Ghost collections auto-created for each subdocument

[sandorvasas]

Do you want to request a feature or report a bug?
BUG

What is the current behavior?
I don't know since when this is happening, I just noticed recently that empty collections were created in our DB. one collection for each subdocument in the schema. For example, if we have a schema like

export const PawSchema = new mongoose.Schema({
  size: Number,
  temperature: Number
});
export const PawModel = mongoose.model('Paw', PawSchema)

export const DoggoSchema = new mongoose.Schema({
  chonkiness: Number,
  paws: [PawSchema]
}, {
  timestamps: {
    createdAt: 'createdAt',
    updatedAt: 'updatedAt',
  },
  collection: 'doggos',
});
export const DoggoModel = mongoose.model('Doggo', DoggoSchema)

Results in two automatically created collections: paws and doggos. This had not been happening before. collection above is only defined for doggos, so it should only create doggos, as before.

What are the versions of Node.js, Mongoose and MongoDB you are using? Note that "latest" is not a version.
Mongoose 6.2.1
Node 16.14
MongoDB 4.4.12

[sandorvasas]

Can be disabled with mongoose.set('autoCreate', false)

[sandorvasas]

Thanks.

[sandorvasas]

np

[Uzlopak]

Actually when do you use PawModel?

[Uzlopak]

I assume you never actually need PawModel, so you can delete PawModel.

[sandorvasas]

It actually didn't work. Ghost collections are still created all around. I even tried setting { autoCreate: false } on all the schemas.
I do need PawModel for example when pushing new PawModel({...}) into another model's nested array, but that's not the point here. I just want to be able to make it work again as it had been working before.

[vkarpov15]

@sandorvasas you don't need PawModel if all you're doing is pushing onto another model's nested array. In general, if you don't need a collection, you don't need a model.