Database
db={books:[{"_id":"SHN-E3AE0DB3BC7D-4214-BDAE-59140DA1F850","nameOfBook":"test","nameOfAuthor":"test authou","yearOfPublication":"1998","publication":"test","edition":"test","status":"available","price":"test","addedOn":"2021-10-27T08:39:00.147+0000"}],bookStocks:[{"_id":"SHNC-E1C6CF22A055-4A7E-AB79-CAEDC65AB29C","bookId":"SHN-E3AE0DB3BC7D-4214-BDAE-59140DA1F850","collegeId":"COL-D0E03FA4803F-4224-A321-1801626A9942","course":"bcom","bookDetails":"eeff","status":"available","addedOn":"2021-11-01T08:26:54.916+0000"}]}
Query
db.books.aggregate([{"$lookup":{"from":"bookStocks","localField":"_id","foreignField":"bookId","as":"bookStocks"}},{$match:{"bookStocks.collegeId":"COL-D0E03FA4803F-4224-A321-1801626A9942"}},])