javascript - 如何对数组对象进行分组以获得所需的数据格式？

Question

我试图使用这个对象数组对我的对象数据进行分组:

var data = [ 
    { IdUser: 8, Name: "John Smith", transferType: 'download', total: 6 },
    { IdUser: 12, Name: "Jane Smith", transferType: 'download', total: 15 },
    { IdUser: 11, Name: "Joe Smith", transferType: 'download', total: 20 },
    { IdUser: 12, Name: "Jane Smith", transferType: 'upload', total: 7 },
    { IdUser: 11, Name: "Joe Smith", transferType: 'upload', total: 16 },
    { IdUser: 8, Name: "John Smith", transferType: 'upload', total: 12 }
 ];

将所有对象的这种所需输出格式放入新数组中:

  [
    {
       IdUser: 8,
       Name: 'John Smith',
       download: [{ IdUser: 8, Name: "John Smith", transferType: 'download', total: 6}],
       upload: [{ IdUser: 8, Name: "John Smith", transferType: 'upload', total: 12 }]
    },
    { 
       IdUser: 12,
       Name: 'Jane Smith',
       donwload: [{ IdUser: 12, Name: "Jane Smith", transferType: 'download', total: 15 }],
       upload: [{ IdUser: 12, Name: "Jane Smith", transferType: 'upload', total: 7 }]
    },
    {
       IdUser: 11,
       Name: 'Joe Smith',
       download: [{ IdUser: 11, Name: "Joe Smith", transferType: 'download', total: 20 }],
       upload: [{ IdUser: 11, Name: "Joe Smith", transferType: 'upload', total: 16 }]
    }
  ];

我尝试使用 reduce 函数，但它不是我想要的格式:

data.reduce(function (a, b) {
      a[b.Name] = a[b.Name] || [];   
      a[b.Name]["IdUser"] = b.IdUser;  
      a[b.Name][b.transferType] = a[b.Name][b.transferType] || [];     
      a[b.Name][b.transferType].push(b);
      return a;
    }, []);

Answer 1

我建议你做2次。
第一次使用分组功能按 IdUser 对数据进行分组。
然后使用 for in 循环:

var data = [
  {
    "IdUser": 8,
    "Name": "John Smith",
    "transferType": "download",
    "total": 6
  },
  {
    "IdUser": 12,
    "Name": "Jane Smith",
    "transferType": "download",
    "total": 15
  },
  {
    "IdUser": 11,
    "Name": "Joe Smith",
    "transferType": "downloaded",
    "total": 20
  },
  {
    "IdUser": 12,
    "Name": "Jane Smith",
    "transferType": "upload",
    "total": 7
  },
  {
    "IdUser": 11,
    "Name": "Joe Smith",
    "transferType": "upload",
    "total": 16
  },
  {
    "IdUser": 8,
    "Name": "John Smith",
    "transferType": "upload",
    "total": 12
  }
];

var groupBy = function(xs, key) {
  return xs.reduce(function(rv, x) {
    (rv[x[key]] = rv[x[key]] || []).push(x);
    return rv;
  }, {});
};
var tmp =  groupBy(data, 'IdUser');

var formattedData = [];
for(var id in tmp ){
    formattedData.push({
    "IdUser": id,
    "Name": tmp[id][0].Name,
    "download": tmp[id].filter(obj => obj.transferType == "download"),
    "upload":tmp[id].filter(obj => obj.transferType == "upload")
    })
}
console.log(formattedData)