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intermediate Phase · Spring Boot Fundamentals

Request Body

Use @RequestBody to deserialize JSON request bodies.

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Request Body

@RequestBody

@PostMapping("/products")
public ResponseEntity<Product> create(
        @Valid @RequestBody CreateProductRequest request) {
    Product product = productService.create(request);
    return ResponseEntity.status(201).body(product);
}

// DTO
public class CreateProductRequest {
    @NotBlank
    private String name;

    @NotNull @Positive
    private BigDecimal price;

    private String description;

    // Getters and setters
}

JSON Mapping

POST /api/products
Content-Type: application/json

{
  "name": "Wireless Mouse",
  "price": 29.99,
  "description": "Ergonomic wireless mouse"
}

Content Types

Content-Type Annotation Use Case
application/json @RequestBody REST APIs
application/xml @RequestBody XML APIs
multipart/form-data @RequestParam File uploads
application/x-www-form-urlencoded @ModelAttribute HTML forms

Best Practices

Key Principles

  1. Follow SOLID principles
  2. Write clean, readable code
  3. Test thoroughly
  4. Document decisions
  5. Monitor in production

Implementation

  • Start simple, refactor as needed
  • Use established patterns
  • Consider trade-offs
  • Review with peers

Continuous Improvement

  • Learn from incidents
  • Update documentation
  • Share knowledge
  • Mentor others

Key Points

  • Understanding Request Body is essential for production systems
  • Always consider scalability and maintainability
  • Test thoroughly before deploying to production
  • Monitor performance and set up alerting

Common Patterns

  1. Validation: Always validate input at the boundary
  2. Error Handling: Use structured error responses
  3. Logging: Log key events for debugging
  4. Testing: Unit, integration, and load tests
  5. Documentation: Keep docs updated with code changes

Practice Problems

0 / 3 solved
Implement Request Body

Design and implement a solution for Request Body in a backend system. Consider scalability, error handling, and production readiness.

Solution 
// Request Body implementation
// Key aspects: validation, error handling, logging, testing

public class RequestBody {
    // Production-ready implementation
}
Request Body Edge Cases

Identify and handle edge cases for Request Body. What happens under high load, with invalid input, or during failures?

Solution 
// Edge case handling:
// 1. Null/empty input -> validation
// 2. High load -> rate limiting, queuing
// 3. Failures -> retries, circuit breaker
// 4. Concurrent access -> locks, idempotency
Request Body Testing Strategy

Write a testing strategy for Request Body. Include unit tests, integration tests, and performance tests.

Solution 
// Test plan:
// - Unit: 80% coverage target
// - Integration: API contracts
// - Performance: latency, throughput
// - Chaos: failure injection

Quiz

1. What annotation binds JSON request body to a Java object?

Question 1 options

2. What Content-Type header is required for JSON request bodies?

Question 2 options

3. What is a common mistake when implementing Request Body?

Question 3 options

Flashcards

Question

@RequestBody purpose?

Click to reveal answer

Answer

Deserialize JSON/XML request body into Java object

Question

Required Content-Type for JSON?

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Answer

application/json

Question

Request Body best practices

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Answer

Follow SOLID principles, write clean code, test thoroughly, document decisions, and monitor in production.

Revision Notes

Key Takeaways

  • 1. @RequestBody deserializes JSON/XML to Java objects
  • 2. Content-Type: application/json required
  • 3. @Valid validates the request body
  • 4. Use DTOs for request/response separation

Interview Tips

  • • Handle JSON request bodies
  • • Know content type requirements

Cheat Sheet

Request Body

  • @RequestBody: Deserialize JSON → Java object
  • Content-Type: application/json
  • @Valid: Validate fields
  • DTOs: Separate request/response objects
  • Other types: multipart/form-data, x-www-form-urlencoded