Validation added

pom.xml

@@ -61,6 +61,10 @@
             <artifactId>liquibase-core</artifactId>
             <version>${liquibase.version}</version>
         </dependency>
+        <dependency>
+            <groupId>org.hibernate.validator</groupId>
+            <artifactId>hibernate-validator</artifactId>
+        </dependency>
     </dependencies>
 
     <build>

src/main/java/org/bookstore/controller/BookController.java

@@ -1,5 +1,6 @@
 package org.bookstore.controller;
 
+import jakarta.validation.Valid;
 import java.util.List;
 import lombok.RequiredArgsConstructor;
 import org.bookstore.dto.BookDto;
@@ -31,13 +32,13 @@ public BookDto getBookById(@PathVariable Long id) {
     }
 
     @PostMapping
-    public BookDto createBook(@RequestBody CreateBookRequestDto bookRequestDto) {
+    public BookDto createBook(@RequestBody @Valid CreateBookRequestDto bookRequestDto) {
         return bookService.save(bookRequestDto);
     }
 
     @PutMapping("/{id}")
     public void updateBookById(@PathVariable Long id,
-                               @RequestBody CreateBookRequestDto bookRequestDto) {
+                               @RequestBody @Valid CreateBookRequestDto bookRequestDto) {
         bookService.updateBookById(id, bookRequestDto);
     }
 

src/main/java/org/bookstore/dto/CreateBookRequestDto.java

@@ -1,14 +1,21 @@
 package org.bookstore.dto;
 
+import jakarta.validation.constraints.Min;
+import jakarta.validation.constraints.NotNull;
 import java.math.BigDecimal;
 import lombok.Data;
 
 @Data
 public class CreateBookRequestDto {
     private Long id;
+    @NotNull
     private String title;
+    @NotNull
     private String author;
+    @NotNull
     private String isbn;
+    @NotNull
+    @Min(0)
     private BigDecimal price;
     private String description;
     private String coverImage;

src/main/java/org/bookstore/exceptions/GlobalExceptionHandler.java

@@ -0,0 +1,46 @@
+package org.bookstore.exceptions;
+
+import java.time.LocalDateTime;
+import java.util.LinkedHashMap;
+import java.util.List;
+import java.util.Map;
+import java.util.stream.Collectors;
+import org.springframework.http.HttpHeaders;
+import org.springframework.http.HttpStatus;
+import org.springframework.http.HttpStatusCode;
+import org.springframework.http.ResponseEntity;
+import org.springframework.validation.FieldError;
+import org.springframework.validation.ObjectError;
+import org.springframework.web.bind.MethodArgumentNotValidException;
+import org.springframework.web.bind.annotation.ControllerAdvice;
+import org.springframework.web.context.request.WebRequest;
+import org.springframework.web.servlet.mvc.method.annotation.ResponseEntityExceptionHandler;
+
+@ControllerAdvice
+public class GlobalExceptionHandler extends ResponseEntityExceptionHandler {
+    @Override
+    protected ResponseEntity<Object> handleMethodArgumentNotValid(
+            MethodArgumentNotValidException ex,
+            HttpHeaders headers,
+            HttpStatusCode status,
+            WebRequest request) {
+        Map<String, Object> body = new LinkedHashMap<>();
+        body.put("time", LocalDateTime.now());
+        body.put("status", HttpStatus.BAD_REQUEST);
+        List<String> error = ex.getBindingResult().getAllErrors()
+                .stream()
+                .map(this::getErrorMessage)
+                .collect(Collectors.toList());
+        body.put("errors", error);
+        return new ResponseEntity<>(body, headers, status);
+    }
+
+    private String getErrorMessage(ObjectError objectError) {
+        if (objectError instanceof FieldError) {
+            String field = ((FieldError) objectError).getField();
+            String message = objectError.getDefaultMessage();
+            return field + " " + message;
+        }
+        return objectError.getDefaultMessage();
+    }
+}