从Firebase获取随机物品 [英] Get random item from Firebase

问题描述

我搜索了它，但是所有答案都还很老，所以也许有更好的方法.我正在尝试从Firebase数据库中获取一个随机项目，如下所示:

I searched for it, but all the answers are pretty old so maybe there is a better way. I'm trying to get a random item from a Firebase DB which looks like this:

我想得到一个随机用户，仅此而已.

I want to get a random user, that is all.

有什么想法吗?

推荐答案

如果知道有多少用户，则可以执行以下操作:

If you know how many users there are, you can do this:

const numberOfUsers = 15;
const randomIndex = Math.floor(Math.random() * numberOfUsers);

var ref = firebase.database().ref('companies/01/users');

ref.limitToFirst(randomIndex).limitToLast(1).once('value').then(snapshot =>
{
    var user = snapshot.val();
    // do something with the user data
});

但是，如果您不知道有多少个孩子(或在其他位置存储了孩子列表)，则没有直接的方法来解决此问题，而无需先在树中接收所有孩子.参见

However, if you don't know how many children there are (or have a children list stored somewhere else), there is no direct way to solve this problem without first receiving all children in the tree. See In Firebase, is there a way to get the number of children of a node without loading all the node data? for more info.

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