db={"items":[{"_id":"1e44kgsl1s","info":{"slug":"otaceni-na-dalnici"},"votes_count":9}],"poll_votes":[{"_id":"1e44kgsl1s_1e41795qjw","poll":"1e44kgsl1s","user":"1e41795qjw","vote":"dislike"},{"_id":"xyz","poll":"1e44kgsl1s","user":"abc","vote":"abc"},{"_id":"ijk","poll":"1e44kgsl1s","user":"qwerty","vote":"qwerty"},]}

db.items.aggregate([{$match:{"info.slug":"otaceni-na-dalnici"}},{$lookup:{from:"poll_votes",let:{poll_id:"$_id"},pipeline:[{$match:{$and:[{$expr:{$eq:["$poll","$$poll_id"]}},{user:"1e41795qjw"}]}},{$project:{_id:0,vote:"$vote"}}],as:"me"}}])