如何在POST后使用System.Net.Http.HttpClient来使用AllowAutoRedirect = true

Question

Here is the code to create a client and POST an object. It is my understanding that setting AllowAutoRedirect = true would enable the ability for the client to follow the redirect then do a GET and I would be able to deserialize said object. My testing has proven unsuccessful so far. Is there something that I may have overlooked?

Web API endpoint:

public HttpResponseMessage Post([FromBody] Contact contact) {

    try {
        // Add user

        ...

        var msg = Request.CreateResponse(HttpStatusCode.Created);
        msg.Headers.Location = new Uri(Request.RequestUri + "/" + customer.Person.PersonID);
        return msg;
    } catch (ValidationException tve) {
        var apiError = new ApiResponseMessage { Message = "Invalid contact" };
        foreach (var message in FilterErrors(tve.Messages)) {
            if (message.Contains("required", StringComparison.OrdinalIgnoreCase)) {
                apiError.Errors.Add(new ApiErrorMessage {
                    Code = ErrorCode.RequiredPropertyNotProvided,
                    Message = message
                });
            } else {
                apiError.Errors.Add(new ApiErrorMessage {
                    Code = ErrorCode.PropertyNotValid,
                    Message = message
                });
            }
        }
        return Request.CreateResponse(HttpStatusCode.BadRequest, apiError);
    }
}

Client code:

public Contact Post(Contact contact)
{
    try
    {
        var handler = new HttpClientHandler { AllowAutoRedirect = true};
        using (var client = new HttpClient(handler))
        {
            client.BaseAddress = new Uri(APIServer);
            client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
            client.DefaultRequestHeaders.Add("X-ApiKey", APIKey.ToString());

            var response = client.PostAsJsonAsync("v1/Contacts", contact).Result;
            if (response.IsSuccessStatusCode)
            {
                Log.DebugFormat("Post v1/Contacts => {0} ({1})", response.StatusCode, response.ReasonPhrase);

                var result = JsonConvert.DeserializeObject<Contact>(response.Content.ReadAsStringAsync().Result);
                // This object is null

            }
            else
            {
                Log.ErrorFormat("Post v1/Contacts => {0} ({1})", response.StatusCode, response.ReasonPhrase);    
                var result = JsonConvert.DeserializeObject<ApiMessageResponse>(
                        response.Content.ReadAsStringAsync().Result);                      
            }


        }

    }
    catch (Exception exception)
    {
        Log.Error(exception);
    }

    return null;
}

Wireshark logs.

POST /v1/Contacts HTTP/1.1 (application/json) HTTP/1.1 201 Created Location: http://api01.example.com/v1/Contacts/10135052

and that's it, no GET ( http://api01.example.com/v1/Contacts/10135052 ) after as far as I can tell.

Answer 1

From the log trace you added, it looks like the response from the POST is a 201 (Created); there is no redirect. The response does contain a URL (either in a header or the body, hard to tell) but it will not mean anything special. Your client will need to parse the URL itself and issue the subsequent GET request explicitly.