Adding validation (fixed)

pom.xml

@@ -49,6 +49,20 @@
 			<groupId>org.postgresql</groupId>
 			<artifactId>postgresql</artifactId>
 		</dependency>
+		<dependency>
+			<groupId>org.springframework.boot</groupId>
+			<artifactId>spring-boot-starter-validation</artifactId>
+		</dependency>
+		<dependency>
+			<groupId>jakarta.validation</groupId>
+			<artifactId>jakarta.validation-api</artifactId>
+			<version>2.0.2</version>
+		</dependency>
+		<dependency>
+			<groupId>org.springframework</groupId>
+			<artifactId>spring-web</artifactId>
+			<version>5.3.10</version>
+		</dependency>
 	</dependencies>
 	<build>
 		<plugins>

src/main/java/com/example/blog/controller/PostController.java

@@ -6,10 +6,16 @@
 import com.example.blog.model.Post;
 import com.example.blog.repository.PostRepository;
 import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.http.HttpStatus;
 import org.springframework.http.ResponseEntity;
+import org.springframework.validation.FieldError;
+import org.springframework.web.bind.MethodArgumentNotValidException;
 import org.springframework.web.bind.annotation.*;
 
+import javax.validation.Valid;
+import java.util.HashMap;
 import java.util.List;
+import java.util.Map;
 
 @RestController
 @RequestMapping("/posts")
@@ -25,7 +31,7 @@ public List<Post> getAllPosts() {
 
     // Create a new Post
     @PostMapping
-    public Post createPost(@RequestBody Post post) {
+    public Post createPost(@Valid @RequestBody Post post) {
         return postRepository.save(post);
     }
 
@@ -39,5 +45,14 @@ public ResponseEntity<Post> getPostById(@PathVariable(value = "id") Long postId)
         return ResponseEntity.ok().body(post);
     }
 
-    // Other CRUD methods omitted for brevity.
+    @ExceptionHandler(MethodArgumentNotValidException.class)
+    public ResponseEntity<Object> handleValidationExceptions(MethodArgumentNotValidException ex) {
+        Map<String, String> errors = new HashMap<>();
+        ex.getBindingResult().getAllErrors().forEach((error) -> {
+            String fieldName = ((FieldError) error).getField();
+            String errorMessage = error.getDefaultMessage();
+            errors.put(fieldName, errorMessage);
+        });
+        return new ResponseEntity<>(errors, HttpStatus.BAD_REQUEST);
+    }
 }

src/main/java/com/example/blog/model/Post.java

@@ -6,14 +6,16 @@
 import javax.persistence.GeneratedValue;
 import javax.persistence.GenerationType;
 import javax.persistence.Id;
-import java.util.Objects;
+import javax.validation.constraints.NotBlank;
 
 @Entity
 public class Post {
     @Id
     @GeneratedValue(strategy = GenerationType.AUTO)
     private Long id;
+    @NotBlank(message = "Title cannot be empty")
     private String title;
+    @NotBlank(message = "Body cannot be empty")
     private String body;
     private int views;