ASP.NET Core MVC Interview Question #6

What is IActionResult in ASP.NET Core MVC?

MVC Fundamentals, Controllers, Views & Routing Junior Beginner

Quick Interview Answer

IActionResult is an abstraction representing the result of an MVC action. Different implementations describe different HTTP responses, including ViewResult, RedirectToActionResult, NotFoundResult, FileResult, JsonResult, and ContentResult.

Detailed Explanation

Using IActionResult is useful when an action may return different result types depending on conditions. ASP.NET Core also supports ActionResult<T> primarily in API-style scenarios and allows actions to return certain concrete types directly.

Code Example

public IActionResult Details(int id)
{
    if (id <= 0)
        return BadRequest();

    return View();
}