Can FindOne() return "typed JSON" (createdAt: {$date: "..."}, instead of createdAt: "..." etc.)

[_alex]

Normally, when using findOne() command, one will get an object that will look like this:

{
  id: "...",
  createdAt: "..."
}

I would like this object to be in the same form I can see when inserting documents in Atlas, or using mongoexport:

{
  id: {
    $oid: "..." 
  },
  createdAt: {
    $date: "..."
  }
}

Is that possible with the findOne() method, or some other approach?
I am trying to do it in a Realm function, so using database tools, like mongoexport, are not an option.

[MaBeuLux88 (Maxime Beugnet)]

Hi @_alex,

Would that work for you?

exports = function(arg){
    const coll = context.services.get("mongodb-atlas").db("test").collection("test");
    return coll.findOne().then((doc) => {
      const s = EJSON.stringify(doc);
      console.log(s);
      return s;
    });
};

Result:

> ran on Tue Sep 28 2021 21:07:39 GMT+0200 (Central European Summer Time)
> took undefined
> logs: 
{"_id":{"$oid":"61536690650d531e1c196bdd"},"date":{"$date":{"$numberLong":"1293922800000"}}}
> result: 
"{\"_id\":{\"$oid\":\"61536690650d531e1c196bdd\"},\"date\":{\"$date\":{\"$numberLong\":\"1293922800000\"}}}"
> result (JavaScript): 
EJSON.parse('"{\"_id\":{\"$oid\":\"61536690650d531e1c196bdd\"},\"date\":{\"$date\":{\"$numberLong\":\"1293922800000\"}}}"')

If I use the JSON helper instead of the EJSON one, I get this result instead:

> ran on Tue Sep 28 2021 21:08:42 GMT+0200 (Central European Summer Time)
> took undefined
> logs: 
{"_id":"61536690650d531e1c196bdd","date":"2011-01-01T23:00:00.000Z"}
> result: 
"{\"_id\":\"61536690650d531e1c196bdd\",\"date\":\"2011-01-01T23:00:00.000Z\"}"
> result (JavaScript): 
EJSON.parse('"{\"_id\":\"61536690650d531e1c196bdd\",\"date\":\"2011-01-01T23:00:00.000Z\"}"')

Doc for the different helpers available: https://docs.mongodb.com/realm/functions/json-and-bson/

Cheers,
Maxime.

[_alex]

Thank you so much, @MaBeuLux88. This is exactly what I was looking for!