英文:
Why can an ASP.NET Core action returning an ` ActionResult<IEnumerable<ZapResult>>` return a `BadRequest()` of any object?
问题
I wonder why an ASP.NET Core action returning an ActionResult<IEnumerable<ZapResult>> may return a BadRequest(scan), where scan is an object of a custom user-defined class?
In this case, I don't see any sensible way of converting ZapScan to IEnumerable<ZapResult>.
Indeed, both Ok() and BadRequest() return objects derived from ActionResult (not ActionResult<T>), but in either case everything works fine and JSON is returned to the client:
[HttpGet, FormatFilter]
public ActionResult<IEnumerable<ZapResult>> OnGet([FromQuery] ZapScan scan)
{
return HandleRequest(scan);
}
private ActionResult<IEnumerable<ZapResult>> HandleRequest(ZapScan scan)
{
if (ValidateScan(scan)) {
IEnumerable<ZapResult> zapResults = _zapDispatcher.Dispatch(scan);
return Ok(zapResults);
}
else
{
var clientIp = HttpContext.Request.HttpContext.Connection.RemoteIpAddress;
var requestUrl = UriHelper.GetDisplayUrl(HttpContext.Request);
_logger.LogError("{0}: Invalid request: [{1}] {2} ({3})", MethodBase.GetCurrentMethod().Name, clientIp, requestUrl, scan);
return BadRequest(scan);
}
}
To me it seems like anything can be converted to ActionResult<T>, and that such return type is completely generic?
英文:
I wonder why an ASP.NET Core action returning an ActionResult<IEnumerable<ZapResult>> may return a BadRequest(scan), where scan is an object of a custom user-defined class?
In this case, I don't see any sensible way of converting ZapScan to IEnumerable<ZapResult>.
Indeed, both Ok() and BadRequest() return objects derived from ActionResult (not ActionResult<T>), but in either case everything works fine and JSON is returned to the client:
[HttpGet, FormatFilter]
public ActionResult<IEnumerable<ZapResult>> OnGet([FromQuery] ZapScan scan)
{
return HandleRequest(scan);
}
private ActionResult<IEnumerable<ZapResult>> HandleRequest(ZapScan scan)
{
if (ValidateScan(scan)) {
IEnumerable<ZapResult> zapResults = _zapDispatcher.Dispatch(scan);
return Ok(zapResults);
}
else
{
var clientIp = HttpContext.Request.HttpContext.Connection.RemoteIpAddress;
var requestUrl = UriHelper.GetDisplayUrl(HttpContext.Request);
_logger.LogError("{0}: Invalid request: [{1}] {2} ({3})", MethodBase.GetCurrentMethod().Name, clientIp, requestUrl, scan);
return BadRequest(scan);
}
}
To me it seems like anything can be converted to ActionResult<T>, and that such return type is completely generic?
答案1
得分: 1
BadRequestResult（由BadRequest()返回）派生自ActionResult。
ActionResult<T>可以通过它实现的IConvertToActionResult接口隐式转换为ActionResult。
因此，返回类型是兼容的，这就是为什么它们可以互换使用。
BadRequestResult有一个构造函数，它接受任何object并将其序列化为字符串，然后原样输出给客户端。
英文:
BadRequestResult (returned by BadRequest()) derives from ActionResult.
ActionResult<T> is implicitly convertible to ActionResult (via the IConvertToActionResult interface it implements).
Therefore the return types are compatible which is why they can be used interchangeably.
BadRequestResult has a constructor that takes any object and serializes it to a string that is output as-is to the client.
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