CusBusInfo.cs

        [Key]
        [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        public int Id { get; set; }

        [Display(Name = "業務夥伴程式碼")]
        [Required(ErrorMessage = "業務夥伴程式碼不能為空！")]
        [Index("IX_CusBusInfor_Key", IsUnique = true, Order = 1)]
        [MaxLength(20)]
        [System.Web.Mvc.Remote("GetIsUse", "CusBusInfos", AdditionalFields = "Id", HttpMethod = "post", ErrorMessage = "業務夥伴程式碼已存在")]
        public string EnterpriseId { get; set; }

HttpMethod :xhr傳送請求 模式：post，get

AdditionalFields：需要額外拋到後臺的欄位，沒有的話，預設就欄位本身

HTML頁面

需要引用這2個JS檔案（或者在建試圖的時候勾選：引用指令碼庫）
<script src="~/Scripts/jquery.validate.min.js"></script>
<script src="~/Scripts/jquery.validate.unobtrusive.min.js"></script>

<div class="form-group col-lg-4 col-md-4 col-sm-4">
    @Html.LabelFor(model => model.EnterpriseId, "業務夥伴程式碼", htmlAttributes: new { @class = "control-label " })
    @Html.EditorFor(model => model.EnterpriseId, new { htmlAttributes = new { @class = "easyui-textbox1", data_options = "required:true ,validType:'length[0,20]'", tabindex = Num++, style = "width:100%" } })
    @Html.ValidationMessageFor(model => model.EnterpriseId, "", new { @class = "text-danger" })
</div>

Controller

public ActionResult GetIsUse(int Id,string EnterpriseId)
        {
            var IsUse = _cusBusInfoService.Queryable().Any(x => x.EnterpriseId == EnterpriseId && x.Id !=Id);
            return Json(!IsUse);

             //get需要增加JsonRequestBehavior.AllowGet，不然會報安全錯誤
        }

設定可以說是非常簡單，大部分工作都由微軟 幫我們做了，我們只需要關心業務邏輯