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What is ActionResult in ASP.NET MVC?

ASP.NET MVC Controllers & Actions Basic 1–2 Yrs2–3 Yrs Conceptual 1 min read

Quick Answer

ActionResult is the base type for what a controller action returns. It represents a deferred command — “render this view”, “return this JSON”, “redirect there”, “send a 404” — that the framework executes after filters run. Helper methods like View(), Json(), RedirectToAction(), NotFound() and Ok() create the specific result types.

ActionResult is the base class for whatever a controller action returns. Instead of writing to the response, the action returns a result object that describes what should happen — render a view, return JSON, redirect, send a 404 — and the framework executes that after the filters have run. You create them with helpers: View(), Json(), RedirectToAction(), NotFound(), Ok(). For the return type I usually use IActionResult when an action has more than one possible outcome, and in Core Web API I use ActionResult<T> so I can return either the object or a status result and still get good Swagger output.

An action doesn't write to the response directly; it returns a result object and the framework executes it. Common types:

  • ViewResult (View(model)) — renders a Razor view.
  • PartialViewResult — renders a partial, for AJAX fragments.
  • JsonResult (Json(data)) — serialises to JSON.
  • RedirectResult / RedirectToActionResult — 302/301 redirect.
  • StatusCodeResult, NotFoundResult, BadRequestResult, OkObjectResult — bare status codes / with a body.
  • FileResult — streams a file.
  • ContentResult — raw string with a content type.

Return type choices:

  • IActionResult — the interface; use when an action can return different result types.
  • ActionResult<T> (Core) — lets you return either T (serialised) or a result like NotFound(), and improves API documentation.
  • A concrete type like ViewResult — fine when there is only one outcome, and slightly clearer.

Practise the whole thread the way an interviewer walks it — each question builds on the last.

  1. What is ASP.NET MVC?
  2. Explain the ASP.NET MVC request life cycle.
  3. What is routing in ASP.NET MVC?
  4. What is ActionResult in ASP.NET MVC?You are here
  5. What is the difference between ViewBag, ViewData and TempData?
  6. What is a strongly typed view in ASP.NET MVC?
  7. How does model validation work in ASP.NET MVC?
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