How to find a particular subdocument in a document by condition?

subdocument_find.js

// example when using _id as a query condition
// need to utilize the $element and $ (Positional projection)

> db.users.find({"_id": ObjectId("5974c986dea685349a68242a"), 'userLocation': {"$elemMatch": {'locationName': "Uni Kebab"}}}, {"userLocation.$": 1}).pretty();
{
	"_id" : ObjectId("5974c986dea685349a68242a"),
	"userLocation" : [
		{
			"locationName" : "Uni Kebab",
			"locationAddress" : "190 Burgess Road, Southampton",
			"place_id" : "ChIJ2WK8mvNzdEgRyilaQFDCp1M",
			"coords" : [
				-1.3924609,
				50.9382747
			],
			"_id" : ObjectId("597b8a68766520512f8ad76c"),
			"createdOn" : ISODate("2017-07-28T19:03:04.501Z")
		}
	]
}

// example when using other filed as a query string
> db.users.find({"email": "Alice@gmail.com", 'userLocation': {"$elemMatch": {'locationName': "Uni Kebab"}}}, {"userLocation.$": 1}).pretty();
{
	"_id" : ObjectId("5974c986dea685349a68242a"),
	"userLocation" : [
		{
			"locationName" : "Uni Kebab",
			"locationAddress" : "190 Burgess Road, Southampton",
			"place_id" : "ChIJ2WK8mvNzdEgRyilaQFDCp1M",
			"coords" : [
				-1.3924609,
				50.9382747
			],
			"_id" : ObjectId("597b8a68766520512f8ad76c"),
			"createdOn" : ISODate("2017-07-28T19:03:04.501Z")
		}
	]
}