Question

从下面的数组开始，在JavaScript中，使用Lodash，如何按唯一用户对任务进行分组，以在下面输出“ tasks_by_user”数组？

输入：

tasks: [
  {
    name: "buy milk",
    users: [
      "123", "456"
    ]
  },
  {
    name: "get bread",
    users: [
      "123"
    ]
  }
]

输出：

tasks_by_user : [
  {
    user: "123",
    tasks: [
      {
        name: "buy milk"
      },
      {
        name: "get bread"
      }
    ]
  },
  {
    user: "456",
    tasks: [
      {
        name: "buy milk"
      }
    ]
  }
]

Answer 1

您可以使用reduce和forEach方法进行操作。

const data = [{"name":"buy milk","users":["123","456"]},{"name":"get bread","users":["123"]}]

let result = _.values(_.reduce(data, (r, {name,users}) => {
  _.forEach(users, user => {
    if (!r[user]) r[user] = {
      user,
      tasks: []
    }
    r[user].tasks.push({name})
  })
  return r;
}, {}))

console.log(result)

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.10/lodash.js"></script>

Answer 2

普通的javascript解决方案。

const data = [{
  "name": "buy milk",
  "users": ["123", "456"]
}, {
  "name": "get bread",
  "users": ["123"]
}];

var result = data.reduce((acc, {name, users}) => {
  users.forEach(u => {
    acc[u] = (acc[u] || []);
    acc[u].push(name);
  });
  return acc;
}, {});
console.log(Object.getOwnPropertyNames(result).map(user => {
  return {
    user,
    tasks: result[user]
  };
}));

Answer 3

您可以使用本机Array.prototype.reduce通过按用户ID对输入数据进行分组，然后将分组后的对象映射到数组来完成此操作：

const tasks=[{name:"buy milk",users:["123","456"]},{name:"get bread",users:["123"]}];

var dataObj = tasks.reduce((all, {name, users}) => {

  users.forEach(user => {

    if (!all.hasOwnProperty(user)) all[user] = {user, tasks: []};

    all[user].tasks.push({name});

  })

  return all;

}, {});

var tasks_by_user = Object.keys(dataObj).map(k => dataObj[k]);

console.log(tasks_by_user);

Answer 4

@trs ，您也可以尝试以下代码。

/* Input array */
var tasks = {tasks: [
  {
    name: "buy milk",
    users: [
      "123", "456"
    ]
  },
  {
    name: "get bread",
    users: [
      "123"
    ]
  }
]}

var inputArr = tasks['tasks']

/* Creating output array */
var outputArr = []
var outputObj = {}

for(var obj of inputArr){
    for(var user of obj["users"]){
        var o = {'name': obj['name']}

        if(outputObj[user] == undefined){
            outputObj[user] = [o]
        } else {
            outputObj[user].push(o)
        }
    }
}

console.log(JSON.stringify(outputObj, null, 4))
/*
    {
        "123": [
            {
                "name": "buy milk"
            },
            {
                "name": "get bread"
            }
        ],
        "456": [
            {
                "name": "buy milk"
            }
        ]
    }
*/

for(var key in outputObj) {
    outputArr.push({'user': key, 'tasks': outputObj[key]})
}

console.log(JSON.stringify(outputArr, null, 4))
/*
    [
        {
            "user": "123",
            "tasks": [
                {
                    "name": "buy milk"
                },
                {
                    "name": "get bread"
                }
            ]
        },
        {
            "user": "456",
            "tasks": [
                {
                    "name": "buy milk"
                }
            ]
        }
    ]
*/

最终输出：

[
    {
        "user": "123",
        "tasks": [
            {
                "name": "buy milk"
            },
            {
                "name": "get bread"
            }
        ]
    },
    {
        "user": "456",
        "tasks": [
            {
                "name": "buy milk"
            }
        ]
    }
]

通过嵌套数组的唯一值对数组进行分组

4 个答案: