UnderscoreJS - 从属于某个组的数组中拉取用户

Question

我有一个组对象：

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

以及一组用户：

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

我想遍历组 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，每个组一个：

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

问题是这返回给我一个未定义的数组，而不是一个用户对象数组。即使只返回用户名也很好。

感谢您提供的任何帮助！对于可扩展性，下划线是解决这个问题的首选方法。

Answer 1

如 docs 中所述，_.pluck() 有两个参数：列表和属性名称 - 您提供的不是属性名称，而是一个函数。但更重要的是，这不是您使用 _.pluck() 函数的目的（再次检查文档）。

在你的情况下，你甚至根本不需要使用 UnderscoreJS：

// 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);
});

Answer 2

您的代码段存在问题，因为您使用的是 _.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>

根据此回答的评论回答作者的另一个问题：

I wanted to extend the question to push the results from both into a single array, and not include duplicates

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 - 从属于某个组的数组中拉取用户

UnderscoreJS - Pull users from an Array who are part of a group

javascript

underscore.js