Interview Q&A

Short answer: PIs? Return a structured JSON response with: status → HTTP status code error → Short message details → Optional for debugging { "status": 400, "error": "Bad Request", "details": "Email is required" }

Real-world example (ShopNest)

Creating an order is POST /api/orders → 201 with Location header. Fetching is GET /api/orders/{id} → 200 or 404.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Return a structured JSON response with: status → HTTP status code error → Short message details → Optional details for debugging

Example code

{ "status": 400, "error": "Bad Request", "details": "Email field is required" }

Real-world example (ShopNest)

Creating an order is POST /api/orders → 201 with Location header. Fetching is GET /api/orders/{id} → 200 or 404.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Indicates the requested resource does not exist. Use when resource ID is invalid or missing. Helps clients handle missing data gracefully. Example in ASP.NET Core: var user = db.Users.Find(id);

Example code

if(user == null) return NotFound(new { status=404, error="User not found" });

Real-world example (ShopNest)

Creating an order is POST /api/orders → 201 with Location header. Fetching is GET /api/orders/{id} → 200 or 404.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Use model validation with data annotations: public class UserModel

Example code

{ [Required] [EmailAddress] public string Email { get; set; }
} Return 400 Bad Request with a list of validation errors: { "status": 400, "error": "Validation Failed", "details": ["Email is required", "Password must be at least 6 characters"] }

Real-world example (ShopNest)

Creating an order is POST /api/orders → 201 with Location header. Fetching is GET /api/orders/{id} → 200 or 404.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: PI? Structured logging with libraries like Serilog, NLog, or built-in ILogger. Log requests and responses, including headers and payloads (avoid sensitive info). Use correlation IDs to trace requests across services. Centralize logs using ELK Stack, Seq, or Azure Application Insights. Log different levels: Information, Warning, Error,… Critical. Example……… using ILogger in ASP.NET Core: private readonly…

Explain a bit more

ILogger<MyController> _logger; public MyController(ILogger<MyController> logger) { _logger = logger; } [HttpGet("{id}")] public IActionResult GetUser(int id) { _logger.LogInformation("Fetching user with id {UserId}", id); try { var user = dbContext.Users.Find(id); if (user == null) { _logger.LogWarning("User with id {UserId} not found", id); return NotFound(); } return Ok(user); } catch (Exception ex) { _logger.LogError(ex, "Error fetching user with id {UserId}", id); return StatusCode(500, "Internal Server Error"); } } This covers all core aspects of error handling and debugging for REST APIs. public MyController(ILogger<MyController> logger)

Example code

{
_logger = logger;
} [HttpGet("{id}")] public IActionResult GetUser(int id)
{ _logger.LogInformation("Fetching user with id {UserId}", id); try {
var user = dbContext.Users.Find(id);
if (user == null)
{ _logger.LogWarning("User with id {UserId} not found", id); return NotFound();
}
return Ok(user);
} catch (Exception ex) { _logger.LogError(ex, "Error fetching user with id {UserId}", id); return StatusCode(500, "Internal Server Error");
}
} This covers all core aspects of error handling and debugging for REST APIs.

Real-world example (ShopNest)

Creating an order is POST /api/orders → 201 with Location header. Fetching is GET /api/orders/{id} → 200 or 404.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.

Short answer: Structured logging → Serilog, NLog, or built-in ILogger in ASP.NET Core. Request/response logging for debugging API calls. Correlation IDs to trace requests across microservices. Centralized logging → ELK Stack, Seq, Azure Application Insights. Log errors, warnings, and important info (not sensitive data). Q&A

Example code

Structured logging → Serilog, NLog, or built-in ILogger in ASP.NET Core. Request/response logging for debugging API calls. Correlation IDs to trace requests across microservices. Centralized logging → ELK Stack, Seq, Azure Application Insights. Log errors, warnings, and important info (not sensitive data). Q&A

Real-world example (ShopNest)

Creating an order is POST /api/orders → 201 with Location header. Fetching is GET /api/orders/{id} → 200 or 404.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.