解决 Failed to generate the sample for media type 'application/x-www-form-urlencoded'.

 Asp.net MVC WebAPI 生成帮助文档时对于API的参数是自定义类型的会遇到本错误。

API.Areas.HelpPage.HelpPageConfig 的 Register 方法中 可以将以下代码注释去掉以消除该错误。

//// Uncomment the following to use "[0]=foo&[1]=bar" directly as the sample for all actions that support form URL encoded format
            //// and have IEnumerable<string> as the body parameter or return type.
            //config.SetSampleForType("[0]=foo&[1]=bar", new MediaTypeHeaderValue("application/x-www-form-urlencoded"), typeof(IEnumerable<string>));

　　但是针对不同的自定义类型，如果在帮助文档中都返回 "[0]=foo&[1]=bar" 字符串的话 明显是无法将Post的参数一一列出的，而且也无法根据自定义参数的属性类型进行定制。

解决的方法如下：

1. 新建一个基类

public class Parameter
    {
      

        public  void Reg (HttpConfiguration config){
             Assembly _Assembyle = Assembly.GetAssembly(this.GetType());
             List<Type> supportedClass = _Assembyle.GetTypes().Where(t => t.BaseType != null && t.BaseType.Name == "Parameter").ToList();

             foreach (var s in supportedClass)
             {
                 string str = "";
                 PropertyInfo[] ps = s.GetProperties();
                 foreach (var p in ps)
                 {
                     switch (p.PropertyType.Name)
                     {
                         case "Guid":
                             str += p.Name + "=" + Guid.NewGuid().ToString();
                             break;
                         case "int":
                         case "long":
                             str += p.Name + "=1000"  ;
                             break;
                              default:
                             str += p.Name + "=" +p.Name;
                             break;
                     }
                     str += "&";

                     
                 }
                 str=str.TrimEnd('&');
                 config.SetSampleForType(str, new MediaTypeHeaderValue("application/x-www-form-urlencoded"), s);
             }
           

                
        }

2. Post的参数类继承基类

    public class TestResultComponentVersion_body : Parameter
    {   
        /// <summary>
        /// TestResultId
        /// </summary>
        public Guid TestResultId { get; set; }
        /// <summary>
        /// ComponentName
        /// </summary>
        public string ComponentName  { get; set; }
        /// <summary>
        /// ComponentVersion
        /// </summary>
        public string ComponentVersion { get; set; }

    }

3. API.Areas.HelpPage.HelpPageConfig 的 Register 方法中调用Reg方法

 new Parameter().Reg(config);