有人知道一种方法(lodash如果可能的话)通过对象键分组对象数组,然后根据分组创建一个新的对象数组吗?例如,我有一个汽车对象数组:

const cars = [
    {
        'make': 'audi',
        'model': 'r8',
        'year': '2012'
    }, {
        'make': 'audi',
        'model': 'rs5',
        'year': '2013'
    }, {
        'make': 'ford',
        'model': 'mustang',
        'year': '2012'
    }, {
        'make': 'ford',
        'model': 'fusion',
        'year': '2015'
    }, {
        'make': 'kia',
        'model': 'optima',
        'year': '2012'
    },
];

我想创建一个新的汽车对象数组,由make分组:

const cars = {
    'audi': [
        {
            'model': 'r8',
            'year': '2012'
        }, {
            'model': 'rs5',
            'year': '2013'
        },
    ],

    'ford': [
        {
            'model': 'mustang',
            'year': '2012'
        }, {
            'model': 'fusion',
            'year': '2015'
        }
    ],

    'kia': [
        {
            'model': 'optima',
            'year': '2012'
        }
    ]
}

当前回答

添加Array.prototype.group和Array.prototype.groupToMap的提案现在处于阶段3!

当它达到阶段4并在大多数主流浏览器上实现时,你将能够这样做:

const cars = [
  { make: 'audi', model: 'r8', year: '2012' },
  { make: 'audi', model: 'rs5', year: '2013' },
  { make: 'ford', model: 'mustang', year: '2012' },
  { make: 'ford', model: 'fusion', year: '2015' },
  { make: 'kia', model: 'optima', year: '2012' }
];

const grouped = cars.group(item => item.make);
console.log(grouped);

这将输出:

{
  audi: [
    { make: 'audi', model: 'r8', year: '2012' },
    { make: 'audi', model: 'rs5', year: '2013' }
  ],
  ford: [
    { make: 'ford', model: 'mustang', year: '2012' },
    { make: 'ford', model: 'fusion', year: '2015' }
  ],
  kia: [
    { make: 'kia', model: 'optima', year: '2012' }
  ]
}

在那之前,你可以使用这个core-js polyfill:

const cars = [ { make: 'audi', model: 'r8', year: '2012' }, { make: 'audi', model: 'rs5', year: '2013' }, { make: 'ford', model: 'mustang', year: '2012' }, { make: 'ford', model: 'fusion', year: '2015' }, { make: 'kia', model: 'optima', year: '2012' } ]; const grouped = cars.group(item => item.make); //console.log(grouped); // Optional: remove the "make" property from resulting object const entriesUpdated = Object .entries(grouped) .map(([key, value]) => [ key, value.map(({make, ...rest}) => rest) ]); const noMake = Object.fromEntries(entriesUpdated); console.log(noMake); <script src="https://unpkg.com/core-js-bundle@3.26.1/minified.js"></script>

其他回答

您可以尝试在调用per iteration的函数中修改对象_。groupBy func。 注意,源数组改变了它的元素!

var res = _.groupBy(cars,(car)=>{
    const makeValue=car.make;
    delete car.make;
    return makeValue;
})
console.log(res);
console.log(cars);

创建一个可以重用的方法

Array.prototype.groupBy = function(prop) {
      return this.reduce(function(groups, item) {
        const val = item[prop]
        groups[val] = groups[val] || []
        groups[val].push(item)
        return groups
      }, {})
    };

下面你可以根据任何标准进行分组

const groupByMake = cars.groupBy('make');
        console.log(groupByMake);

var cars = [ { 'make': 'audi', 'model': 'r8', 'year': '2012' }, { 'make': 'audi', 'model': 'rs5', 'year': '2013' }, { 'make': 'ford', 'model': 'mustang', 'year': '2012' }, { 'make': 'ford', 'model': 'fusion', 'year': '2015' }, { 'make': 'kia', 'model': 'optima', 'year': '2012' }, ]; //re-usable method Array.prototype.groupBy = function(prop) { return this.reduce(function(groups, item) { const val = item[prop] groups[val] = groups[val] || [] groups[val].push(item) return groups }, {}) }; // initiate your groupBy. Notice the recordset Cars and the field Make.... const groupByMake = cars.groupBy('make'); console.log(groupByMake); //At this point we have objects. You can use Object.keys to return an array

这是一个通用函数,将返回Array groupBy自己的键。

const getSectionListGroupedByKey = < T > ( property: keyof T, List: Array < T > ): Array < { title: T[keyof T];data: Array < T > } > => { const sectionList: Array < { title: T[keyof T];data: Array < T > } > = []; if (!property || !List ? .[0] ? .[property]) { return []; } const groupedTxnListMap: Map < T[keyof T], Array < T >> = List.reduce((acc, cv) => { const keyValue: T[keyof T] = cv[property]; if (acc.has(keyValue)) { acc.get(keyValue) ? .push(cv); } else { acc.set(keyValue, [cv]); } return acc; }, new Map < T[keyof T], Array < T >> ()); groupedTxnListMap.forEach((value, key) => { sectionList.push({ title: key, data: value }); }); return sectionList; }; // Example const cars = [{ 'make': 'audi', 'model': 'r8', 'year': '2012' }, { 'make': 'audi', 'model': 'rs5', 'year': '2013' }, { 'make': 'ford', 'model': 'mustang', 'year': '2012' }, { 'make': 'ford', 'model': 'fusion', 'year': '2015' }, { 'make': 'kia', 'model': 'optima', 'year': '2012' }, ]; const result = getSectionListGroupedByKey('make', cars); console.log('result: ', result)

我喜欢@metakunfu的答案,但它并没有提供预期的输出。 下面是在最终的JSON有效负载中去除“make”的更新。

var cars = [
    {
        'make': 'audi',
        'model': 'r8',
        'year': '2012'
    }, {
        'make': 'audi',
        'model': 'rs5',
        'year': '2013'
    }, {
        'make': 'ford',
        'model': 'mustang',
        'year': '2012'
    }, {
        'make': 'ford',
        'model': 'fusion',
        'year': '2015'
    }, {
        'make': 'kia',
        'model': 'optima',
        'year': '2012'
    },
];

result = cars.reduce((h, car) => Object.assign(h, { [car.make]:( h[car.make] || [] ).concat({model: car.model, year: car.year}) }), {})

console.log(JSON.stringify(result));

输出:

{  
   "audi":[  
      {  
         "model":"r8",
         "year":"2012"
      },
      {  
         "model":"rs5",
         "year":"2013"
      }
   ],
   "ford":[  
      {  
         "model":"mustang",
         "year":"2012"
      },
      {  
         "model":"fusion",
         "year":"2015"
      }
   ],
   "kia":[  
      {  
         "model":"optima",
         "year":"2012"
      }
   ]
}

提莫的答案是我会怎么做。简单的_。groupBy,并允许在分组结构中的对象中有一些重复。

然而,OP还要求删除重复的make键。如果你想从头到尾:

var grouped = _.mapValues(_.groupBy(cars, 'make'),
                          clist => clist.map(car => _.omit(car, 'make')));

console.log(grouped);

收益率:

{ audi:
   [ { model: 'r8', year: '2012' },
     { model: 'rs5', year: '2013' } ],
  ford:
   [ { model: 'mustang', year: '2012' },
     { model: 'fusion', year: '2015' } ],
  kia: 
   [ { model: 'optima', year: '2012' } ] 
}

如果你想使用Underscore.js来实现这个功能,请注意它的_. js版本。mapValues被称为_.mapObject。