asp.net-core – 什么应该是WEB API Action Method的返回类型？

If I want [the] client to do content negotiation then what should be the return type of the API action method?

要进行内容协商,请返回Task< ObjectResult>或任务< MyPoco>.

框架自动将POCO包装在ObjectResult中;因此,两个选项都是等价的,并且都将遵循HTTP Accept标头.您还将通过返回实现ObjectResult的任何结果来获得内容协商,例如OkObjectResult.

If I want [the] method to always return data in JSON format then what should be [the] return type of the API action method?

要始终返回JSON,请返回Task< JsonResult> (或使用[Produces]过滤器).

另见：https://docs.asp.net/en/latest/mvc/models/formatting.html#content-negotiation

[S]o I am assuming then IActionResult is only used for MVC controller?

IActionResult是Controller返回的所有结果的合同.如果您的操作的签名具有IActionResult返回类型,那么您的操作的方法体可以返回任何结果类型,因为它们都实现了IActionResult接口.这是继承层次结构.

IActionResult
  ActionResult
    ChallengeResult 
    ContentResult 
    EmptyResult 
    FileResult 
      FileContentResult 
      FileStreamResult 
      PhysicalFileResult 
      VirtualFileResult 
    ForbidResult 
    LocalRedirectResult 
    ObjectResult
      CreatedAtActionResult 
      CreatedAtRouteResult 
      CreatedResult 
      BadRequestObjectResult 
      NotFoundObjectResult 
      OkObjectResult 
    RedirectResult 
    RedirectToActionResult 
    RedirectToRouteResult 
    SignInResult 
    SignOutResult 
    StatusCodeResult 
      NoContentResult 
      NotFoundResult 
      OkResult 
      UnauthorizedResult 
      UnsupportedMediaTypeResult 
      BadRequestResult

另见：https://github.com/aspnet/Mvc/tree/dev/src/Microsoft.AspNetCore.Mvc.Core