title: can't compile - Request.Content.IsMimeMultipartContent() not found
body: <p>I have the following code:</p>
  
  <pre><code>   public class UploadController : ApiController
  {
      DBRepository _repository = new DBRepository();
  
  
      public Task&lt;IEnumerable&lt;FileDesc&gt;&gt; Post()
      {
          string folderName = "UploadedFiles";
          string PATH = HttpContext.Current.Server.MapPath("~/" + folderName);
          PATH = @"c:\www\qqq";
          string rootUrl = Request.RequestUri.AbsoluteUri.Replace(Request.RequestUri.AbsolutePath, String.Empty);
  
  
          if (Request.Content.IsMimeMultipartContent())
          {
              var streamProvider = new CustomMultipartFormDataStreamProvider(PATH);
  
              var task = Request.Content.ReadAsMultipartAsync(streamProvider).ContinueWith&lt;IEnumerable&lt;FileDesc&gt;&gt;(t =&gt;
              {
  
                  if (t.IsFaulted || t.IsCanceled)
                  {
                      throw new HttpResponseException(HttpStatusCode.InternalServerError);
                  }
  
  
                  return fileInfo;
              });
  
              return task;
          }
          else
          {
              throw new HttpResponseException(Request.CreateResponse(HttpStatusCode.NotAcceptable, "This request is not properly formatted"));
          }
  
      }
  }
  </code></pre>
  
  <p>but I got errors:</p>
  
  <blockquote>
    <p>Error 16  'System.Net.Http.HttpContent' does not contain a definition
    for 'IsMimeMultipartContent' and no extension method
    'IsMimeMultipartContent' accepting a first argument of type
    'System.Net.Http.HttpContent' could be found (are you missing a using
    directive or an assembly reference?)  </p>
    
    <p>Error 17  'System.Net.Http.HttpContent' does not contain a definition
    for 'ReadAsMultipartAsync' and no extension method
    'ReadAsMultipartAsync' accepting a first argument of type
    'System.Net.Http.HttpContent' could be found (are you missing a using
    directive or an assembly reference?)  </p>
    
    <p>Error 18  'System.Net.Http.HttpRequestMessage' does not contain a
    definition for 'CreateResponse' and no extension method
    'CreateResponse' accepting a first argument of type
    'System.Net.Http.HttpRequestMessage' could be found (are you missing a
    using directive or an assembly reference?)</p>
  </blockquote>
  
  <p>why?
  I added to project an assembly System.Net.Http.Formatting.dll and have </p>
  
  <pre><code>using System.Net.Http.Formatting;
  </code></pre>
  
  <p>on page <a href="http://msdn.microsoft.com/ru-ru/library/hh834190(v=vs.108).aspx" rel="noreferrer">http://msdn.microsoft.com/ru-ru/library/hh834190(v=vs.108).aspx</a> carefully said, that this ext. method is in System.Net.Http.Formatting (in System.Net.Http.Formatting.dll)
  I tried to compile project under 4.0 and 4.5 - no effect.</p>
  
  <p>PS. I have a solution with the same code, which works perfectly. What can I do?</p>