Web Api Request Throws "Error while copying content to a stream."

Question

I'm trying to implement this code example, but get a HttpRequestException - "Error while copying content to a stream." when the ReadAsStringAsync() method is called. The inner exception is "Cannot access a disposed object." I'm using Fiddler to make the request. I don't understand. Can someone explain why I'm getting this exception and offer a solution?

Web Api Method:

public async Task<HttpResponseMessage> Post(HttpRequestMessage request)
{
    try
    {
        var jsonString = await request.Content.ReadAsStringAsync();
    }
    catch (Exception ex)
    {                
        throw;
    }
    return new HttpResponseMessage(HttpStatusCode.Created);
}

Fiddler (POST):

User-Agent: Fiddler
Host: localhost:23567
Content-Length: 18
Content-Type: application/json; charset=utf-8
Body{"Test":1}

Edit:

I have a clue, but need verification. On the Web Api controller, I have an ActionFilterAttribute and in its OnActionExecuting override, there's this line:

public override async void OnActionExecuting(HttpActionContext actionContext)
{
    // omitted code
    actionContext.Request.Content.ReadAsStreamAsync();
}

Could it be that because the Content is read here, it's not available again? If so, how can I make it available in the method? Is the Content here the same as the HttpRequestMessage? This may contain an answer.

Answer 1

Because the controller's ActionFilterAttribute's OnActionExecuting method is calling ReadAsStreamAsync, the Content can't be read again. I changed ReadAsStreamAsync to ReadAsStringAsync and the request's Content is available in the controller. Apparantly, ReadAsStringAsync buffers the Content so it's still available. This link provided the answer.