Database
[{"_id":"624c0ac20f0df948f8bf8cf1","collection_name":"pog7","by":"soeww","private":"$2a$10$U3dRJxUQLm9GvuS5g3qkF.fMVJCdxrLAarFiGQ900EarayWBvrZya","fens":[{"fen":"pog","san":"d4","_id":"624c0ac20f0df948f8bf8cf2"}],"__v":0},{"_id":"624c0ac20f0df948f8bf8cf15","collection_name":"pog7","by":"soeww","private":"$2a$10$U3dRJxUQLm9GvuS5g3qkF.fMVJCdxrLAarFiGQ900EarayWBvrZya","fens":[{"fen":"pog","san":"d4","_id":"624c0ac20f0df948f8bf8cf3"}],"__v":0},]
Query
db.collection.find({fens:{$elemMatch:{_id:"624c0ac20f0df948f8bf8cf2"}}})