Add type-safe method to access model class by instance

Problem

Given an arbitrary model instance, I would like to know which specific model this instance belongs to.

Example use case: in a Model.beforeInsert global hook, I would like to recognize each of inputItems’s model class (e.g. look up its tableName).

I can already access it with item.constructor but it’s typed as Function so I have to use ugly casts like:

if (item instanceof Model) {
  console.log((item.constructor as ModelClass<Model>).tableName)
}

Proposed API addition

There could be an instance level getter item.$modelClass which would simply return this.constructor properly typed.

[koskimas]

Actually that’s what the query builder’s modelClass() method also returns. I’ll add the getter.

[koskimas]

There’s no way to add a method, getter or a property that has the type typeof this, which would be the correct type of this.constructor. Typescript simply doesn’t allow that. We could add $modelClass: ModelClass<this> but that will only contain the static interface of the Model base class and none of the static methods defined for the subclass. Adding such property feels like a hack.