Converting a field to another type and updating the entire collection in Bulk?

Question

Here, in my collection, I have "numerical" and "date" field save as string, but I want both of them to be Integer how I can do that. Here is my collection

{
   "name": "Thyame",
   "salary": "25000",
   "dob": "1988-01-25"
}

and the expected output is

{
   "name": "Thyame",
   "salary": 25000,
   "dob": ISODate("1988-01-25T00:00:00.000Z")
}

Answer 1

You may perform MongoDB aggregation to change data type and override your entire collection with $out operator.

Try this one:

db.collection.aggregate([
  {
    $project: {
      name: "$name",
      salary: {
        $toInt: "$salary"
      },
      dob: {
        $dateFromString: {
          dateString: "$dob",
          format: "%Y-%m-%d"
        }
      }
    }
  }
//,{$out:"collection"}
])

MongoPlayground

Note: If you uncomment $out, it will override all records with aggregation result.