Backend Development Patterns

Source: affaan-m/everything-claude-code

API Design Patterns

RESTful API Structure

• •Resource-based URLs with standard HTTP methods (GET, POST, PUT, PATCH, DELETE)
• •Query parameters for filtering, sorting, and pagination

Repository Pattern

Abstract data access logic by implementing interfaces that separate data access concerns from business logic.

public interface BookingRepository extends JpaRepository<Booking, Long> {
    List<Booking> findByUserId(Long userId);
}

Service Layer Pattern

Isolate business logic in service classes that coordinate with repositories.

@Service
public class BookingService {
    private final BookingRepository bookingRepository;
    // Business logic here
}

Database Patterns

Query Optimization

• •Select only needed columns (avoid SELECT *)
• •Use projections for read-only queries

N+1 Query Prevention

• •Use @EntityGraph or JOIN FETCH
• •Batch fetch related entities

Transaction Pattern

@Transactional
public void createBooking(BookingRequest request) {
    // Atomic operations with automatic rollback on error
}

Caching Strategies

Cache-Aside Pattern

1. •Check cache first
2. •On miss, query database
3. •Populate cache for subsequent requests

Error Handling

Centralized Error Handler

@RestControllerAdvice
public class GlobalExceptionHandler {
    @ExceptionHandler(BusinessException.class)
    public ResponseEntity<ErrorResponse> handleBusinessException(BusinessException e) {
        // Unified error response
    }
}

Retry with Exponential Backoff

For transient failures: 1s -> 2s -> 4s delays

Authentication & Authorization

JWT Validation

• •Verify tokens with shared secrets
• •Include user identity and roles in payload

Role-Based Access Control

@PreAuthorize("hasRole('HOST')")
public void cancelBooking(Long bookingId) { }

Rate Limiting

Prevent request flooding (e.g., 100 requests/minute per user)

Logging & Monitoring

Structured logging with context (user IDs, request IDs, timestamps)