Query MongoDB with a regex expression against an ObjectId

Question

Is it possible to do a query like:

db.artigo.find( { _id : ObjectId('520a504a3004bc615fcfcf16') } )

but using a regex on ObjectId?

For example, do get _ids that contains "004" on that position above.

PS. The reason is to implement a shorty service based on some fields, namely the _id. I'm trying to create an implicit "shorty" service instead of an explicit one (with a field generated for the purpose).

Answer 1

• ObjectId is not a string but a special type in MongoDB. You can not
  query with a regex expression operator against a field that contains ObjectId's.
• But... _id doesn't have to be an ObjectId, so what i would suggest is providing your own unique string as _id then you can use a regex
  expression for querying.

Answer 2

ObjectId is not a string but a special type in MongoDB. You can not query with a regex expression operator against a field that contains ObjectId's.

_id doesn't have to be an ObjectId, so what I would suggest is providing your own unique string as _id then you can use a regex the expression for querying.

Example:

let userId = 'bf44fa';

const result = await Users.aggregate([
  {
    $addFields: {
      tempUserId: { $toString: '$_id' },
    }
  },
  {
    $match: {
      tempUserId: { $regex: userId, $options: "i" }
    }
  }
]).exec();

Now we can find by _id with the last 6 digits or start 6 digits by using aggregation as your wish.