fix(book-new): add correct id mapping for json-server

Author: robinboehm

src/app/book/book-new/book-new.component.ts

@@ -26,7 +26,8 @@ export class BookNewComponent implements OnInit {
   onSubmit() {
 
     const book: Book = {
-      isbn: '',
+      id: this.form.value.isbn,
+      isbn: this.form.value.isbn,
       title: this.form.value.title,
       author: this.form.value.author,
       subtitle: '',

src/app/book/shared/book.ts

@@ -1,4 +1,5 @@
 export interface Book {
+  id?: string,
   title: string;
   subtitle: string;
   isbn: string;