Calculate entity property at INSERT or UPDATE time

Author: AnghelLeonard

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

@@ -1,5 +1,6 @@
 package com.bookstore;
 
+import com.bookstore.entity.Book;
 import com.bookstore.service.BookstoreService;
 import org.springframework.boot.ApplicationRunner;
 import org.springframework.boot.SpringApplication;
@@ -23,6 +24,9 @@ public static void main(String[] args) {
     public ApplicationRunner init() {
         return args -> {
             bookstoreService.insertBook();
+            
+            Book book = bookstoreService.fetchBook();
+            System.out.println(book);
         };
     }
 }

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

@@ -26,8 +26,7 @@ public class Book implements Serializable {
     // @Column(name="...", insertable=false)
 
     @Generated(value = GenerationTime.ALWAYS)
-    @Column(insertable = false, updatable = false,
-            columnDefinition = "double AS (price - price * 0.25)")
+    @Column(insertable = false, updatable = false /*, columnDefinition = "double AS (price - price * 0.25)") */)            
     private double discount;
 
     public Long getId() {

HibernateSpringBootCalculatePropertyGenerated/src/main/java/com/bookstore/repository/BookRepository.java

@@ -5,5 +5,7 @@
 import org.springframework.stereotype.Repository;
 
 @Repository
-public interface BookRepository extends JpaRepository<Book, Long> {      
+public interface BookRepository extends JpaRepository<Book, Long> { 
+    
+    public Book findByTitle(String title);
 }

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

@@ -8,23 +8,27 @@
 
 @Service
 public class BookstoreService {
-    
+
     private static final Logger logger
             = Logger.getLogger(BookstoreService.class.getName());
-    
+
     private final BookRepository bookRepository;
-    
-    public BookstoreService(BookRepository bookRepository) {        
+
+    public BookstoreService(BookRepository bookRepository) {
         this.bookRepository = bookRepository;
     }
-        
+
     public void insertBook() {
         Book book = new Book();
-        
-        book.setTitle("Title_1");
-        book.setIsbn("Isbn_1");
+
+        book.setTitle("Ancient History");
+        book.setIsbn("001-AH");
         book.setPrice(13.99);
-        
+
         bookRepository.save(book);
     }
+
+    public Book fetchBook() {
+        return bookRepository.findByTitle("Ancient History");
+    }
 }

HibernateSpringBootCalculatePropertyGenerated/src/main/resources/application.properties

@@ -2,10 +2,12 @@ spring.datasource.url=jdbc:mysql://localhost:3306/bookstoredb?createDatabaseIfNo
 spring.datasource.username=root
 spring.datasource.password=root
 
-spring.jpa.hibernate.ddl-auto=create
+spring.jpa.hibernate.ddl-auto=none
 spring.jpa.show-sql=true
 
 spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect
 
 spring.jpa.open-in-view=false
 
+spring.datasource.initialization-mode=always
+spring.datasource.platform=mysql

HibernateSpringBootCalculatePropertyGenerated/src/main/resources/schema-mysql.sql

@@ -0,0 +1,9 @@
+CREATE TABLE `book` (
+  `id` bigint(20) NOT NULL AUTO_INCREMENT,
+  `discount` double GENERATED ALWAYS AS ((`price` - (`price` * 0.25))) VIRTUAL,
+  `isbn` varchar(255) DEFAULT NULL,
+  `price` double NOT NULL,
+  `title` varchar(255) DEFAULT NULL,
+  PRIMARY KEY (`id`)
+) ENGINE=MyISAM AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_0900_ai_ci;
+SELECT * FROM bookstoredb.book;