Request Parameters

@RequestParam

@GetMapping("/products")
public ResponseEntity<List<Product>> getProducts(
        @RequestParam String category,
        @RequestParam(defaultValue = "0") int page,
        @RequestParam(defaultValue = "20") int size,
        @RequestParam(required = false) BigDecimal minPrice) {
    // category is required
    // page defaults to 0
    // minPrice is optional (can be null)
    return ResponseEntity.ok(productService.filter(category, minPrice, page, size));
}

Parameter Binding

Source	Annotation	Example URL
Query parameter	@RequestParam	/products?category=phone
Path variable	@PathVariable	/products/123
Request body	@RequestBody	POST body JSON
Header	@RequestHeader	Authorization: Bearer ...
Cookie	@CookieValue	session=abc123

Required vs Optional

// Required (default)
@RequestParam String name       // 400 if missing

// Optional with default
@RequestParam(defaultValue = "10") int size

// Optional (nullable)
@RequestParam(required = false) String search

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 Parameters 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