many-to-many

hibernate-many-to-many/pom.xml

@@ -0,0 +1,62 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+	xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd">
+	<modelVersion>4.0.0</modelVersion>
+	<parent>
+		<groupId>org.springframework.boot</groupId>
+		<artifactId>spring-boot-starter-parent</artifactId>
+		<version>2.3.3.RELEASE</version>
+		<relativePath/> <!-- lookup parent from repository -->
+	</parent>
+	<groupId>ru.sysout</groupId>
+	<artifactId>manytomany</artifactId>
+	<version>0.0.1-SNAPSHOT</version>
+
+
+
+	<properties>
+		<java.version>11</java.version>
+	</properties>
+
+	<dependencies>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-data-jpa</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>com.h2database</groupId>
+			<artifactId>h2</artifactId>
+			<scope>runtime</scope>
+		</dependency>
+		<dependency>
+			<groupId>org.projectlombok</groupId>
+			<artifactId>lombok</artifactId>
+			<optional>true</optional>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-web</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-test</artifactId>
+			<scope>test</scope>
+			<exclusions>
+				<exclusion>
+					<groupId>org.junit.vintage</groupId>
+					<artifactId>junit-vintage-engine</artifactId>
+				</exclusion>
+			</exclusions>
+		</dependency>
+	</dependencies>
+
+	<build>
+		<plugins>
+			<plugin>
+				<groupId>org.springframework.boot</groupId>
+				<artifactId>spring-boot-maven-plugin</artifactId>
+			</plugin>
+		</plugins>
+	</build>
+
+</project>

hibernate-many-to-many/src/main/java/ru/sysout/SpringDataJpaApplication.java

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+package ru.sysout;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class SpringDataJpaApplication {
+
+
+    public static void main(String[] args) {
+        SpringApplication.run(SpringDataJpaApplication.class, args);
+    }
+
+}

hibernate-many-to-many/src/main/java/ru/sysout/dao/AuthorRepository.java

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+package ru.sysout.dao;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import ru.sysout.model.Author;
+
+public interface AuthorRepository extends JpaRepository<Author, Long> {
+    Author findByName(String name);
+}

hibernate-many-to-many/src/main/java/ru/sysout/dao/BookRepository.java

@@ -0,0 +1,8 @@
+package ru.sysout.dao;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import ru.sysout.model.Book;
+
+public interface BookRepository extends JpaRepository<Book, Long> {
+    Book findByName(String name);
+}

hibernate-many-to-many/src/main/java/ru/sysout/model/Author.java

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+package ru.sysout.model;
+
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.*;
+import java.util.HashSet;
+import java.util.Set;
+
+@NoArgsConstructor
+@Data
+@Entity
+public class Author {
+    @Id
+    @GeneratedValue(strategy = GenerationType.SEQUENCE)
+    private Long id;
+    private String name;
+    public Author(String name){
+        this.name=name;
+    }
+    @ManyToMany (cascade = {
+        CascadeType.PERSIST,
+                CascadeType.MERGE
+    })
+    @JoinTable(name = "author_book",
+            joinColumns = @JoinColumn(name = "author_id"),
+            inverseJoinColumns = @JoinColumn(name = "book_id")
+    )
+    private Set<Book> books=new HashSet();
+
+    public void addBook(Book book){
+        this.books.add(book);
+        book.getAuthors().add(this);
+    }
+
+    public void removeBook(Book book){
+        this.books.remove(book);
+        book.getAuthors().remove(this);
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+
+        if (!(o instanceof Author)) return false;
+
+        return id != null && id.equals(((Author) o).getId());
+    }
+
+    @Override
+    public int hashCode() {
+        return 31;
+    }
+}

hibernate-many-to-many/src/main/java/ru/sysout/model/Book.java

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+package ru.sysout.model;
+
+import lombok.Data;
+import lombok.NoArgsConstructor;
+
+import javax.persistence.*;
+import java.util.HashSet;
+import java.util.Set;
+
+@NoArgsConstructor
+@Data
+@Entity
+public class Book {
+    @Id
+    @GeneratedValue(strategy = GenerationType.SEQUENCE)
+    private Long id;
+    private String name;
+
+    @ManyToMany(mappedBy = "books")
+    private Set<Author> authors=new HashSet<>();
+
+    public Book(String name){
+        this.name=name;
+    }
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+
+        if (!(o instanceof Author)) return false;
+
+        return id != null && id.equals(((Book) o).getId());
+    }
+
+    @Override
+    public int hashCode() {
+        return 31;
+    }
+}

hibernate-many-to-many/src/main/resources/application.yml

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+spring:
+  h2:
+    console:
+      enabled: true
+      path: /h2-console
+  datasource:
+     url: jdbc:h2:mem:testdb
+     username: sa
+     password:
+  jpa:
+    show-sql: true
+    hibernate:
+      ddl-auto: create

hibernate-many-to-many/src/test/java/ru/sysout/ManyToManyTest.java

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+package ru.sysout;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
+import org.springframework.test.annotation.Commit;
+import ru.sysout.dao.AuthorRepository;
+import ru.sysout.dao.BookRepository;
+import ru.sysout.model.Author;
+import ru.sysout.model.Book;
+
+@DataJpaTest
+@Commit
+public class ManyToManyTest {
+    @Autowired
+    private AuthorRepository authorRepository;
+    @Autowired
+    private BookRepository bookRepository;
+
+
+    @BeforeEach
+    public void booksShouldBeAdded() {
+        Author author1 = new Author("a1");
+
+        Book b1 = new Book("b1");
+        Book b2 = new Book("b2");
+        author1.addBook(b1);
+        author1.addBook(b2);
+
+        authorRepository.save(author1);
+
+        Author author2 = new Author("a2");
+        author2.addBook(b1);
+        authorRepository.save(author2);
+
+        Assertions.assertEquals(2, authorRepository.count());
+        Assertions.assertEquals(2, bookRepository.count());
+    }
+
+    @Test
+    @DisplayName("при удалении автора из книги с Set должен выполняться один delete-оператор")
+    public void whenDeleteAuthorFromBook_thenOneDeleteStatement() {
+        Author author = authorRepository.findByName("a1");
+        Book book = bookRepository.findByName("b1");
+        author.removeBook(book);
+    }
+}