Interview Q&A

Short answer: Razor Pages use handler methods: public class IndexModel : PageModel {

Example code

public void OnGet() { ... }
public IActionResult OnPost() { ... }
} You can use asp-page-handler="Update" for custom methods.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: Inject services into PageModel constructor: public IndexModel(IMyService service) { ... } Also available in Razor views via @inject: @inject ILogger<MyPage> Logger

Real-world example (ShopNest)

ShopNest registers AppDbContext as Scoped and IMemoryCache as Singleton. Putting DbContext in a Singleton causes threading bugs.

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: Reusable libraries that contain Razor views, pages, static files, etc. Share UI components across multiple projects. dotnet new razorclasslib

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: Used to organize large applications into sections (e.g., Admin, Customer). Each Area has its own Controllers/Views/Models. [Area("Admin")] public class DashboardController : Controller { ... }

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: Handled via: ASP.NET Core Middleware WebOptimizer, Gulp, or Webpack Static files in wwwroot/ Enable in Startup.cs: app.UseStaticFiles();

Example code

Handled via: ASP.NET Core Middleware WebOptimizer, Gulp, or Webpack Static files in wwwroot/ Enable in Startup.cs: app.UseStaticFiles();

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: ASP.NET Core supports Razor by default. You can add support for custom view engines by implementing IViewEngine.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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 IStringLocalizer<T> or IViewLocalizer: @inject IViewLocalizer Localizer <h1>@Localizer["Welcome"]</h1> Add resource .resx files for each language.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: Performance: Very similar, both use Razor rendering. Simplicity: Razor Pages have less boilerplate for page-based UIs. Maintainability: Razor Pages better for small apps, MVC better for large, modular apps. Web API (RESTful Services) Web API (RESTful Services)

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: templates) Attribute Routing (Preferred): [Route("api/products")] [ApiController] public class ProductsController : ControllerBase { [HttpGet("{id}")] public IActionResult Get(int id) { ... } } Route Templates: Use placeholders like {id}, constraints like {id:int}. You can also define route prefixes at controller level and use relative routes in actions.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: pplication/vnd.company.v1+json services.AddApiVersioning(options => { options.ReportApiVersions = true; options.AssumeDefaultVersionWhenUnspecified = true; options.DefaultApiVersion = new ApiVersion(1, 0); }); pplication/vnd.company.v1+json services.AddApiVersioning(options => { options.ReportApiVersions = true;… options.AssumeDefaultVersionWhenUnspecified…… = true; options.DefaultApiVersion = new ApiVersion(1, 0);…

Explain a bit more

}); pplication/vnd.company.v1+json services.AddApiVersioning(options => { options.ReportApiVersions = true; options.AssumeDefaultVersionWhenUnspecified = true; options.DefaultApiVersion = new ApiVersion(1, 0); }); pplication/vnd.company.v1+json services.AddApiVersioning(options => { options.ReportApiVersions = true;… options.AssumeDefaultVersionWhenUnspecified = true; options.DefaultApiVersion = new ApiVersion(1, 0); });

Real-world example (ShopNest)

ShopNest registers AppDbContext as Scoped and IMemoryCache as Singleton. Putting DbContext in a Singleton causes threading bugs.

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: media type versioning) Use Microsoft.AspNetCore.Mvc.Versioning package. ✅ Supported methods: URL versioning: /api/v1/products Header versioning: X-API-Version: 1.0 Media Type versioning: Accept: application/vnd.company.v1+json services.AddApiVersioning(options => { options.ReportApiVersions = true;

Example code

options.AssumeDefaultVersionWhenUnspecified = true;
options.DefaultApiVersion = new ApiVersion(1, 0); });

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: ASP.NET Core selects the response format based on the Accept header. JSON is the default. To add XML: services.AddControllers() .AddXmlSerializerFormatters(); Accept: application/xml

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: SP.NET Core infers the source when possible.

Real-world example (ShopNest)

ShopNest registers AppDbContext as Scoped and IMemoryCache as Singleton. Putting DbContext in a Singleton causes threading bugs.

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: For large uploads, use IFormFile, Stream, or read from Request.Body for streaming. For downloads, return FileStreamResult. Enable buffering or streaming to avoid memory overload.

