[{_id:ObjectId("5ea3069ff3908ac63adfbc8a"),name:"product 1",value:1},{_id:ObjectId("1113069ff3908ac63adfbc11"),name:"product 2",value:1}]

db.collection.aggregate([{$replaceRoot:{newRoot:{$mergeObjects:[{$arrayToObject:[[{k:{$toString:"$_id"},v:"$name"}]]},"$$ROOT"]}}}])