Error if attempting to add a non-unique ISBN value

Signed-off-by: Pekka Helenius <fincer89@hotmail.com>

bookstore/src/main/java/com/fjordtek/bookstore/model/Book.java

@@ -120,9 +120,7 @@ public class Book {
 	private int year;
 
 	//////////
-	@Column(
-			unique  = true
-			)
+	@Column(unique  = true)
 	@NotBlank(
 			message = "Fill the ISBN code form"
 			)

bookstore/src/main/java/com/fjordtek/bookstore/web/BookController.java

@@ -118,13 +118,16 @@ public class BookController {
 			HttpServletRequest requestData
 			) {
 
+		// TODO consider better solution. Add custom Hibernate annotation for Book class?
+		if (bookRepository.existsByIsbn(book.getIsbn())) {
+			bindingResult.rejectValue("isbn", "error.user", "ISBN code already exists");
+		}
+
 		if (bindingResult.hasErrors()) {
 			httpServerLogger.commonError("Book add: error " + book.toString(), requestData);
 			return bookAddPageView;
 		}
 
-		bookRepository.save(book);
-
 		httpServerLogger.logMessageNormal(
 				requestData,
 				bookAddPageView + ": " + "HTTPOK"