MVC 4：如何使用“部分验证”技术？

Question

我需要在 MVC 4 上实现“部分验证技术”，正如 this answer 中所报告的那样：

      public class DontValidateEmailAttribute : ActionFilterAttribute 
         {  public override void OnActionExecuting(ActionExecutingContext filterContext) 
                 {
                    var modelState = filterContext.Controller.ViewData.ModelState;     
                    var incomingValues = filterContext.Controller.ValueProvider;    
                    var key = modelState.Keys.Single(x => incomingValues.Equals("Email"));
                    modelState[key].Errors.Clear();  
                  }
          }

但我收到以下编译错误：“'System.Collections.Generic.ICollection<string>' does not contain a definition for 'Single' and no extension method 'Single' accepting a first argument of type 'System.Collections.Generic.ICollection<string>' could be found (are you missing a using directive or an assembly reference?)...”

谢谢

Answer 1

您在顶部缺少using System.Linq？