限制Firebase中的有序列表

Question

I have this: 我有这个：

name  |  age
______|_____
Anne  |  28
Carl  |  20 
Sarah |  13
Lucy  |  56
John  |  22 
Mark  |  44

How do I retrieve the name of the 3 youngest people with Firebase? 如何使用Firebase检索3个最年轻的人的姓名？

I tried with: 我尝试过：

return firebase.database().ref('myUsers').orderByChild("age").startAt().limit(3);

but I get an error: 但是我收到一个错误：

Supplied parameters do not match any signature of call target.

Answer 1

Data in firebase is ordered lexicographically, so you'll have to get the last of them. firebase中的数据按字典顺序排序，因此您必须获取最后一个。

return firebase.database().ref('myUsers').orderByChild("age").limitToLast(3);