Get HttpHeaders from HttpRequestException? - asp.net-web-api

Question

I have a Web API, When the incoming request is not valid then the API sends back a HttpStatusCode.BadRequest and API would also add a CorrelationId into Response's HttpHeader. Something like below
public class ValidateRequestAttribute : ActionFilterAttribute
{
public ValidateRequestAttribute()
{
}
public override void OnActionExecuting(ActionExecutingContext context)
{
if (context.ModelState.IsValid == false)
{
context.HttpContext.Response.StatusCode = (int)HttpStatusCode.BadRequest;
context.HttpContext.Response.Headers.Add("x-correlationid", "someid");
context.Result = new ContentResult()
{
Content = "bad request."
};
}
}
}
On client side im using HttpClient to access the API. I am not sure how client would retrieve HttpStatusCode and HttpHeader here. Here is my client code
public bool Process(url)
{
bool result = false;
try
{
Task.Run(async () => await _httpClient.GetStringAsync(url).ConfigureAwait(false)).Result;
}
catch (Exception ex)
{
if(ex is AggregateException)
{
var aggregateException = ex as AggregateException;
foreach(var innerException in aggregateException.InnerExceptions)
{
if (innerException is HttpRequestException)
{
var httpRequestException = innerException as HttpRequestException;
// how do i get StatusCode and HttpHeader values here??
}
}
}
}
return result;
}
I have already gone through SO post here and MSDN article here and also Stephen Cleary's article here
Even though its recommended to make async all the way down, I this case Client and API are both disconnected from each other and client is synchronous. Note that Client's Process method is synchronous method.

Answer 1

Like this:
public bool Process(string url)
{
var result = _httpClient.GetAsync(url).ConfigureAwait(false).GetAwaiter().GetResult();
if (result.StatusCode == HttpStatusCode.BadRequest)
{
IEnumerable<string> values;
if (result.Headers.TryGetValues("x-correlationid", out values))
{
// Should print out "someid"
Console.WriteLine(values.First());
}
}
return result.IsSuccessStatusCode;
}
Also note that doing .GetAwaiter().GetResult(); vs .Result; is recommended since it makes the code easier to work with because it does not throw an AggregateException.
If you want to read the response content as a string just do:
var content = result.Content.ReadAsStringAsync().ConfigureAwait(false).GetAwaiter().GetResult();
If you want to make your code async though you should use the async/await keyword and skip the .GetAwaiter().GetResult();.