c# - ASP.NET MVC 4 - 使用 post 方法

Question

在 Visual Studio 2010 中，我使用 ASP.NET MVC 4 创建 Web API 项目，如本示例所示:https://www.youtube.com/watch?v=H9vBxAH4f5E

一切正常 - 我使用 GET 方法成功了，但是当使用 POST 方法时，我遇到了一个问题:

No MediaTypeFormatter is available to read an object of type 'String' from content with media type 'application/x-www-form-urlencoded'.

我的 webapiconfig.cs 看起来像这样:

public static class WebApiConfig
{
    public static void Register(HttpConfiguration config)
    {
        config.Routes.MapHttpRoute(
            name: "DefaultApi",
            routeTemplate: "{controller}/{id}",
            defaults: new { id = RouteParameter.Optional }
        );

        FormUrlEncodedMediaTypeFormatter f;

        config.Formatters.Clear();
        config.Formatters.Add(new JsonMediaTypeFormatter());

        f = new FormUrlEncodedMediaTypeFormatter();
        f.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));

        config.Formatters.Add(f);
        // application/x-www-form-urlencoded ???
    }
}

为什么我遇到了问题:

No MediaTypeFormatter is available to read an object of type 'String' from content with media type 'application/x-www-form-urlencoded'.

完整的错误信息:

Message: "An error has occurred." ExceptionMessage: "No MediaTypeFormatter is available to read an object of type 'String' from content with media type 'application/x-www-form-urlencoded'." ExceptionType: "System.InvalidOperationException" StackTrace: " at System.Net.Http.HttpContentExtensions.ReadAsAsync[T](HttpContent content, Type type, IEnumerable1 formatters, IFormatterLogger formatterLogger) at System.Web.Http.ModelBinding.FormatterParameterBinding.ReadContentAsync(HttpRequestMessage request, Type type, IEnumerable1 formatters, IFormatterLogger formatterLogger) at System.Web.Http.ModelBinding.FormatterParameterBinding.ExecuteBindingAsync(ModelMetadataProvider metadataProvider, HttpActionContext actionContext, CancellationToken cancellationToken) at System.Web.Http.Controllers.HttpActionBinding.<>c__DisplayClass1.b__0(HttpParameterBinding parameterBinder) at System.Linq.Enumerable.WhereSelectArrayIterator2.MoveNext() at System.Threading.Tasks.TaskHelpers.IterateImpl(IEnumerator1 enumerator, CancellationToken cancellationToken)"

请求头:

User-Agent: Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/37.0.2062.103 Safari/537.36
Origin: chrome-extension://hgmloofddffdnphfgcellkdfbfbjeloo
Content-Type: application/x-www-form-urlencoded 
Accept: */*
Accept-Encoding: gzip,deflate
Accept-Language: he-IL,he;q=0.8,en-US;q=0.6,en;q=0.4

响应头:

Cache-Control: no-cache Pragma: no-cache Content-Type: application/json; charset=utf-8 Expires: -1 Server: Microsoft-IIS/8.0 X-AspNet-Version: 4.0.30319 X-Powered-By: ASP.NET Date: Mon, 08 Sep 2014 18:06:10 GMT Content-Length: 1111

我该如何解决这个问题？

谢谢:)

Answer 1

您应该只需要将新的媒体类型添加到支持的格式列表中:

f = new FormUrlEncodedMediaTypeFormatter();
f.SupportedMediaTypes.Add(new MediaTypeHeaderValue("text/html"));
f.SupportedMediaTypes.Add(new MediaTypeHeaderValue("application/x-www-form-urlencoded"));