[BAEL-6041] add code for cascading delete (#13699)

Co-authored-by: uzma <u.khan@proxymity.io>

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/unidirectionalcascadingdelete/Article.java

@@ -0,0 +1,46 @@
+package com.baeldung.spring.data.persistence.unidirectionalcascadingdelete;
+
+import java.util.HashSet;
+import java.util.Set;
+
+import javax.persistence.CascadeType;
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+import javax.persistence.OneToMany;
+
+@Entity
+public class Article {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private long id;
+    private String name;
+    @OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
+    private Set<Comment> comments = new HashSet<>();
+
+    public Set<Comment> getComments() {
+        return comments;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public void setComments(Set<Comment> comments) {
+        this.comments = comments;
+    }
+}

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/unidirectionalcascadingdelete/ArticleRepository.java

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+package com.baeldung.spring.data.persistence.unidirectionalcascadingdelete;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface ArticleRepository extends JpaRepository<Article, Long> {
+
+}

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/unidirectionalcascadingdelete/ArticleService.java

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+package com.baeldung.spring.data.persistence.unidirectionalcascadingdelete;
+
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Service;
+
+@Service
+public class ArticleService {
+
+    @Autowired
+    private ArticleRepository articleRepository;
+
+    public void deleteArticle(Article article) {
+        articleRepository.delete(article);
+
+    }
+
+}

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/unidirectionalcascadingdelete/CascadingDeleteApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung.spring.data.persistence.unidirectionalcascadingdelete;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class CascadingDeleteApplication {
+    public static void main(String[] args) {
+        SpringApplication.run(CascadingDeleteApplication.class, args);
+    }
+
+}

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/unidirectionalcascadingdelete/Comment.java

@@ -0,0 +1,45 @@
+package com.baeldung.spring.data.persistence.unidirectionalcascadingdelete;
+
+import java.util.Date;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+
+@Entity
+public class Comment {
+
+    @Id
+    @GeneratedValue(strategy = GenerationType.AUTO)
+    private long id;
+
+    private String description;
+    private Date date;
+
+    public void setId(long id) {
+        this.id = id;
+    }
+
+    public void setDescription(String description) {
+        this.description = description;
+    }
+
+    public void setDate(Date total) {
+        this.date = total;
+    }
+
+    public long getId() {
+        return id;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public Date getDate() {
+        return date;
+    }
+
+}
+

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/unidirectionalcascadingdelete/CommentRepository.java

@@ -0,0 +1,8 @@
+package com.baeldung.spring.data.persistence.unidirectionalcascadingdelete;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface CommentRepository extends JpaRepository<Comment, Long> {
+}

persistence-modules/spring-data-jpa-repo-2/src/test/java/com/baeldung/spring/data/persistence/deletionCascading/ArticleRepositoryIntegrationTest.java

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+package com.baeldung.spring.data.persistence.deletionCascading;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.time.Instant;
+import java.time.temporal.ChronoUnit;
+import java.util.Date;
+import java.util.HashSet;
+import java.util.List;
+import java.util.Set;
+
+import javax.transaction.Transactional;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import com.baeldung.spring.data.persistence.unidirectionalcascadingdelete.Article;
+import com.baeldung.spring.data.persistence.unidirectionalcascadingdelete.ArticleRepository;
+import com.baeldung.spring.data.persistence.unidirectionalcascadingdelete.ArticleService;
+import com.baeldung.spring.data.persistence.unidirectionalcascadingdelete.CascadingDeleteApplication;
+import com.baeldung.spring.data.persistence.unidirectionalcascadingdelete.Comment;
+import com.baeldung.spring.data.persistence.unidirectionalcascadingdelete.CommentRepository;
+
+@SpringBootTest(classes = CascadingDeleteApplication.class)
+@Transactional
+public class ArticleRepositoryIntegrationTest {
+
+    @Autowired
+    private ArticleRepository articleRepository;
+
+    @Autowired
+    private CommentRepository commentRepository;
+
+    @Autowired
+    private ArticleService articleService;
+
+    @Test
+    @Transactional
+    public void givenAnArticleAndItsComments_whenDeleteArticle_thenCommentsDeletedAutomatically() {
+
+        Set<Comment> comments = new HashSet<>();
+        Article article = new Article();
+        article.setName("introduction to Spring");
+
+        Comment comment1 = new Comment();
+        comment1.setDescription("Explain types of Autowired");
+        comment1.setDate(Date.from(Instant.now()));
+
+        Comment comment2 = new Comment();
+        comment2.setDescription("Good article");
+        comment2.setDate(Date.from(Instant.now()
+          .minus(10, ChronoUnit.MINUTES)));
+
+        comments.add(comment1);
+        comments.add(comment2);
+
+        article.setComments(comments);
+        articleRepository.save(article);
+
+        List<Article> articles = articleRepository.findAll();
+        assertThat(articles.size()).isEqualTo(1);
+        Article retrivedArticle = articles.get(0);
+
+        List<Comment> fetchedComments = commentRepository.findAll();
+        assertThat(fetchedComments.size()).isEqualTo(2);
+
+        articleService.deleteArticle(retrivedArticle);
+        assertThat(articleRepository.findAll()).isEmpty();
+
+        assertThat(commentRepository.findAll()).isEmpty();
+
+    }
+}
+