Merge entity collections

Author: AnghelLeonard

HibernateSpringBootMergeCollections/src/main/java/com/bookstore/MainApplication.java

@@ -28,8 +28,7 @@ public ApplicationRunner init() {
             System.out.println("------------------- Joana Nimar's Books --------------------");
             List<Book> books = bookstoreService.fetchBooksOfAuthor("Joana Nimar");
 
-            books.forEach(b -> System.out.println("Title: "
-                    + b.getTitle() + " | id:(" + b.getId() + ")"));
+            books.forEach(b -> System.out.println(b));
 
             System.out.println("---------- Books of Joana Nimar Updated Detached ------------");
 
@@ -45,14 +44,12 @@ public ApplicationRunner init() {
             book.setIsbn("005-JN");
             books.add(book);
 
-            books.forEach(b -> System.out.println("Title: "
-                    + b.getTitle() + " | id:(" + b.getId() + ")"));
-
+            books.forEach(b -> System.out.println(b));
+            
             System.out.println("----------------- Books of Joana Nimar Merged ----------------");
             bookstoreService.updateBooksOfAuthor("Joana Nimar", books);
 
-            books.forEach(b -> System.out.println("Title: "
-                    + b.getTitle() + " | id:(" + b.getId() + ")"));
+            books.forEach(b -> System.out.println(b));
         };
     }
-}
+}

HibernateSpringBootMergeCollections/src/main/java/com/bookstore/entity/Book.java

@@ -60,6 +60,10 @@ public void setAuthor(Author author) {
     @Override
     public boolean equals(Object obj) {
 
+        if(obj == null) {
+            return false;
+        }
+        
         if (this == obj) {
             return true;
         }

HibernateSpringBootMergeCollections/src/main/java/com/bookstore/service/BookstoreService.java

@@ -35,18 +35,21 @@ public void updateBooksOfAuthor(String name, List<Book> books) {
 
         // Remove the existing database rows that are no 
         // longer found in the incoming collection (books)
-        author.getBooks().removeIf(b -> !books.contains(b));
+        List<Book> toRemove = author.getBooks().stream()
+                .filter(b -> !books.contains(b))
+                .collect(Collectors.toList());
+        toRemove.forEach(b -> author.removeBook(b));
 
         // Update the existing database rows which can be found 
         // in the incoming collection (books)
         List<Book> newBooks = books.stream()
                 .filter(b -> !author.getBooks().contains(b))
-                .collect(Collectors.toList());             
+                .collect(Collectors.toList());
 
         books.stream()
                 .filter(b -> !newBooks.contains(b))
                 .forEach((b) -> {
-                    b.setAuthor(author);                       
+                    b.setAuthor(author);
                     Book mergedBook = bookRepository.save(b);
                     author.getBooks().set(
                             author.getBooks().indexOf(mergedBook),

HibernateSpringBootMergeCollections/src/main/resources/data-mysql.sql

@@ -3,4 +3,4 @@ insert into author (age, name, genre, id) values (34, "Joana Nimar", "History",
 insert into book (isbn, title, author_id, id) values ("001-JN", "A History of Ancient Prague", 2, 1);
 insert into book (isbn, title, author_id, id) values ("002-JN", "A People's History", 2, 2);
 insert into book (isbn, title, author_id, id) values ("001-MJ", "The Beatles Anthology", 1, 3);
-insert into book (isbn, title, author_id, id) values ("001-OG", "Carrie", 2, 4);
+insert into book (isbn, title, author_id, id) values ("007-JN", "Carrie", 2, 4);