通过在 javascript 中保留数据（将值推送到数组中）来减少相同键值的对象数组？

Question

我有以下格式的数据，基本上是一个对象数组，我尝试了几种方法，我怎样才能更有效地做到这一点？const overdue =  [        {            "user.employeeId": "10001440",            "objectives": [                "Understand the financial indexes."            ]        },        {            "user.employeeId": "10000303",            "objectives": [                "Document preparation & writing skills"            ]        },        {            "user.employeeId": "10002168",            "objectives": [                "Chia ratio setting for Fuze Tea products L11"            ]        },        {            "user.employeeId": "10002168",            "objectives": [                "Brix parameter differences between Processing and Production of Fuze Tea Lemon-Lemongrass standardization"            ]        },        {            "user.employeeId": "10002168",            "objectives": [                "Paramix Line 9 setting parameter standardization"            ]        },    ]我如何使用 lodash 通过 JavaScript 将其转换为以下内容？[        {            "user.employeeId": "10001440",            "objectives": [                "Understand the financial indexs."            ]        },        {            "user.employeeId": "10000303",            "objectives": [                "Document preparation & writing skills"            ]        },        {            "user.employeeId": "10002168",            "objectives": [                "Brix parameter differences between Processing and Production of Fuze Tea Lemon-Lemongrass standardization",                "Paramix Line 9 setting parameter standardization",                "Chia ratio setting for Fuze Tea products L11"            ]        }    ]我试过 Array.map！和正常的逻辑，我们如何使用 lodash reduce 或 arr.reduce 更有效地做到这一点？

Answer 1

您可以使用Array.reduce来获得所需的结果，使用数组作为累加器。

我们枚举过期数组中的每个对象，如果它不存在于输出数组中，我们将其添加，否则我们将对象目标添加到输出中的相关元素。

const overdue =  [ { "user.employeeId": "10001440", "objectives": [ "Understand the financial indexes." ] }, { "user.employeeId": "10000303", "objectives": [ "Document preparation & writing skills" ] }, { "user.employeeId": "10002168", "objectives": [ "Chia ratio setting for Fuze Tea products L11" ] }, { "user.employeeId": "10002168", "objectives": [ "Brix parameter differences between Processing and Production of Fuze Tea Lemon-Lemongrass standardization" ] }, { "user.employeeId": "10002168", "objectives": [ "Paramix Line 9 setting parameter standardization" ] }, ]; 

let result = overdue.reduce((res, row) => {

    let el = res.find(el => el["user.employeeId"] === row["user.employeeId"]);

    // If we find the object in the output array simply update the objectives

    if (el) {

       el.objectives = [...el.objectives, ...row.objectives];

    } else {

    // If we _don't_ find the object, add to the output array.

      res.push({ ...row});

    }

    return res;

}, [])

console.log("Result:",result);

Answer 2

使用array.reduce对象并将其传递给累加器。在回调函数中检查累加器是否具有与 的值相同的键user.employeeId。如果不是，则创建键并将迭代中的当前对象添加为它的值。如果已经有一个键，那么只需更新目标数组。在检索值时Object.valuewhich 将给出一个数组

const overdue = [{

    "user.employeeId": "10001440",

    "objectives": [

      "Understand the financial indexes."

    ]

  },

  {

    "user.employeeId": "10000303",

    "objectives": [

      "Document preparation & writing skills"

    ]

  },

  {

    "user.employeeId": "10002168",

    "objectives": [

      "Chia ratio setting for Fuze Tea products L11"

    ]

  },

  {

    "user.employeeId": "10002168",

    "objectives": [

      "Brix parameter differences between Processing and Production of Fuze Tea Lemon-Lemongrass standardization"

    ]

  },

  {

    "user.employeeId": "10002168",

    "objectives": [

      "Paramix Line 9 setting parameter standardization"

    ]

  },

];

let newData = overdue.reduce((acc, curr) => {

  if (!acc[curr['user.employeeId']]) {

    acc[curr['user.employeeId']] = curr;

  } else {

    curr.objectives.forEach((item) => {

      acc[curr['user.employeeId']]['objectives'].push(item)

    })

  }

  return acc;

}, {});

console.log(Object.values(newData))

Answer 3

我不确定如何在 lodash 中执行此操作，但这是我仅使用 vanilla Javascript 执行此操作的方法：

const overdue = [{

    "user.employeeId": "10001440",

    "objectives": [

      "Understand the financial indexes."

