Question

在我的nodeJs代码中，我从数据库中获取一些记录。我将数据作为JSON获取如下：

"Data": [{
    "id": 1,
    "color": "blue",
    "model_name": "ford",
    "year": 2016
}, {
    "id": 2,
    "color": "blue",
    "model_name": "Maruti",
    "year": 2016
}, {
    "id": 3,
    "color": "red",
    "model_name": "Fiat",
    "year": 2016
}, {
    "id": 4,
    "color": "red",
    "model_name": "tata",
    "year": 2016
}]

我想要的是类似下面的JSON：

"Data": [{
    "color": "blue",
    car: [{
        "id": 1,
        "color": "blue",
        "model_name": "ford",
        "year": 2016
    }, {
        "id": 2,
        "color": "blue",
        "model_name": "Maruti",
        "year": 2016
    }]
}, {
    "color": "red",
    car: [{
        "id": 3,
        "color": "red",
        "model_name": "Fiat",
        "year": 2016
    }, {
        "id": 4,
        "color": "red",
        "model_name": "tata",
        "year": 2016
    }]
}]

我可以使用以下代码使用下划线JS的'groupBy'方法实现此目的：

var groupedData = _.groupBy(rows, f=>{return f.color});

然而输出变为：

"Data": [{
    "blue": [{
        "id": 1,
        "color": "blue",
        "model_name": "ford",
        "year": 2016
    }, {
        "id": 2,
        "color": "blue",
        "model_name": "Maruti",
        "year": 2016
    }]
}, {

    "red": [{
        "id": 3,
        "color": "red",
        "model_name": "Fiat",
        "year": 2016
    }, {
        "id": 4,
        "color": "red",
        "model_name": "tata",
        "year": 2016
    }]
}]

问题在于颜色名称本身就是关键。我想要这种格式的“颜色”：“蓝色”，但是在一组中。

Answer 1

在这里，我做了一个小groupBy函数，适用于你的情况。为了保持通用性，我更换了汽车＆＃34;关键名称＆＃34; items＆＃34; ：

function groupBy(key, array) {
  var result = [];
  for (var i = 0; i < array.length; i++) {
    var added = false;
    for (var j = 0; j < result.length; j++) {
      if (result[j][key] == array[i][key]) {
        result[j].items.push(array[i]);
        added = true;
        break;
      }
    }
    if (!added) {
      var entry = {items: []};
      entry[key] = array[i][key];
      entry.items.push(array[i]);
      result.push(entry);
    }
  }
  return result;
}

现在如果

var data = [{
    "id": 1,
    "color": "blue",
    "model_name": "ford",
    "year": 2016
}, {
    "id": 2,
    "color": "blue",
    "model_name": "Maruti",
    "year": 2016
}, {
    "id": 3,
    "color": "red",
    "model_name": "Fiat",
    "year": 2016
}, {
    "id": 4,
    "color": "red",
    "model_name": "tata",
    "year": 2016
}]

然后

groupBy("color", data);

应该给你预期的结果：

[
  {
    "color": "blue",
    "items": [
      {
        "id": 1,
        "color": "blue",
        "model_name": "ford",
        "year": 2016
      },
      {
        "id": 2,
        "color": "blue",
        "model_name": "Maruti",
        "year": 2016
      }
    ]
  },
  {
    "color": "red",
    "items": [
      {
        "id": 3,
        "color": "red",
        "model_name": "Fiat",
        "year": 2016
      },
      {
        "id": 4,
        "color": "red",
        "model_name": "tata",
        "year": 2016
      }
    ]
  }
]

Answer 2

以下是使用lodash的简短回答：

...where now() between start_date and iif( end_date IS NULL, #2099-12-31 23:59:59#, end_date )

如果您发现令人困惑，可以将其视为：

_(Data)
    .groupBy((elem) => elem.color)
    .map((vals, key) => ({color: key, car: vals}))
    .value()

希望这有帮助。

Answer 3

const data = [
{
  "id": 1,
  "color": "blue",
  "model_name": "ford",
  "year": 2016
},
{
  "id": 2,
  "color": "blue",
  "model_name": "Maruti",
  "year": 2016
},
{
  "id": 3,
  "color": "red",
  "model_name": "Fiat",
  "year": 2016
},
{
  "id": 4,
  "color": "red",
  "model_name": "tata",
  "year": 2016
}
];

const sorted = data.reduce((result, car) => {
    const a = result.find(({color}) => color === car.color);
    a ? a.car.push(car) : result.push({color: car.color, car: [car]});
    return result;
}, []);

console.log(sorted);

Answer 4

纯ES6代码的另一种直接方式。

＆＃13;

var data = [
{
  "id": 1,
  "color": "blue",
  "model_name": "ford",
  "year": 2016
},
{
  "id": 2,
  "color": "blue",
  "model_name": "Maruti",
  "year": 2016
},
{
  "id": 3,
  "color": "red",
  "model_name": "Fiat",
  "year": 2016
},
{
  "id": 4,
  "color": "red",
  "model_name": "tata",
  "year": 2016
}],
    hash = data.reduce((p,c) => (p[c.color] ? p[c.color].push(c) : p[c.color] = [c],p) ,{}),
 newData = Object.keys(hash).map(k => ({color: k, car: hash[k]}));
console.log(newData);

＆＃13;

在Node中按JSON数据分组

4 个答案: