Can't build query with nested primaryKey

[marksitko]

Hey,
first thanks for the great package and your effort!

The primary key of my Model is under data.id, the problem is, that Javascript can't resolve an Object by string dot notation.

It try's to check if my Model instance has a valid ID with the hasId Method. Insides the hasId Method it try's to access the primaryKey through getPrimaryKey() with this[this.primaryKey()];.

This would be equivalent to access an object like this and resolves to undefined:

const o = {
    data: {
        id: 1,
    },
};

o['data.id'];

// my model
export default class User extends Model {
  primaryKey() {
    return 'data.id';
  }

  resource() {
    return 'users';
  }
}

Is there any other solution? If not i think it should be possible to access objects through a provided path as a string.