Web API“请求”为空

Question

我正在尝试使用“请求”从POST Web API操作返回HttpResponseException ：

throw new HttpResponseException(Request.CreateErrorResponse(HttpStatusCode.NotFound, "File not in a correct size"));

这样做的时候，我得到的Value cannot be null. Parameter name: request Value cannot be null. Parameter name: request 。

基本上 - 请求为空。

我错过了什么？

谢谢

Answer 1

我在我的ApiController中发现我的Request对象为null，因为我在另一个中嵌套了一个ApiController调用。 因此，第二个嵌套的ApiController从未被初始化。 您无法手动初始化它，但您可以利用Request对象上的setter从包装器传递到嵌套的ApiController。 下面是一个模型，在我的实际代码中修复了我的Request.CreateErrorResponse（...）错误。

public class WrapperController : ApiController
{
    // POST api/wrapper
    public void Post(ComplexWithChild value)
    {
        var other = value.otherdata;

        var childcontroller = new ChildController();
        childcontroller.Post(value.child); // ChildController is not initialized, and has null Request
        /*inside ChildController...// causes null reference exception due to null Request
            Request.CreateErrorResponse(HttpStatusCode.BadRequest, "my message"); 
        */

        childcontroller.Request = this.Request;
        childcontroller.Post(value.child); // ChildController uses same Request
        /*inside ChildController...// this works now
            Request.CreateErrorResponse(HttpStatusCode.BadRequest, "my message"); 
        */
    }
}

public class ChildController : ApiController
{
    public void Post(Child value)
    {
        throw new HttpResponseException(Request.CreateErrorResponse(HttpStatusCode.BadRequest, "my message"));
    }
}

Answer 2

用这个：

HttpResponseMessage message = new HttpResponseMessage(HttpStatusCode.InternalServerError);
message.Content = new ObjectContent(typeof(MessageResponse), "Invalid Size", GlobalConfiguration.Configuration.Formatters.JsonFormatter);
throw new HttpResponseException(message);

注意：您可以使用您可能要为用户返回的任何对象更改“无效大小”。 例如：

public ErrorMessage
{
     public string Error;
     public int ErrorCode;
}

ErrorMessage msg = new ErrorMessage();
msg.Error = "Invalid Size";
msg.ErrorCode = 500;

HttpResponseMessage message = new HttpResponseMessage(HttpStatusCode.InternalServerError);
message.Content = new ObjectContent(typeof(MessageResponse), msg, GlobalConfiguration.Configuration.Formatters.JsonFormatter);
throw new HttpResponseException(message);

Answer 3

像@ DavB.cs这样嵌套ApiControllers的人的另一个解决方案是：

public class ParentController : ApiController
{
    public IHttpActionResult Foo()
    {
       ChildRepository.Foo();
       return Ok(...);
    }
}

public class ChildRepository : ApiController
{
    public HttpResponseMessage Foo()
    {
        // Do something
        return Request.CreateResponse(...);
    }
}

只是简单地从ParentController传递Request：

public class ParentController : ApiController
    {
        public IHttpActionResult Foo()
        {
           ChildRepository.Foo(Request);
           return Ok(...);
        }
    }

    public class ChildRepository
    {
        public HttpResponseMessage Foo(HttpRequestMessage request)
        {
            // Do something
            return request.CreateResponse(...);
        }
    }

请求来自ApiController。 这将使您超过“请求为空”问题。

希望这有助于某人。

Answer 4

nizari的答案是正确的，但我最终使用以下内容：

throw new HttpResponseException(new HttpResponseMessage(HttpStatusCode.InternalServerError)
                    {
                        Content = new StringContent("Invalid image dimensions. Image file must be " + image.Width + "x" + image.Height + "px"),
                        StatusCode = HttpStatusCode.Forbidden
                    });

并使用jqXHR.responseText访问客户端上的内容

感谢大家！

Answer 5

扩展nizari的答案，这是我为了包含ErrorMessage对象列表所做的事情：

IEnumerable errorList = new List<ErrorMessage>();

// ...

var error = new HttpError( "There were errors." ) 
{
    { "Errors", errorList }
};

var message = new HttpResponseMessage( HttpStatusCode.BadRequest )
{
    Content = new ObjectContent<HttpError>( error, GlobalConfiguration.Configuration.Formatters.JsonFormatter )
};

throw new HttpResponseException( message );

Answer 6

您必须创建System.Net.Http.HttpRequestMessage的新实例。 以下会奏效

var request = new HttpRequestMessage();
var response = request.CreateErrorResponse(HttpStatusCode.NotFound, "File not in a correct size");

throw new HttpResponseException(response);

Answer 7

HttpResponseMessage message = new  HttpResponseMessage(HttpStatusCode.InternalServerError); 
message.Content = new ObjectContent(typeof(MessageResponse),
                                    "Invalid Size",
                                    GlobalConfiguration.Configuration.Formatters.JsonFormatter); 
throw new HttpResponseException(message);