    ]

  },

  {

    "user.employeeId": "10000303",

    "objectives": [

      "Document preparation & writing skills"

    ]

  },

  {

    "user.employeeId": "10002168",

    "objectives": [

      "Chia ratio setting for Fuze Tea products L11"

    ]

  },

  {

    "user.employeeId": "10002168",

    "objectives": [

      "Brix parameter differences between Processing and Production of Fuze Tea Lemon-Lemongrass standardization"

    ]

  },

  {

    "user.employeeId": "10002168",

    "objectives": [

      "Paramix Line 9 setting parameter standardization"

    ]

  },

];

const combined = {};

overdue.forEach(o => {

  const id = o["user.employeeId"];

  const obj = o["objectives"][0];

  

  if(!combined[id]) { combined[id] = [obj]; }

  else { combined[id].push(obj); }

  

});

const result = [];

Object.keys(combined).forEach(key => {

  result.push({"user.employeeId" : key, "objectives" : combined[key]});

});

console.log(result);

Answer 4

如果你可以使用 lodash，那么你就可以超越 reduce 并使用更具体的东西来满足你的需求。在这种情况下，您可以考虑使用该_.groupBy方法，该方法将创建一个由user.employeeId值作为键的对象，其中包含值作为每个对象的数组。然后，您可以将对象的值（即：具有相同 employeeId 的对象数组）映射到每个数组合并的合并对象objectives。最后，您可以获取分组对象的值以获得结果：

const overdue = [{ "user.employeeId": "10001440", "objectives": [ "Understand the financial indexes." ] }, { "user.employeeId": "10000303", "objectives": [ "Document preparation & writing skills" ] }, { "user.employeeId": "10002168", "objectives": [ "Chia ratio setting for Fuze Tea products L11" ] }, { "user.employeeId": "10002168", "objectives": [ "Brix parameter differences between Processing and Production of Fuze Tea Lemon-Lemongrass standardization" ] }, { "user.employeeId": "10002168", "objectives": [ "Paramix Line 9 setting parameter standardization" ] }, ];

const group = _.flow(

  arr => _.groupBy(arr, "user.employeeId"),

  g => _.mapValues(g, arr => _.mergeWith(...arr, (objV, srcV) => {

    if (_.isArray(objV)) return objV.concat(srcV);

  })),

  _.values

);

console.log(group(overdue));

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.15/lodash.min.js"></script>

或者您可以将 vanilla JS 与.reduce()a 一起使用Map，这使用了 JS 的更多现代功能（节点 14.0.0 均支持），例如可选链接 ?.和空合并运算符 ??：

const overdue = [{ "user.employeeId": "10001440", "objectives": [ "Understand the financial indexes." ] }, { "user.employeeId": "10000303", "objectives": [ "Document preparation & writing skills" ] }, { "user.employeeId": "10002168", "objectives": [ "Chia ratio setting for Fuze Tea products L11" ] }, { "user.employeeId": "10002168", "objectives": [ "Brix parameter differences between Processing and Production of Fuze Tea Lemon-Lemongrass standardization" ] }, { "user.employeeId": "10002168", "objectives": [ "Paramix Line 9 setting parameter standardization" ] }, ];

const group = (arr, key) => Array.from(arr.reduce((m, obj) =>

  m.set(

    obj[key], 

    {...obj, objectives: [...(m.get(obj[key])?.objectives ?? []), ...obj.objectives]}

  ), new Map).values()

);

console.log(group(overdue, "user.employeeId"));