Bits of .NET

🛡️ API Error Handling = User Experience

Errors happen. Error handling best practices ensure users understand what went wrong.

📝 Error Response Format

// Success Response
{
    "success": true,
    "data": { ... },
    "message": "Operation completed successfully"
}

// Error Response
{
    "success": false,
    "error": {
        "code": "VALIDATION_001",
        "message": "Invalid input provided",
        "details": [
            {
                "field": "email",
                "message": "Email is required"
            }
        ],
        "timestamp": "2024-01-15T10:00:00Z",
        "requestId": "abc-123-def-456"
    }
}

// HTTP Status Codes
- 200: Success
- 201: Created
- 400: Bad Request
- 401: Unauthorized
- 403: Forbidden
- 404: Not Found
- 409: Conflict
- 422: Unprocessable Entity
- 429: Too Many Requests
- 500: Internal Server Error

🎯 Client-Side Error Handling

// Fetch with Error Handling
async function fetchData(url) {
    try {
        const response = await fetch(url);
        
        if (!response.ok) {
            const error = await response.json();
            throw new APIError(response.status, error);
        }
        
        return await response.json();
    } catch (error) {
        if (error instanceof APIError) {
            handleAPIError(error);
        } else if (error.name === 'AbortError') {
            console.log('Request aborted');
        } else if (error.name === 'TimeoutError') {
            console.log('Request timed out');
        } else {
            console.error('Unknown error:', error);
            showUserError('An unexpected error occurred');
        }
        throw error;
    }
}

// API Error Class
class APIError extends Error {
    constructor(status, data) {
        super(data.error.message);
        this.status = status;
        this.code = data.error.code;
        this.details = data.error.details;
        this.timestamp = data.error.timestamp;
        this.requestId = data.error.requestId;
    }

    getUserMessage() {
        return this.details 
            ? this.details.map(d => d.message).join('; ')
            : this.message;
    }
}

// Global Error Handler
function handleAPIError(error) {
    switch(error.status) {
        case 401:
            redirectToLogin();
            break;
        case 403:
            showUserError('You do not have permission to do this');
            break;
        case 404:
            showUserError('Resource not found');
            break;
        case 429:
            showUserError('Too many requests. Please try again later');
            break;
        case 500:
            showUserError('Server error. Please try again later');
            break;
        default:
            showUserError(error.getUserMessage());
    }
}

💡 Error Handling Tips

• Use consistent error format
• Include helpful error messages
• Provide error codes for debugging
• Log errors for monitoring
• Show user-friendly messages