BAEL-2810: Finished the examples and unit tests. (#6732)

persistence-modules/spring-data-jpa-2/src/main/java/com/baeldung/datajpadelete/entity/Book.java

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+package com.baeldung.datajpadelete.entity;
+
+import javax.persistence.*;
+
+@Entity
+public class Book {
+
+    @Id
+    @GeneratedValue
+    private Long id;
+    private String title;
+
+    @ManyToOne
+    private Category category;
+
+    public Book() {
+    }
+
+    public Book(String title) {
+        this.title = title;
+    }
+
+    public Book(String title, Category category) {
+        this.title = title;
+        this.category = category;
+    }
+
+    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 Category getCategory() {
+        return category;
+    }
+
+    public void setCategory(Category category) {
+        this.category = category;
+    }
+}

persistence-modules/spring-data-jpa-2/src/main/java/com/baeldung/datajpadelete/entity/Category.java

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+package com.baeldung.datajpadelete.entity;
+
+import javax.persistence.*;
+import java.util.List;
+import java.util.stream.Collectors;
+import java.util.stream.Stream;
+
+@Entity
+public class Category {
+
+    @Id
+    @GeneratedValue
+    private Long id;
+    private String name;
+
+    @OneToMany(mappedBy = "category", cascade = CascadeType.ALL, orphanRemoval = true)
+    private List<Book> books;
+
+    public Category() {
+    }
+
+    public Category(String name) {
+        this.name = name;
+    }
+
+    public Category(String name, Book... books) {
+        this.name = name;
+        this.books = Stream.of(books).collect(Collectors.toList());
+        this.books.forEach(x -> x.setCategory(this));
+    }
+
+    public Category(String name, List<Book> books) {
+        this.name = name;
+        this.books = books;
+    }
+
+    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 List<Book> getBooks() {
+        return books;
+    }
+
+    public void setBooks(List<Book> books) {
+        this.books = books;
+    }
+}

persistence-modules/spring-data-jpa-2/src/main/java/com/baeldung/datajpadelete/repository/BookRepository.java

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+package com.baeldung.datajpadelete.repository;
+
+import com.baeldung.datajpadelete.entity.Book;
+import org.springframework.data.jpa.repository.Modifying;
+import org.springframework.data.jpa.repository.Query;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.data.repository.query.Param;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface BookRepository extends CrudRepository<Book, Long> {
+
+    long deleteByTitle(String title);
+
+    @Modifying
+    @Query("delete from Book b where b.title=:title")
+    void deleteBooks(@Param("title") String title);
+
+}

persistence-modules/spring-data-jpa-2/src/main/java/com/baeldung/datajpadelete/repository/CategoryRepository.java

@@ -0,0 +1,9 @@
+package com.baeldung.datajpadelete.repository;
+
+import com.baeldung.datajpadelete.entity.Category;
+import org.springframework.data.repository.CrudRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface CategoryRepository extends CrudRepository<Category, Long> {
+}

persistence-modules/spring-data-jpa-2/src/test/java/com/baeldung/datajpadelete/DeleteFromRepositoryUnitTest.java

@@ -0,0 +1,72 @@
+package com.baeldung.datajpadelete;
+
+import com.baeldung.Application;
+import com.baeldung.datajpadelete.entity.Book;
+import com.baeldung.datajpadelete.repository.BookRepository;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.transaction.annotation.Transactional;
+
+import java.util.Arrays;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = {Application.class})
+public class DeleteFromRepositoryUnitTest {
+
+    @Autowired
+    private BookRepository repository;
+
+    Book book1;
+    Book book2;
+
+    @Before
+    public void setup() {
+        book1 = new Book("The Hobbit");
+        book2 = new Book("All Quiet on the Western Front");
+
+        repository.saveAll(Arrays.asList(book1, book2));
+    }
+
+    @After
+    public void teardown() {
+        repository.deleteAll();
+    }
+
+    @Test
+    public void whenDeleteByIdFromRepository_thenDeletingShouldBeSuccessful() {
+        repository.deleteById(book1.getId());
+
+        assertThat(repository.count() == 1).isTrue();
+    }
+
+    @Test
+    public void whenDeleteAllFromRepository_thenRepositoryShouldBeEmpty() {
+        repository.deleteAll();
+
+        assertThat(repository.count() == 0).isTrue();
+    }
+
+    @Test
+    @Transactional
+    public void whenDeleteFromDerivedQuery_thenDeletingShouldBeSuccessful() {
+        repository.deleteByTitle("The Hobbit");
+
+        assertThat(repository.count() == 1).isTrue();
+    }
+
+    @Test
+    @Transactional
+    public void whenDeleteFromCustomQuery_thenDeletingShouldBeSuccessful() {
+        repository.deleteBooks("The Hobbit");
+
+        assertThat(repository.count() == 1).isTrue();
+    }
+
+}

persistence-modules/spring-data-jpa-2/src/test/java/com/baeldung/datajpadelete/DeleteInRelationshipsUnitTest.java

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+package com.baeldung.datajpadelete;
+
+import com.baeldung.Application;
+import com.baeldung.datajpadelete.entity.Book;
+import com.baeldung.datajpadelete.entity.Category;
+import com.baeldung.datajpadelete.repository.BookRepository;
+import com.baeldung.datajpadelete.repository.CategoryRepository;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = {Application.class})
+public class DeleteInRelationshipsUnitTest {
+
+    @Autowired
+    private BookRepository bookRepository;
+
+    @Autowired
+    private CategoryRepository categoryRepository;
+
+    @Before
+    public void setup() {
+        Book book1 = new Book("The Hobbit");
+        Category category1 = new Category("Cat1", book1);
+        categoryRepository.save(category1);
+
+        Book book2 = new Book("All Quiet on the Western Front");
+        Category category2 = new Category("Cat2", book2);
+        categoryRepository.save(category2);
+    }
+
+    @After
+    public void teardown() {
+        bookRepository.deleteAll();
+        categoryRepository.deleteAll();
+    }
+
+    @Test
+    public void whenDeletingCategories_thenBooksShouldAlsoBeDeleted() {
+        categoryRepository.deleteAll();
+
+        assertThat(bookRepository.count() == 0).isTrue();
+        assertThat(categoryRepository.count() == 0).isTrue();
+    }
+
+    @Test
+    public void whenDeletingBooks_thenCategoriesShouldAlsoBeDeleted() {
+        bookRepository.deleteAll();
+
+        assertThat(bookRepository.count() == 0).isTrue();
+        assertThat(categoryRepository.count() == 2).isTrue();
+    }
+}