削除MVC中“添加”和“编辑”的重复代码

    public class User
    {
        private const string NOT_NULL = "不可为空";
        private const string USERNAME_REGULAR = "用户名必须由字母、数字或下划线组成，3-20个字符";

        //------The model type condition ------
        public string ModelType { get; set; } //"add" or "edit"

        //-----------Add------------
        [RequiredIf("ModelType", "add", ErrorMessage = NOT_NULL)]
        [RegularExpression(@"^[0-9a-zA-Z_]{3,20}$", ErrorMessage = USERNAME_REGULAR)]
        [Remote("ValidateUserName","Home",ErrorMessage="用户已经存在")]
        public string UserName_Add{get;set;}

        //-----------Edit-----------
        [RequiredIf("ModelType", "edit", ErrorMessage = NOT_NULL)]
        [RegularExpression(@"^[0-9a-zA-Z_]{3,20}$", ErrorMessage = USERNAME_REGULAR)]
        public string UserName_Edit { get; set; }

        //----------Comm data-------
        [Range(1, 100)]
        public int Age { get; set; }

        public string Descriptions { get; set; }
    }

@model MvcCombinedCode.Models.User

@{
    ViewBag.Title = "AddUser";
    Layout = "~/Views/Shared/_Layout.cshtml";
}

@using (Html.BeginForm())
{
    @Html.HiddenFor(model=>model.ModelType)
    if (Model.ModelType == "add")
    {
    
增加新用户
    
输入用户名
    
@Html.TextBoxFor(model => model.UserName_Add) @Html.ValidationMessageFor(model => model.UserName_Add)

    }
    else
    {
    
编辑用户
    
当前用户
    
@Model.UserName_Edit @Html.HiddenFor(model => model.UserName_Edit)

    }
    
年龄
    
@Html.TextBoxFor(model => model.Age) @Html.ValidationMessageFor(model => model.Age)
    
描述
    
@Html.TextAreaFor(model => model.Descriptions)
    
"submit" />

}