Setting a Content-Length Header in an ASP.NET 5 Response

Question

TL DR I have an ASP.NET 5 (MVC 6) application and just trying to set the Content-Length HTTP header to avoid a response.

To my surprise, it happens that this is a rather difficult task to perform in ASP.NET 5. Everything works on Kestrel, which from ASP.NET 5 Beta7 supports automatic recording of response responses if the content length is not specified for the response.

There is a similar question here , but the difference is that the OP just wants to calculate the size of the response, while I need to make sure the Content-Length header is sent in the response. Tried a lot of things so far, and the only thing that works is to write your own middleware:

public class WebApiMiddleware {
    RequestDelegate _next;

    public WebApiMiddleware(RequestDelegate next) {
        _next = next;
    }

    public async Task Invoke(HttpContext context) {
         using (var buffer = new MemoryStream()) {
            var response = context.Response;

            var bodyStream = response.Body;
            response.Body = buffer;

            await _next(context);

            response.Headers.Add("Content-Length", new[] { buffer.Length.ToString()});
            buffer.Position = 0;
            await buffer.CopyToAsync(bodyStream);
        }
     }
}

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Answer 1

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