仅在用户完成输入数据时调用远程操作方法

Question

我一直在研究MVC4应用程序，我正在使用Remote Data-Annotation来检查UserName是否已存在于DB中。但我的问题是，当我在TextBox中输入第一个字符时，它调用JSON方法，并且对于每个字符插入，它将调用JSON方法，但我看的是，它应该仅在用户完成将TextName输入TextBox时执行JSON

这是我的类，我用Remote DataAnnotation创建了对象

public class Student
{
        [Display(Name = "User Name")]
        [Required(ErrorMessage = "Please enter {0}")]
        [StringLength(100)] //If i give minLength here as 3 then after entering 3 characters it is going to call JSON Method which i don't want so i removed minLength Attribute
        [Remote("IsAvailable", "Home", ErrorMessage = "{0} already in use!")]
        public string UserName { get; set; }
}

这是我家庭控制器中的JSON方法，我正在检查用户名

public JsonResult IsAvailable(string UserName)
{
        bool blnResult = false;
        if (UserName != null)
        {
            blnResult = !objDBContext.Student.Any(X => X.UserName == UserName);
        }
        return Json(blnResult, JsonRequestBehavior.AllowGet);
}

我的视图很容易输入用户名

<div class="form-group col-lg-4">
                    @Html.LabelFor(model => model.UserName, new { @class = "control-label" })
                    <div>
                        @Html.TextBoxFor(model => model.UserName, new { @class = "form-control", maxlength = "100" })
                        @Html.ValidationMessageFor(model => model.UserName, "*")
                    </div>
                </div>

感谢大家提供有价值的反馈!!