MongoDb: Convert date string to specific format in mongodb 3.6

Question

I need to parse date value to specific format without using format field in dateFromString operator.

Mongo Playground

Current situation : in Mongodb 4.0 if I f

Answer 1

If I get the requirement right, Try the following query which uses: $dateFromParts

Input:

[
  {
    "date": ISODate("2020-01-16T08:54:17.604Z")
  }
]

Query:

db.collection.aggregate([
  {
    $project: {
      outputDate: {
        $dateFromParts: {
          "year": {
            $year: "$date"
          },
          "month": {
            $month: "$date"
          },
          "day": {
            $dayOfMonth: "$date"
          },
          "hour": {
            $hour: "$date"
          }
        }
      }
    }
  }
]);

O/P:

[
  {
    "_id": ObjectId("5a934e000102030405000000"),
    "outputDate": ISODate("2020-01-16T08:00:00Z")
  }
]

Playground Test Link