Moongose schema type not working in aggregate

Question

I have the schema

const UserSchema = new Schema({
    _id: {
      type: String,
      require: true
    },
    paused: {
      type: Boolean,
      default: false
    },
    name: {
      type: String,
      default: ''
    },
    type: {
      type: String,
      enum: ['private', 'group']
    },
})

const PasswordSchema = new Schema({
    password: {
      type: String,
      require: true
    },
    used: {
      type: Boolean,
      default: false,
    },
    usedBy: UserSchema
})

Like this, works fine

await Password.findOne({"usedBy._id": 123}) // 123 is converted to string

But aggregate is not converting the _id

await Password.aggregate().match({ "usedBy._id": 123 }) // 123 keeps number, so the query returns null

This is normal? I didn't want to have to convert the _id manually in all queries

Answer 1

According to the issue: https://github.com/Automattic/mongoose/issues/10032

This is expected:

Mongoose doesn't cast aggregation pipelines. That's because aggregation pipelines can, and usually do, change the shape of the data in MongoDB. If you need casting, you can use find(), or you can use the Query#cast() method to cast the filter:

await Password.aggregate().match(new Query({ "usedBy._id": 123 }).cast(Password).getFilter())