Join Fetch

Author: AnghelLeonard

HibernateSpringBootJoinFetch/hibernate spring boot join fetch.png

@@ -4,17 +4,17 @@
     <modelVersion>4.0.0</modelVersion>
 
     <groupId>com.jpa</groupId>
-    <artifactId>jpa</artifactId>
+    <artifactId>HibernateSpringBootJoinFetch</artifactId>
     <version>1.0</version>
     <packaging>jar</packaging>
 
-    <name>jpa</name>
+    <name>HibernateSpringBootJoinFetch</name>
     <description>JPA project for Spring Boot</description>
 
     <parent>
         <groupId>org.springframework.boot</groupId>
         <artifactId>spring-boot-starter-parent</artifactId>
-        <version>2.0.5.RELEASE</version>
+        <version>2.1.4.RELEASE</version>
         <relativePath/> <!-- lookup parent from repository -->
     </parent>
 
@@ -57,6 +57,4 @@
             </plugin>
         </plugins>
     </build>
-
-
 </project>

HibernateSpringBootJoinFetch/pom.xml

@@ -0,0 +1,36 @@
+package com.bookstore;
+
+import com.bookstore.entity.Author;
+import com.bookstore.entity.Book;
+import com.bookstore.service.BookstoreService;
+import org.springframework.boot.ApplicationRunner;
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.context.annotation.Bean;
+
+@SpringBootApplication
+public class MainApplication {
+
+    private final BookstoreService bookstoreService;
+
+    public MainApplication(BookstoreService bookstoreService) {
+        this.bookstoreService = bookstoreService;
+    }
+
+    public static void main(String[] args) {
+        SpringApplication.run(MainApplication.class, args);
+    }
+
+    @Bean
+    public ApplicationRunner init() {
+        return args -> {
+
+            Author author = bookstoreService.fetchAuthorWithBooksByName();
+            System.out.println("\nAuthor name: " + author.getName() + " Books: " + author.getBooks() + "\n");
+
+            Book book = bookstoreService.fetchBookWithAuthorByIsbn();
+            System.out.println("\nTitle: " + book.getTitle() + " author: " + book.getAuthor() + "\n");
+
+        };
+    }
+}

HibernateSpringBootJoinFetch/sample 1.png

@@ -0,0 +1,83 @@
+package com.bookstore.entity;
+
+import java.io.Serializable;
+import java.util.ArrayList;
+import java.util.List;
+import javax.persistence.CascadeType;
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+
+@Entity
+public class Author implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    @Id
+    private Long id;
+
+    private String name;
+    private String genre;
+    private int age;
+
+    @OneToMany(cascade = CascadeType.ALL,
+            mappedBy = "author", orphanRemoval = true)
+    private List<Book> books = new ArrayList<>();
+
+    public void addBook(Book book) {
+        this.books.add(book);
+        book.setAuthor(this);
+    }
+
+    public void removeBook(Book book) {
+        book.setAuthor(null);
+        this.books.remove(book);
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getGenre() {
+        return genre;
+    }
+
+    public void setGenre(String genre) {
+        this.genre = genre;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public List<Book> getBooks() {
+        return books;
+    }
+
+    public void setBooks(List<Book> books) {
+        this.books = books;
+    }
+
+    @Override
+    public String toString() {
+        return "Author{" + "id=" + id + ", name=" + name
+                + ", genre=" + genre + ", age=" + age + '}';
+    }
+
+}

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

@@ -0,0 +1,78 @@
+package com.bookstore.entity;
+
+import java.io.Serializable;
+import javax.persistence.Entity;
+import javax.persistence.FetchType;
+import javax.persistence.Id;
+import javax.persistence.JoinColumn;
+import javax.persistence.ManyToOne;
+
+@Entity
+public class Book implements Serializable {
+
+    private static final long serialVersionUID = 1L;
+
+    @Id
+    private Long id;
+
+    private String title;
+    private String isbn;   
+
+    @ManyToOne(fetch = FetchType.LAZY)
+    @JoinColumn(name = "author_id")
+    private Author author;
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public String getIsbn() {
+        return isbn;
+    }
+
+    public void setIsbn(String isbn) {
+        this.isbn = isbn;
+    }
+   
+    public Author getAuthor() {
+        return author;
+    }
+
+    public void setAuthor(Author author) {
+        this.author = author;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (!(obj instanceof Book)) {
+            return false;
+        }
+        return id != null && id.equals(((Book) obj).id);
+    }
+
+    @Override
+    public int hashCode() {
+        return 2021;
+    }
+
+    @Override
+    public String toString() {
+        return "Book{" + "id=" + id + ", title=" + title + ", isbn=" + isbn + '}';
+    }
+   
+}

HibernateSpringBootJoinFetch/src/main/java/com/bookstore/entity/Author.java

@@ -0,0 +1,15 @@
+package com.bookstore.repository;
+
+import com.bookstore.entity.Author;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.stereotype.Repository;
+import org.springframework.transaction.annotation.Transactional;
+
+@Repository
+public interface AuthorRepository extends JpaRepository<Author, Long> {
+
+    @Transactional(readOnly = true)
+    @Query(value = "SELECT a FROM Author a JOIN FETCH a.books WHERE a.name = ?1")
+    Author fetchAuthorWithBooksByName(String name);
+}

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

@@ -0,0 +1,15 @@
+package com.bookstore.repository;
+
+import com.bookstore.entity.Book;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.stereotype.Repository;
+import org.springframework.transaction.annotation.Transactional;
+
+@Repository
+public interface BookRepository extends JpaRepository<Book, Long> {
+
+    @Transactional(readOnly = true)
+    @Query(value = "SELECT b FROM Book b JOIN FETCH b.author WHERE b.isbn = ?1")
+    Book fetchBookWithAuthorByIsbn(String isbn);
+}

HibernateSpringBootJoinFetch/src/main/java/com/bookstore/repository/AuthorRepository.java

@@ -0,0 +1,30 @@
+package com.bookstore.service;
+
+import com.bookstore.repository.AuthorRepository;
+import com.bookstore.repository.BookRepository;
+import com.bookstore.entity.Author;
+import com.bookstore.entity.Book;
+import org.springframework.stereotype.Service;
+
+@Service
+public class BookstoreService {
+
+    private final AuthorRepository authorRepository;
+    private final BookRepository bookRepository;
+
+    public BookstoreService(AuthorRepository authorRepository,
+            BookRepository bookRepository) {
+        this.authorRepository = authorRepository;
+        this.bookRepository = bookRepository;
+    }
+
+    public Author fetchAuthorWithBooksByName() {
+
+        return authorRepository.fetchAuthorWithBooksByName("Joana Nimar");
+    }
+
+    public Book fetchBookWithAuthorByIsbn() {
+
+        return bookRepository.fetchBookWithAuthorByIsbn("002-JN");
+    }
+}