adding relationships example

Author: springframeworkguru

src/main/java/guru/springframework/spring6webapp/domain/Author.java

@@ -1,9 +1,8 @@
 package guru.springframework.spring6webapp.domain;
 
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
+import jakarta.persistence.*;
+
+import java.util.Set;
 
 /**
  * Created by jt, Spring Framework Guru.
@@ -17,6 +16,17 @@ public class Author {
     private String firstName;
     private String lastName;
 
+    @ManyToMany(mappedBy = "authors")
+    private Set<Book> books;
+
+    public Set<Book> getBooks() {
+        return books;
+    }
+
+    public void setBooks(Set<Book> books) {
+        this.books = books;
+    }
+
     public Long getId() {
         return id;
     }

src/main/java/guru/springframework/spring6webapp/domain/Book.java

@@ -1,9 +1,8 @@
 package guru.springframework.spring6webapp.domain;
 
-import jakarta.persistence.Entity;
-import jakarta.persistence.GeneratedValue;
-import jakarta.persistence.GenerationType;
-import jakarta.persistence.Id;
+import jakarta.persistence.*;
+
+import java.util.Set;
 
 /**
  * Created by jt, Spring Framework Guru.
@@ -17,6 +16,19 @@ public class Book {
     private String title;
     private String isbn;
 
+    @ManyToMany
+    @JoinTable(name = "author_book", joinColumns = @JoinColumn(name = "book_id"),
+        inverseJoinColumns = @JoinColumn(name = "author_id"))
+    private Set<Author> authors;
+
+    public Set<Author> getAuthors() {
+        return authors;
+    }
+
+    public void setAuthors(Set<Author> authors) {
+        this.authors = authors;
+    }
+
     public Long getId() {
         return id;
     }