facing query problem in Mongodb Aggregation by based on ObjectID [closed]
Try this:
db.collection.aggregate([ { $match: { // match only relevant documents. } }, { $group: { _id: "$user_name", coordinates: {$push: {longitude: "$longitude", latitude: "$latitude"}} } }, { $replaceRoot: { newRoot: {$arrayToObject: [[{k: "$_id", v: "$coordinates"}]]} } }])