Question

我有一个群体对象：

{groupid1: "metadata",
 groupid2: "metadata"}

以及一系列用户：

[
 {
  name: "something",
  groups: ["groupid1", "groupid2"]
  ...},
 {
  name: "something else ",
  groups: ["groupid1"]
  ...},
 {
  name: "something else again",
  groups: ["groupid2"]
  ...},
]

我想迭代组ID并提取与该组ID匹配的用户列表，因此我最终记录了两个用户列表，每组一个：

for (group in groups) {
 var userArray = _.pluck(users, function(user) { 
  return user.groups.indexOf(group) > -1;
 })
 console.log(userArray);
}

问题是这会返回一个未定义的数组，而不是一组用户对象。即使只是返回用户的名字也不错。

感谢您提供任何帮助！对于可伸缩性，下划线是解决此问题的首选方法。

Answer 1

正如docs _.pluck()中所述，有两个参数：列表和属性名称 - 您不提供属性名称而是提供函数。更重要的是，这不是您使用_.pluck()函数的原因（再次查看文档）。

在您的情况下，您根本不需要使用UnderscoreJS：

＆＃13;

// Your groups
const groups = {
  groupid1: "metadata",
  groupid2: "metadata"
};

// Your users
const users = [
 {
  name: "something",
  groups: ["groupid1", "groupid2"],
 },
 {
  name: "something else ",
  groups: ["groupid1"]
 },
 {
  name: "something else again",
  groups: ["groupid2"]
 }
];

// Get ids of the groups and loop through them
const result = Object.keys(groups).forEach(groupId => {
  // Return only users whose groups array contains the groupId
  const usersFound = users.filter(user => user.groups.indexOf(groupId) > -1);
  
  // Log the users found
  console.log(usersFound);
});

＆＃13;

Answer 2

您的代码段问题在于您使用的是_.pluck而不是_.select。这是underscore.js解决方案：

const groups = {
    groupid1: "metadata",
    groupid2: "metadata"
};

const users = [{
        name: "something",
        groups: ["groupid1", "groupid2"]
    },
    {
        name: "something else ",
        groups: ["groupid1"]
    },
    {
        name: "something else again",
        groups: ["groupid2"]
    },
];

_.each(_.keys(groups), group => {
    const usersArray = _.select(users, user => {
        return user.groups.indexOf(group) > -1;
    });
    console.log(usersArray);
});

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js"></script>

从这个答案的评论中回答作者的另一个问题：

我想扩展问题，将两者的结果推送到一个数组中，而不是包含重复数据

const groups = {
    groupid1: "metadata",
    groupid2: "metadata"
};

const users = [{
        name: "something",
        groups: ["groupid1", "groupid2"]
    },
    {
        name: "something else ",
        groups: ["groupid1"]
    },
    {
        name: "something else again",
        groups: ["groupid2"]
    },
];

let usersArray = [];
_.each(_.keys(groups), group => {
    usersArray = _.union(usersArray, _.select(users, user => {
        return user.groups.indexOf(group) > -1;
    }));
});
console.log(usersArray);

<script src="https://cdnjs.cloudflare.com/ajax/libs/underscore.js/1.9.1/underscore-min.js"></script>

UnderscoreJS - 从属于组的阵列中提取用户

2 个答案: