Jpa One To Many Demo with Rest APIs

Author: Rajeev Kumar Singh

jpa-one-to-many-demo/.mvn/wrapper/maven-wrapper.jar

@@ -1,51 +1,13 @@
 package com.example.jpa;
 
-import com.example.jpa.model.Comment;
-import com.example.jpa.model.Post;
-import com.example.jpa.repository.CommentRepository;
-import com.example.jpa.repository.PostRepository;
-import org.springframework.beans.factory.annotation.Autowired;
-import org.springframework.boot.CommandLineRunner;
 import org.springframework.boot.SpringApplication;
 import org.springframework.boot.autoconfigure.SpringBootApplication;
+import org.springframework.data.jpa.repository.config.EnableJpaAuditing;
 
 @SpringBootApplication
-public class JpaOneToManyDemoApplication implements CommandLineRunner {
-
-	@Autowired
-	private PostRepository postRepository;
-
-	@Autowired
-	private CommentRepository commentRepository;
-
+@EnableJpaAuditing
+public class JpaOneToManyDemoApplication {
 	public static void main(String[] args) {
 		SpringApplication.run(JpaOneToManyDemoApplication.class, args);
 	}
-
-	@Override
-	public void run(String... args) throws Exception {
-		// Cleanup Database tables
-		commentRepository.deleteAllInBatch();
-		postRepository.deleteAllInBatch();
-
-		// ======================================
-
-		Post post = new Post("Hibernate One-To-Many Mapping Example",
-				"Learn how to use one to many mapping in hibernate",
-				"Entire Post Content with sample code");
-
-		Comment comment1 = new Comment("Great Post!");
-		comment1.setPost(post);
-
-		Comment comment2 = new Comment("Really helpful Post. Thanks a lot!");
-		comment2.setPost(post);
-
-		post.getComments().add(comment1);
-		post.getComments().add(comment2);
-
-		postRepository.save(post);
-
-		// ======================================
-
-	}
 }

jpa-one-to-many-demo/.mvn/wrapper/maven-wrapper.properties

@@ -0,0 +1,68 @@
+package com.example.jpa.controller;
+
+import com.example.jpa.exception.ResourceNotFoundExcption;
+import com.example.jpa.model.Comment;
+import com.example.jpa.repository.CommentRepository;
+import com.example.jpa.repository.PostRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.PageRequest;
+import org.springframework.data.domain.Pageable;
+import org.springframework.data.domain.Sort;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import javax.validation.Valid;
+import java.util.List;
+
+@RestController
+public class CommentController {
+
+    @Autowired
+    private CommentRepository commentRepository;
+
+    @Autowired
+    private PostRepository postRepository;
+
+    @GetMapping("/posts/{postId}/comments")
+    public Page<Comment> getAllCommentsByPostId(@PathVariable (value = "postId") Long postId,
+                                                Pageable pageable) {
+        return commentRepository.findByPostId(postId, pageable);
+    }
+
+    @PostMapping("/posts/{postId}/comments")
+    public Comment createComment(@PathVariable (value = "postId") Long postId,
+                                 @Valid @RequestBody Comment comment) {
+        return postRepository.findById(postId).map(post -> {
+            comment.setPost(post);
+            return commentRepository.save(comment);
+        }).orElseThrow(() -> new ResourceNotFoundExcption("PostId " + postId + " not found"));
+    }
+
+    @PutMapping("/posts/{postId}/comments/{commentId}")
+    public Comment updateComment(@PathVariable (value = "postId") Long postId,
+                                 @PathVariable (value = "commentId") Long commentId,
+                                 @Valid @RequestBody Comment commentRequest) {
+        if(!postRepository.existsById(postId)) {
+            throw new ResourceNotFoundExcption("PostId " + postId + " not found");
+        }
+
+        return commentRepository.findById(commentId).map(comment -> {
+            comment.setText(commentRequest.getText());
+            return commentRepository.save(comment);
+        }).orElseThrow(() -> new ResourceNotFoundExcption("CommentId " + commentId + "not found"));
+    }
+
+    @DeleteMapping("/posts/{postId}/comments/{commentId}")
+    public ResponseEntity<?> deleteComment(@PathVariable (value = "postId") Long postId,
+                              @PathVariable (value = "commentId") Long commentId) {
+        if(!postRepository.existsById(postId)) {
+            throw new ResourceNotFoundExcption("PostId " + postId + " not found");
+        }
+
+        return commentRepository.findById(commentId).map(comment -> {
+             commentRepository.delete(comment);
+             return ResponseEntity.ok().build();
+        }).orElseThrow(() -> new ResourceNotFoundExcption("CommentId " + commentId + " not found"));
+    }
+}

jpa-one-to-many-demo/src/main/java/com/example/jpa/JpaOneToManyDemoApplication.java

@@ -0,0 +1,49 @@
+package com.example.jpa.controller;
+
+import com.example.jpa.exception.ResourceNotFoundExcption;
+import com.example.jpa.model.Post;
+import com.example.jpa.repository.PostRepository;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
+import org.springframework.http.ResponseEntity;
+import org.springframework.web.bind.annotation.*;
+
+import javax.validation.Valid;
+
+@RestController
+public class PostController {
+
+    @Autowired
+    PostRepository postRepository;
+
+    @GetMapping("/posts")
+    public Page<Post> getAllPosts(Pageable pageable) {
+        return postRepository.findAll(pageable);
+    }
+
+    @PostMapping("/posts")
+    public Post createPost(@Valid @RequestBody Post post) {
+        return postRepository.save(post);
+    }
+
+    @PutMapping("/posts/{postId}")
+    public Post updatePost(@PathVariable Long postId, @Valid @RequestBody Post postRequest) {
+        return postRepository.findById(postId).map(post -> {
+            post.setTitle(postRequest.getTitle());
+            post.setDescription(postRequest.getDescription());
+            post.setContent(postRequest.getContent());
+            return postRepository.save(post);
+        }).orElseThrow(() -> new ResourceNotFoundExcption("PostId " + postId + " not found"));
+    }
+
+
+    @DeleteMapping("/posts/{postId}")
+    public ResponseEntity<?> deletePost(@PathVariable Long postId) {
+        return postRepository.findById(postId).map(post -> {
+            postRepository.delete(post);
+            return ResponseEntity.ok().build();
+        }).orElseThrow(() -> new ResourceNotFoundExcption("PostId " + postId + " not found"));
+    }
+
+}

jpa-one-to-many-demo/src/main/java/com/example/jpa/controller/CommentController.java

@@ -0,0 +1,19 @@
+package com.example.jpa.exception;
+
+import org.springframework.http.HttpStatus;
+import org.springframework.web.bind.annotation.ResponseStatus;
+
+@ResponseStatus(HttpStatus.NOT_FOUND)
+public class ResourceNotFoundExcption extends RuntimeException {
+    public ResourceNotFoundExcption() {
+        super();
+    }
+
+    public ResourceNotFoundExcption(String message) {
+        super(message);
+    }
+
+    public ResourceNotFoundExcption(String message, Throwable cause) {
+        super(message, cause);
+    }
+}

jpa-one-to-many-demo/src/main/java/com/example/jpa/controller/PostController.java

@@ -0,0 +1,45 @@
+package com.example.jpa.model;
+
+import com.fasterxml.jackson.annotation.JsonIgnoreProperties;
+import org.springframework.data.annotation.CreatedDate;
+import org.springframework.data.annotation.LastModifiedDate;
+import org.springframework.data.jpa.domain.support.AuditingEntityListener;
+
+import javax.persistence.*;
+import javax.validation.constraints.NotNull;
+import java.io.Serializable;
+import java.util.Date;
+
+@MappedSuperclass
+@EntityListeners(AuditingEntityListener.class)
+@JsonIgnoreProperties(
+        value = {"createdAt", "updatedAt"},
+        allowGetters = true
+)
+public abstract class AuditModel implements Serializable {
+    @Temporal(TemporalType.TIMESTAMP)
+    @Column(name = "created_at", nullable = false)
+    @CreatedDate
+    private Date createdAt;
+
+    @Temporal(TemporalType.TIMESTAMP)
+    @Column(name = "updated_at", nullable = false)
+    @LastModifiedDate
+    private Date updatedAt;
+
+    public Date getCreatedAt() {
+        return createdAt;
+    }
+
+    public void setCreatedAt(Date createdAt) {
+        this.createdAt = createdAt;
+    }
+
+    public Date getUpdatedAt() {
+        return updatedAt;
+    }
+
+    public void setUpdatedAt(Date updatedAt) {
+        this.updatedAt = updatedAt;
+    }
+}

