Using %stringToOid with an array

My JWT payload, and therefore user.data, contains an array with some objectId string representations.

In a rule to validate write permissions, I want to compare the document _id with this array via the $in operator.

{
    "_id": {
        "$in" {
            "%stringToOid": "%%user.data.myKey"
        }
    }
}

Problem %stringToOid only seems to allow string and not an array of strings.

How to work around this issue ?

Thanks

Hi and sorry for my late response.

I’m not allowed to add attachement as I’m a new user. You’ll find a small sample of user.data and project collection add the end of this post.

I think my previous post may be a bit misleading. I’m using Atlas App services (mongo realm) and realm SDK on react-native side.
The App use CustomJWTProvider (https://www.mongodb.com/docs/atlas/app-services/authentication/custom-jwt/) to log into my App Services application and the JWT payload contains some information on projects (small array of ObjectId) that should be provided to the application.

I’m not sure I understand how to apply a $unwind in the “read” section a RuleExpression (https://www.mongodb.com/docs/atlas/app-services/rules/expressions/).
Can these behave like an AggregateQuery?

I still tried the following two possibilities, that are probably wrong, without success (no results are returned, no errors are returned in the app and in the AppService logs)

{
  "_id": {
    "$in": {
      "%stringToOid": {
        "$unwind": "%%user.data.allowedProjects"
      }
    }
  }
}

{
  "_id": {
    "%stringToOid": {
      "$unwind": "%%user.data.allowedProjects"
    }
  }
}

The following rules works as expected:

{
  "idStr": {
    "$in": "%%user.data.allowedProjects"
  }
}

{
  "_id": {
    "%stringToOid": "%%user.data.test"
  }
}

But the one I’d like to use doesn’t:

{
  "_id": {
    "$in": {
      "%stringToOid": "%%user.data.allowedProjects"
    }
  }
}

Here is a test JWT payload:

{
    "test": "6622acd1cda914c2c9b307c1",
    "allowedProjects": ["6622acd1cda914c2c9b307c1", "665dcf4df09775c14a40a584"]
}

Here is a test Projects collection

[{
  "_id": {
    "$oid": "6622acd1cda914c2c9b307c1"
  },
  "idStr": "6622acd1cda914c2c9b307c1",
  "name": "Test project 1"
},
{
  "_id": {
    "$oid": "665dcf4df09775c14a40a584"
  },
  "idStr": "665dcf4df09775c14a40a584",
  "name": "Test project 2"
}]

Currently, as a workaround, I’m keeping a stringified version of my _id aside other properties to match it against my JWT.

Thanks again,
Quentin