find maximum value in object mongodb code example

Example 1: mongodb get maximum value from collection

db.collection.aggregate([{
	$group : { _id: null, max: { $max : "$age" }}
}]);

Example 2: mongodb get max value

db.collection.find().sort({age:-1}).limit(1) // for MAX
db.collection.find().sort({age:+1}).limit(1) // for MIN