Spring REST Controllers

I have generated a production-ready REST implementation for the Product resource, including validation, DTO mapping, and global error handling.

Spring REST Product Implementation

// ProductDTO.java
@Data
public class ProductDto {
    @NotBlank(message = "Product name is required")
    private String name;
    
    @Positive(message = "Price must be greater than zero")
    private BigDecimal price;
}

// ProductController.java
@RestController
@RequestMapping("/api/products")
@RequiredArgsConstructor
public class ProductController {
    private final ProductService productService;

    @PostMapping
    public ResponseEntity<ProductDto> create(@Valid @RequestBody ProductDto dto) {
        ProductDto created = productService.save(dto);
        URI location = ServletUriComponentsBuilder
            .fromCurrentRequest()
            .path("/{id}")
            .buildAndExpand(created.getId())
            .toUri();
        return ResponseEntity.created(location).body(created);
    }

    @GetMapping("/{id}")
    public ResponseEntity<ProductDto> get(@PathVariable Long id) {
        return productService.findById(id)
            .map(ResponseEntity::ok)
            .orElseThrow(() -> new ResourceNotFoundException("Product " + id + " not found"));
    }
}

// GlobalExceptionHandler.java
@RestControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(ResourceNotFoundException.class)
    public ResponseEntity<ErrorResponse> handleNotFound(ResourceNotFoundException ex) {
        ErrorResponse error = ErrorResponse.builder()
            .code("NOT_FOUND")
            .message(ex.getMessage())
            .timestamp(Instant.now())
            .build();
        return ResponseEntity.status(HttpStatus.NOT_FOUND).body(error);
    }
}

Next steps

1. Add spring-boot-starter-validation to your pom.xml if not present.
2. Implement the ProductService interface and its persistence logic.
3. Define the ErrorResponse record to match your corporate API standards.