$toJson()

class User extends Model {
  static entity = 'users'
  @Attr('') declare id: number
  @Str('') declare name: string
  @HasMany(() => Post, 'userId') declare posts: Post[]
}
const user = new User({ id: 1, name: 'John Doe', posts: [{ id: 1, title: 'Merry Christmas' }] })
user.$toJson()
// {
//    id: 1,
//    name: 'John Doe',
//    posts: [{ id: 1, title: 'Merry Christmas' }],
// }

function $toJson(model?: Model, options: ModelOptions = {}): Element