Spring Boot REST API Validation and Large Payload Handling

Request Payload Validation

Spring Boot uses Bean Validation (JSR-380 / Jakarta Validation).

Dependency

spring-boot-starter-validation

Model Validation

public class Product {

    @NotNull
    private String name;

    @Min(1)
    private double price;
}

Controller

@PostMapping("/products")
public Product createProduct(@Valid @RequestBody Product product) {
    return productService.save(product);
}

Common Validation Annotations

Annotation	Purpose
@NotNull	Cannot be null
@NotBlank	Cannot be blank
@Size	Restricts length
@Min, @Max	Numeric range
@Email	Valid email format

Handling Large Request Payloads

Increase Multipart Limits

spring.servlet.multipart.max-file-size=10MB
spring.servlet.multipart.max-request-size=10MB

Handling File Uploads

@PostMapping("/upload")
public String uploadFile(@RequestParam MultipartFile file) {

    fileService.save(file);

    return "File uploaded successfully";
}

Request content type: multipart/form-data.

Stream Large Content

Use InputStream instead of loading the entire payload into memory.

Pagination

Request:

GET /products?page=1&size=20

Repository usage:

Page<Product> products =
    productRepository.findAll(PageRequest.of(0, 10));

Add sorting with Sort, either standalone or combined with pagination:

Sort sort = Sort.by("salary").descending();
productRepository.findAll(sort);

Pageable pageable =
    PageRequest.of(0, 10, Sort.by("salary").descending());

productRepository.findAll(pageable);

Enable Compression

server.compression.enabled=true

Key Takeaways

• @Valid combined with Bean Validation annotations (@NotNull, @Size, @Email, etc.) validates incoming payloads declaratively, without manual if-checks in the controller.
• For large payloads, prefer streaming (InputStream) over loading the full body into memory.
• Page<T> + PageRequest bound results at the repository layer, complementing the ?page=&size= API-level pagination convention.
• Enabling response compression (server.compression.enabled=true) reduces payload size over the wire for large JSON responses.