Database
[{"date":ISODate("2020-01-16T08:54:17.604Z"),"dateS":"2020-01-16T08"}]
Query
db.collection.aggregate([{$project:{dateHour:{$dateToString:{format:"%Y-%m-%dT%H",date:"$date"},},parsedDate:{$dateFromString:{dateString:"$dateS",format:"%Y-%m-%dT%H"}}}}])