) {
    results.push(hash[record]);
  }
}

你可以在这里查看小提琴:http://jsbin.com/ozizom/1/

你有更好的解决方案吗？

Answer 1

假设JSON记录将始终按Group排序,这是另一种方法:

var json = [
    { "Group" : "A", "Key" : "Name", "Value" : "John" },
    { "Group" : "A", "Key" : "Age",  "Value" : "30" },
    { "Group" : "A", "Key" : "City", "Value" : "London" },
    { "Group" : "B", "Key" : "Name", "Value" : "Hans" },
    { "Group" : "B", "Key" : "Age",  "Value" : "35" },
    { "Group" : "B", "Key" : "City", "Value" : "Berlin" },
    { "Group" : "C", "Key" : "Name", "Value" : "José" },
    { "Group" : "C", "Key" : "Age",  "Value" : "25" },
    { "Group" : "C", "Key" : "City", "Value" : "Madrid" }
];

var array = [];
var previousGroup = null;

for(var i=0; i<json.length; i++) {
    var group = json[i].Group;
    if(previousGroup != group) {
        array.push({Group: group});
        previousGroup = group;
    }
    array[array.length-1][json[i].Key] = json[i].Value;
}

这是一个有效的例子.