jpa-one-to-many-demo/src/main/java/com/example/jpa/exception/ResourceNotFoundExcption.java

@@ -1,5 +1,7 @@
 package com.example.jpa.model;
 
+import com.fasterxml.jackson.annotation.JsonIgnore;
+
 import javax.persistence.*;
 import javax.validation.constraints.NotNull;
 
@@ -8,7 +10,7 @@
  */
 @Entity
 @Table(name = "comments")
-public class Comment {
+public class Comment extends AuditModel {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
@@ -19,16 +21,9 @@ public class Comment {
 
     @ManyToOne(fetch = FetchType.LAZY)
     @JoinColumn(name = "post_id", nullable = false)
+    @JsonIgnore
     private Post post;
 
-    public Comment() {
-
-    }
-
-    public Comment(String text) {
-        this.text = text;
-    }
-
     public Long getId() {
         return id;
     }

jpa-one-to-many-demo/src/main/java/com/example/jpa/model/AuditModel.java

@@ -3,14 +3,13 @@
 import javax.persistence.*;
 import javax.validation.constraints.NotNull;
 import javax.validation.constraints.Size;
-import java.util.*;
 
 /**
  * Created by rajeevkumarsingh on 21/11/17.
  */
 @Entity
 @Table(name = "posts")
-public class Post {
+public class Post extends AuditModel {
     @Id
     @GeneratedValue(strategy = GenerationType.IDENTITY)
     private Long id;
@@ -28,31 +27,6 @@ public class Post {
     @Lob
     private String content;
 
-    @NotNull
-    @Temporal(TemporalType.TIMESTAMP)
-    @Column(name = "posted_at")
-    private Date postedAt = new Date();
-
-    @NotNull
-    @Temporal(TemporalType.TIMESTAMP)
-    @Column(name = "last_updated_at")
-    private Date lastUpdatedAt = new Date();
-
-    @OneToMany(cascade = CascadeType.ALL,
-            fetch = FetchType.LAZY,
-            mappedBy = "post")
-    private Set<Comment> comments = new HashSet<>();
-
-    public Post() {
-
-    }
-
-    public Post(String title, String description, String content) {
-        this.title = title;
-        this.description = description;
-        this.content = content;
-    }
-
     public Long getId() {
         return id;
     }
@@ -84,28 +58,4 @@ public String getContent() {
     public void setContent(String content) {
         this.content = content;
     }
-
-    public Date getPostedAt() {
-        return postedAt;
-    }
-
-    public void setPostedAt(Date postedAt) {
-        this.postedAt = postedAt;
-    }
-
-    public Date getLastUpdatedAt() {
-        return lastUpdatedAt;
-    }
-
-    public void setLastUpdatedAt(Date lastUpdatedAt) {
-        this.lastUpdatedAt = lastUpdatedAt;
-    }
-
-    public Set<Comment> getComments() {
-        return comments;
-    }
-
-    public void setComments(Set<Comment> comments) {
-        this.comments = comments;
-    }
 }

jpa-one-to-many-demo/src/main/java/com/example/jpa/model/Comment.java

@@ -1,6 +1,8 @@
 package com.example.jpa.repository;
 
 import com.example.jpa.model.Comment;
+import org.springframework.data.domain.Page;
+import org.springframework.data.domain.Pageable;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.stereotype.Repository;
 
@@ -9,5 +11,5 @@
  */
 @Repository
 public interface CommentRepository extends JpaRepository<Comment, Long> {
-
+    Page<Comment> findByPostId(Long postId, Pageable pageable);
 }