ASP.NET MVC interview questions and answers

I implement ValidationAttribute or IValidatableObject for multi-property rules.

A partial is only markup plus a model you already have.

PRG: post-redirect-get so a refresh does not resubmit the form.

Razor encodes @model values by default.

I inject services through the constructor and register them in the container.

Awaiting EF or HTTP calls frees the thread while I/O runs, which helps throughput under load.

Constraints like {id:int} reject non-integers before the action runs.

Response cache headers or in-memory cache for data.

When a type cannot be constructed from simple names, like a comma-separated set of ids or a custom date format.

I catch unhandled exceptions, log with a correlation id, and return a Problem view or JSON.

Authorize Role covers coarse checks.

I cache ViewComponents, avoid N+1 in each widget, and load below-the-fold bits later.

One action does one use case: bind, call a service, map to a view model, return.

I inject fakes for services and assert the ActionResult type and model.

System.Web is gone, HttpContext is different, and many packages were rewritten.

Model holds data and domain rules.

Routes map URL patterns to controller actions.

Razor mixes HTML with C# using @ syntax to generate pages.

Data annotations on the model plus ModelState.IsValid in the action catch bad input.

Filters run before or after actions for cross-cutting concerns like auth, logging, and caching.