Converting string to date in MongoDB?

To convert the string to date in MongoDB, use the $dateFromString operator within an aggregation pipeline. This operator parses a string and converts it to a proper date object.

Syntax

db.yourCollectionName.aggregate([
    {
        $project: {
            anyVariableName: {
                $dateFromString: {
                    dateString: '$yourFieldName'
                }
            }
        }
    }
]);

Sample Data

Let us create a collection with some documents to understand the string to date conversion ?

db.ConvertStringToDateDemo.insertMany([
    {"ArrivalDate": "20-10-2019"},
    {"ArrivalDate": "21-02-2019"},
    {"ArrivalDate": "10-12-2018"},
    {"ArrivalDate": "31-01-2017"}
]);

{
    "acknowledged" : true,
    "insertedIds" : [
        ObjectId("5c6ef3596fd07954a489069f"),
        ObjectId("5c6ef3616fd07954a48906a0"),
        ObjectId("5c6ef36d6fd07954a48906a1"),
        ObjectId("5c6ef37b6fd07954a48906a2")
    ]
}

Display all documents from the collection ?

db.ConvertStringToDateDemo.find().pretty();

{
    "_id" : ObjectId("5c6ef3596fd07954a489069f"),
    "ArrivalDate" : "20-10-2019"
}
{
    "_id" : ObjectId("5c6ef3616fd07954a48906a0"),
    "ArrivalDate" : "21-02-2019"
}
{
    "_id" : ObjectId("5c6ef36d6fd07954a48906a1"),
    "ArrivalDate" : "10-12-2018"
}
{
    "_id" : ObjectId("5c6ef37b6fd07954a48906a2"),
    "ArrivalDate" : "31-01-2017"
}

Example: Converting String to Date

Here is the query to convert string to date using $dateFromString ?

db.ConvertStringToDateDemo.aggregate([
    {
        $project: {
            StringToDate: {
                $dateFromString: {
                    dateString: '$ArrivalDate'
                }
            }
        }
    }
]);

{
    "_id" : ObjectId("5c6ef3596fd07954a489069f"),
    "StringToDate" : ISODate("2019-10-20T00:00:00Z")
}
{
    "_id" : ObjectId("5c6ef3616fd07954a48906a0"),
    "StringToDate" : ISODate("2019-02-21T00:00:00Z")
}
{
    "_id" : ObjectId("5c6ef36d6fd07954a48906a1"),
    "StringToDate" : ISODate("2018-12-10T00:00:00Z")
}
{
    "_id" : ObjectId("5c6ef37b6fd07954a48906a2"),
    "StringToDate" : ISODate("2017-01-31T00:00:00Z")
}

Key Points

• The $dateFromString operator automatically parses common date formats
• Use this operator within the $project stage of aggregation pipeline
• The result is an ISODate object that can be used for date operations

Conclusion

Use $dateFromString within an aggregation pipeline to convert string representations of dates into proper date objects. This enables date−based queries and operations on your MongoDB documents.