Aggregating arrays of data in mongodb

Question

I want to check consecutive value of certain items inside a number of arrays in nodejs is there any aggregation technique that can help. suppose i have 5 objects in an array and each object has cetain parameter such as

var arr = [{name: abc,age:10},
{name: gtt,age:12},
{name: sss,age:13},
{name: dddttt,age:14},
{name: abc,age:4} ]

now i want to check that in each object the age is less than 10.what i can do is loop through the array and check every condition and make count or push value. but i want to know is there any technique

Answer 1

首先，您应该$ unwind，它会发生，数组的每个项目都是单独的对象，稍后；

{$match: {"$age": {$lt: 10}}}