使用PostAsync，HttpClient＆amp; C调用来自C＃Metro UI Client的MVC4 WebAPI方法JSON

Question

我使用MVC4中的新WebAPI功能创建了一个方法，并让它在Azure上运行。该方法要求您发布一个包含Username和Password属性的简单LoginModel对象。是的，我计划在经过这个减速带后再进一步确保这个:-)然后该方法以Json格式响应一个对象：

如果我在请求标头中包含“Content-Type：application / json”，我可以使用Fiddler成功调用此方法。它返回200，我可以进入Fiddler Inspector并查看Json响应对象就好了：

但是，我在使用C＃/ XAML从Windows8中的MetroUI应用程序调用此相同方法时遇到问题。我开始在C＃中使用HttpClient和新的Async概念，无论我如何格式化我的Post调用（即使明确地调用我希望Content-Type为“application / json”）Fiddler返回500错误并声明该尝试使用的是Content-Type：“text / html”。我相信这是问题的根源：

为了发布这个方法并找回Json对象，我已经尝试了一切可能的想法，这是我最近的尝试：

HttpClient client = new HttpClient();
        client.DefaultRequestHeaders.Accept.Add(new MediaTypeWithQualityHeaderValue("application/json"));
        HttpContent content = new StringContent(@"{ ""Username"": """ + Username.Text + @", ""Password"": """ + Password.Text + @"""}");

        client.PostAsync("http://myapi.com/authentication", content).ContinueWith(result =>
        {
            var response = result.Result;

            response.EnsureSuccessStatusCode();
        });

这导致500错误，Content-Type设置为“text / html”

这是另一次失败的尝试：

HttpClient httpClient = new HttpClient();
HttpResponseMessage response = await httpClient.PostAsync("http://myapi.com/authentication", new StringContent(@"{ ""Username"": """ + Username.Text + @", ""Password"": """ + Password.Text + @"""}", Encoding.UTF8, "application/json"));
string statusCode = response.StatusCode.ToString();

有人能指出我正确的方向吗？

根据Nemesv的建议，尝试了以下代码：

HttpClient httpClient = new HttpClient();
        HttpContent content = new StringContent(@"{ ""Username"": """ + Username.Text + @", ""Password"": """ + Password.Text + @"""}");
        content.Headers.ContentType = new MediaTypeHeaderValue("application/json");


        HttpResponseMessage response = await httpClient.PostAsync("http://webapi.com/authentication", content);

        string statusCode = response.StatusCode.ToString();
        response.EnsureSuccessStatusCode();

它现在在我的请求标题中显示“application / json”，但仍然在Web Session中显示“text / html”：

Answer 1

尝试此操作以设置Headers.ContentType：

HttpClient httpClient = new HttpClient();
HttpContent content = new StringContent(@"{ ""Username"": """ + "etc." + @"""}");
content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
HttpResponseMessage response = 
    await httpClient.PostAsync("http://myapi.com/authentication", content);
string statusCode = response.StatusCode.ToString();

Answer 2

有一些遗漏尝试这是有效的。

UserLoginModel user = new UserLoginModel { Login = "username", Password = "password" };
string json = Newtonsoft.Json.JsonConvert.SerializeObject(user);
HttpContent content = new StringContent(json);
content.Headers.ContentType = new MediaTypeHeaderValue("application/json");
HttpClient client = new HttpClient();
client.BaseAddress = new Uri("http://localhost:1066/api/");
HttpResponseMessage response = client.PostAsync("Authenticate", content).Result;

if (response.IsSuccessStatusCode)
{
  var result = response.Content.ReadAsAsync<ResultModel>().Result;
}
else
{
  return string.Empty;
}