db={conversations2:[{"_id":{"$oid":"65c0f64030054c4b8f0481a0"},"otherUserId":{"$numberLong":"45"},otherUserBlocked:true,"userId":{"$numberLong":"32"},"unreadMessageCount":29},{"_id":{"$oid":"65c0f64030054c4b8f0481a1"},"otherUserId":{"$numberLong":"46"},otherUserBlocked:false,"userId":{"$numberLong":"32"},"unreadMessageCount":10},{"_id":{"$oid":"65c0f64030054c4b8f0481a2"},"otherUserId":{"$numberLong":"47"},otherUserBlocked:false,"userId":{"$numberLong":"32"},"unreadMessageCount":0}],user_blocked:[{"_id":{"$oid":"660285eb2be53086024608e6"},"id":45},{"_id":{"$oid":"660285eb2be53086024608e7"},"id":555}]}

db.conversations2.aggregate([{$match:{userId:32,otherUserBlocked:false,unreadMessageCount:{$gt:0}}},{$group:{_id:"$userId",unreadMessageCount:{$sum:"$unreadMessageCount"}}}])