Format date value in MongoDB shell?

To format date values in MongoDB shell, use the $dateToString operator within an aggregation pipeline. This operator converts ISODate values into custom formatted strings according to your specified format pattern.

Syntax

{
    "$dateToString": {
        "format": "formatString",
        "date": "$dateField"
    }
}

Sample Data

db.demo480.insertMany([
    { "id": 1, "DueDate": new ISODate("2020-01-10") },
    { "id": 1, "DueDate": new ISODate("2017-12-21") },
    { "id": 1, "DueDate": new ISODate("2019-10-12") },
    { "id": 1, "DueDate": new ISODate("2019-12-01") }
]);

{
    "acknowledged": true,
    "insertedIds": [
        ObjectId("5e821056b0f3fa88e2279098"),
        ObjectId("5e821062b0f3fa88e2279099"),
        ObjectId("5e82106ab0f3fa88e227909a"),
        ObjectId("5e821078b0f3fa88e227909b")
    ]
}

Display all documents from the collection ?

db.demo480.find();

{ "_id": ObjectId("5e821056b0f3fa88e2279098"), "id": 1, "DueDate": ISODate("2020-01-10T00:00:00Z") }
{ "_id": ObjectId("5e821062b0f3fa88e2279099"), "id": 1, "DueDate": ISODate("2017-12-21T00:00:00Z") }
{ "_id": ObjectId("5e82106ab0f3fa88e227909a"), "id": 1, "DueDate": ISODate("2019-10-12T00:00:00Z") }
{ "_id": ObjectId("5e821078b0f3fa88e227909b"), "id": 1, "DueDate": ISODate("2019-12-01T00:00:00Z") }

Example: Format Date with Custom Pattern

Format dates as "YYYY-MM-DD HH-MM" and sort by descending date order ?

db.demo480.aggregate([
    { "$match": { "id": 1 } },
    { "$sort": { "DueDate": -1 } },
    {
        "$project": {
            "_id": 0,
            "DueDate": {
                "$dateToString": {
                    "format": "%Y-%m-%d %H-%M",
                    "date": "$DueDate"
                }
            }
        }
    }
]);

{ "DueDate": "2020-01-10 00-00" }
{ "DueDate": "2019-12-01 00-00" }
{ "DueDate": "2019-10-12 00-00" }
{ "DueDate": "2017-12-21 00-00" }

Key Points

• %Y = 4-digit year, %m = month (01-12), %d = day (01-31)
• %H = hour (00-23), %M = minute (00-59), %S = second (00-59)
• Use within $project stage of aggregation pipeline for formatting output

Conclusion

The $dateToString operator provides flexible date formatting in MongoDB aggregation pipelines. Use format specifiers like %Y-%m-%d to convert ISODate objects into readable string representations.