HttpClient.PostAsync - 为什么会抛出一个ArgumentException

Question

我有其他表单帖子可以正常工作，但由于某种原因，这一个用于引发“System.ArgumentException：值不在预期范围内”。信息。

什么可能是错的？

using (HttpClient client = new HttpClient()) 
{ 
    HttpMultipartFormDataContent data = new HttpMultipartFormDataContent(); 
    data.Add(new HttpStringContent(about ?? String.Empty), "about"); 
    data.Add(new HttpStringContent(displayName ?? String.Empty), "name"); 
    data.Add(new HttpStringContent(email ?? String.Empty), "email"); 
    data.Add(new HttpStringContent(firstName ?? String.Empty), "firstName"); 
    data.Add(new HttpStringContent(lastName ?? String.Empty), "lastName"); 
    data.Add(new HttpStringContent(phone ?? String.Empty), "phone"); 
    data.Add(new HttpStringContent(isPublic.ToString()), "isPublic"); 
    data.Add(new HttpStringContent("true"), "isPrimaryProfile"); 

    Uri uri = new Uri(url, UriKind.Absolute); 
    HttpResponseMessage responseMessage = await client.PostAsync(uri, data); 

} 

Answer 1

啊，显然一个空字符串不是HttpStringContent的有效值。