Example code

For large uploads, use IFormFile, Stream, or read from Request.Body for streaming. For downloads, return FileStreamResult. Enable buffering or streaming to avoid memory overload.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: pp.UseExceptionHandler(config => { config.Run(async context => { // Log and return problem details }); }); Or use ProblemDetails for structured error responses.

Explain a bit more

pp.UseExceptionHandler(config => { config.Run(async context => { // Log and return problem details }); }); Or use ProblemDetails for structured error responses. pp.UseExceptionHandler(config => { config.Run(async context => { // Log and return problem details }); }); Or use ProblemDetails for structured error responses. pp.UseExceptionHandler(config => { config.Run(async context => { // Log and return problem details }); }); Or use ProblemDetails for structured error responses.

Real-world example (ShopNest)

ShopNest pipeline order matters: exception handling → HTTPS → auth → authorization → endpoints. Auth must run before protected APIs.

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 UseExceptionHandler middleware or custom ExceptionMiddleware. You can also create a global error handler: app.UseExceptionHandler(config => { config.Run(async context => { // Log and return problem details }); }); Or use ProblemDetails for structured error responses.

Real-world example (ShopNest)

A ShopNest ValidateModelAttribute runs before actions and returns 400 if ModelState is invalid—same rule for every controller.

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 proper status codes: 200 OK (success) 201 Created (on POST) 204 No Content (on DELETE) 400 Bad Request 401 Unauthorized / 403 Forbidden 404 Not Found 500 Internal Server Error return Ok(result);

Example code

return NotFound();
return BadRequest(ModelState);

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: ActionResult<T>: Combines a return value and response code. public ActionResult<Product> Get(int id) { ... } IActionResult: More flexible, returns different result types explicitly. Prefer ActionResult<T> for simpler, strongly-typed APIs.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: ASP.NET Core supports full async/await pattern for IO-bound tasks. [HttpGet] public async Task<ActionResult<Product>> GetAsync(int id) {

Example code

var product = await _repo.GetAsync(id);
return product == null ? NotFound() : Ok(product);
} ✅ Improves scalability and performance.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: NotFound() : Ok(product); ✅ Improves scalability and performance. NotFound() : Ok(product); ✅ Improves scalability and performance. NotFound() : Ok(product); ✅ Improves scalability and performance. NotFound() : Ok(product); ✅ Improves scalability and performance.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: Enable CORS (Cross-Origin Resource Sharing) to allow client apps from different domains: services.AddCors(options => { options.AddPolicy("AllowFrontend", builder => builder.WithOrigins(" .AllowAnyHeader() .AllowAnyMethod()); }); app.UseCors("AllowFrontend");

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: ASP.NET Core doesn't include rate limiting out of the box (pre-.NET 8). Use libraries like: AspNetCoreRateLimit YARP, Azure API Management .NET 8 introduced built-in RateLimiterMiddleware.

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: pp.UseSwagger(); pp.UseSwaggerUI(); Supports: Auto-generated OpenAPI docs Try it out interface Versioning support pp.UseSwagger(); pp.UseSwaggerUI(); Supports: Auto-generated OpenAPI docs Try it out interface Versioning support pp.UseSwagger(); pp.UseSwaggerUI(); Supports: Auto-generated OpenAPI docs Try it out interface Versioning support pp.UseSwagger();… pp.UseSwaggerUI(); Supports: Auto-generated OpenAPI docs…

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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 Swashbuckle.AspNetCore or NSwag for generating Swagger docs. services.AddSwaggerGen(); app.UseSwagger(); app.UseSwaggerUI(); Supports: Auto-generated OpenAPI docs Try it out interface Versioning support

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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: Unit testing: Mock services/repositories using Moq or FakeItEasy. Integration testing: Use WebApplicationFactory<T> + TestServer + HttpClient. var client = _factory.CreateClient();

Example code

var response = await client.GetAsync("/api/products");

Real-world example (ShopNest)

A ShopNest checkout request flows through middleware, hits a minimal API or controller, uses scoped services, and returns ProblemDetails on errors.

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.