OWIN Middleware not able to set http status code

问题

I am running WebAPI with just one Middleware and not able to set response HTTP status code.

I am using OnSendingHeaders() and able to add headers and set response body, but status code is not getting set and response always has it set as 200 OK.

I am able to set response status code in ValidateUrl(context) though. Difference is ValidateUrl(context) is called synchronously and OnSendingHeaders() would be called asynchronously after ProcessIncomingRequest() is executed.

Is HTTP status line being sent even before OnSendingHeaders() gets called?

How/where should I set response HTTP status code when incoming request is being processed asynchronously?

public class Startup
{
    public void Configuration(IAppBuilder appBuilder)
    {
        appBuilder.Use(typeof(SampleMiddleware));
    }
}

public class SampleMiddleware : OwinMiddleware
{
    private string _responseBody = null;

    public SampleMiddleware(OwinMiddleware next) : base(next)
    {
    }

    public async override Task Invoke(IOwinContext context)
    {

        if (!ValidateUrl(context))
        {
            return;
        }

        context.Response.OnSendingHeaders(state =>
        {
            var cntxt = (IOwinContext)state;
            SetResponseMessage(cntxt);
        }, context);

        await ProcessIncomingRequest();

        await Next.Invoke(context);
    }

    private void SetResponseMessage(IOwinContext context)
    {
        //Setting status code
        context.Response.StatusCode = 201;

        //Setting headers
        context.Response.Headers.Add("XYZ", new[] { "Value-1" });
        context.Response.Headers.Add("ABC", new[] { "Value-2" });

        //Setting response body
        context.Response.Write(_responseBody);
    }

    private async Task ProcessIncomingRequest()
    {
        // Process request
        //await ProcessingFunc();

        // Set response body
        _responseBody = "Response body based on above processing";
    }

    private bool ValidateUrl(IOwinContext context)
    {
        if (context.Request.Host.ToString().Equals("xyx"))
        {
            return true;
        }
        else
        {
            context.Response.StatusCode = 400;
            context.Response.Write("Bad Request");
            return false;
        }
    }
}

回答1:

Someone promptly replied to my above post and suggested to move OnSendingHeaders after "await ProcessIncomingRequest();". Suggestion worked! Thanks! Strange that reply is not visible any more.

Now I am hitting another issue. When I add Content-Length header in the response, response code isn't getting set and defaulting to 200 OK. Any clue why?

public async override Task Invoke(IOwinContext context)
{
    if (!ValidateUrl(context))
    {
        return;
    }

    await ProcessIncomingRequest();

    context.Response.OnSendingHeaders(state =>
    {
        var cntxt = (IOwinContext)state;
        SetResponseMessage(cntxt);
    }, context);
}

private void SetResponseMessage(IOwinContext context)
{
    //Setting status code
    context.Response.StatusCode = 201;

    //Setting headers
    context.Response.Headers.Add("XYZ", new[] { "Value-1" });
    context.Response.Headers.Add("ABC", new[] { "Value-2" });

    //Status code is not getting set and default to 200 OK when I add Content-Length header
    context.Response.Headers.Add("Content-Length", new[] { string.Format("{0}", _responseBody.Length) });

    //Setting response body
    context.Response.Write(_responseBody);
}

来源：https://stackoverflow.com/questions/55305263/owin-middleware-not-able-to-set-http-status-code

标签

ASP.NET

asp.net-web-api2

owin

owin-middleware