Reactive Forms correctly convert Form Value to Model Object

This constructor will work with any type and will assign any matching filed.

export class Book {
  public constructor(init?: Partial<Book>) {
        Object.assign(this, init);
    }
}

So you will be able to do this:

this.newBook = new Book(this.bookFormGroup.value);

This will save you a lot of work if the Book class will have any change in future and became bigger.