C# Html.DropDownList的验证和htmlAttributes参数

下面允许您指定一个htmlAttribute，以获得添加到项目的其他html属性

不工作：仍然为空

string className = Validation.ClassFor("vehicleId").ToString();
var htmlAttributes = new { id = "vehicleSelectControl", 
                        style = "font-size:24px;",
                        @class = className
                        };

不起作用：仍然为空，不应为空

string className = (String.IsNullOrEmpty(Validation.ClassFor("vehicleId").ToString())) ? "" : Validation.ClassFor("vehicleId").ToString();

var htmlAttributes = new { id = "vehicleSelectControl", 
                        style = "font-size:24px;",
                        @class = className
                        };

我应该放弃，还是有办法通过验证来设计我的样式

var htmlAttributes = new { id = "vehicleSelectControl", 
                        style = "font-size:24px;",
                        @class = Validation.ClassFor("vehicleId").ToString()

string className = Validation.ClassFor("vehicleId").ToString();
var htmlAttributes = new { id = "vehicleSelectControl", 
                        style = "font-size:24px;",
                        @class = className
                        };

string className = (String.IsNullOrEmpty(Validation.ClassFor("vehicleId").ToString())) ? "" : Validation.ClassFor("vehicleId").ToString();

var htmlAttributes = new { id = "vehicleSelectControl", 
                        style = "font-size:24px;",
                        @class = className
                        };