Error while Updating an existing entity.

I was following the tutorial http://docs.nopcommerce.com/pages/viewpage.action?pageId=1442499. I was able to change the data model successfully. But when I tried to change the presentation model I got following error. How can I fix it?

Server Error in '/' Application.

Validation type names in unobtrusive client validation rules must be unique. The following validation type was seen more than once: length

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: Validation type names in unobtrusive client validation rules must be unique. The following validation type was seen more than once: length

Source Error:


Line 414:                htmlAttributes = new { @class = "form-control" };
Line 415:
Line 416:            result.Append(helper.EditorFor(expression, new { htmlAttributes }));
Line 417:
Line 418:            return MvcHtmlString.Create(result.ToString());

Source File: c:\newfolder\nopCommerce\nopCommerce_3.80_Source\Presentation\Nop.Web.Framework\HtmlExtensions.cs    Line: 416

Stack Trace:


[InvalidOperationException: Validation type names in unobtrusive client validation rules must be unique. The following validation type was seen more than once: length]
   System.Web.Mvc.UnobtrusiveValidationAttributesGenerator.ValidateUnobtrusiveValidationRule(ModelClientValidationRule rule, IDictionary`2 resultsDictionary, String dictionaryKey) +910
   System.Web.Mvc.UnobtrusiveValidationAttributesGenerator.GetValidationAttributes(IEnumerable`1 clientRules, IDictionary`2 results) +135
   System.Web.Mvc.HtmlHelper.GetUnobtrusiveValidationAttributes(String name, ModelMetadata metadata) +265
   System.Web.Mvc.Html.InputExtensions.InputHelper(HtmlHelper htmlHelper, InputType inputType, ModelMetadata metadata, String name, Object value, Boolean useViewData, Boolean isChecked, Boolean setId, Boolean isExplicitValue, String format, IDictionary`2 htmlAttributes) +723
   System.Web.Mvc.Html.DefaultEditorTemplates.HtmlInputTemplateHelper(HtmlHelper html, String inputType, Object value) +68
   System.Web.Mvc.Html.DefaultEditorTemplates.HtmlInputTemplateHelper(HtmlHelper html, String inputType) +75
   System.Web.Mvc.Html.DefaultEditorTemplates.StringTemplate(HtmlHelper html) +7
   System.Web.Mvc.Html.ActionCacheCodeItem.Execute(HtmlHelper html, ViewDataDictionary viewData) +28
   System.Web.Mvc.Html.TemplateHelpers.ExecuteTemplate(HtmlHelper html, ViewDataDictionary viewData, String templateName, DataBoundControlMode mode, GetViewNamesDelegate getViewNames, GetDefaultActionsDelegate getDefaultActions) +321
   System.Web.Mvc.Html.TemplateHelpers.TemplateHelper(HtmlHelper html, ModelMetadata metadata, String htmlFieldName, String templateName, DataBoundControlMode mode, Object additionalViewData, ExecuteTemplateDelegate executeTemplate) +1072
   System.Web.Mvc.Html.TemplateHelpers.TemplateHelper(HtmlHelper html, ModelMetadata metadata, String htmlFieldName, String templateName, DataBoundControlMode mode, Object additionalViewData) +66
   System.Web.Mvc.Html.TemplateHelpers.TemplateFor(HtmlHelper`1 html, Expression`1 expression, String templateName, String htmlFieldName, DataBoundControlMode mode, Object additionalViewData, TemplateHelperDelegate templateHelper) +117
   System.Web.Mvc.Html.TemplateHelpers.TemplateFor(HtmlHelper`1 html, Expression`1 expression, String templateName, String htmlFieldName, DataBoundControlMode mode, Object additionalViewData) +104
   System.Web.Mvc.Html.EditorExtensions.EditorFor(HtmlHelper`1 html, Expression`1 expression, Object additionalViewData) +62
   Nop.Web.Framework.HtmlExtensions.NopEditorFor(HtmlHelper`1 helper, Expression`1 expression, Nullable`1 renderFormControlClass) in c:\newfolder\nopCommerce\nopCommerce_3.80_Source\Presentation\Nop.Web.Framework\HtmlExtensions.cs:416
   ASP._Page_Administration_Views_Category__CreateOrUpdate_cshtml.<TabInfo>b__0(TextWriter __razor_helper_writer) in c:\newfolder\nopCommerce\nopCommerce_3.80_Source\Presentation\Nop.Web\Administration\Views\Category\_CreateOrUpdate.cshtml:311
   System.Web.WebPages.HelperResult.ToString() +66
   System.Web.WebPages.HelperResult.ToHtmlString() +9
   Nop.Web.Framework.HtmlExtensions.RenderBootstrapTabContent(HtmlHelper helper, String currentTabName, HelperResult content, Boolean isDefaultTab, String tabNameToSelect) in c:\newfolder\nopCommerce\nopCommerce_3.80_Source\Presentation\Nop.Web.Framework\HtmlExtensions.cs:269
   ASP._Page_Administration_Views_Category__CreateOrUpdate_cshtml.Execute() in c:\newfolder\nopCommerce\nopCommerce_3.80_Source\Presentation\Nop.Web\Administration\Views\Category\_CreateOrUpdate.cshtml:21
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +197
   System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +105
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +90
   System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +235
   System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +107
   System.Web.Mvc.HtmlHelper.RenderPartialInternal(String partialViewName, ViewDataDictionary viewData, Object model, TextWriter writer, ViewEngineCollection viewEngineCollection) +277
   System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model, ViewDataDictionary viewData) +91
   System.Web.Mvc.Html.PartialExtensions.Partial(HtmlHelper htmlHelper, String partialViewName, Object model) +32
   ASP._Page_Administration_Views_Category_Edit_cshtml.Execute() in c:\newfolder\nopCommerce\nopCommerce_3.80_Source\Presentation\Nop.Web\Administration\Views\Category\Edit.cshtml:36
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy() +197
   System.Web.Mvc.WebViewPage.ExecutePageHierarchy() +105
   System.Web.WebPages.StartPage.RunPage() +17
   System.Web.WebPages.StartPage.ExecutePageHierarchy() +64
   System.Web.WebPages.WebPageBase.ExecutePageHierarchy(WebPageContext pageContext, TextWriter writer, WebPageRenderingBase startPage) +78
   System.Web.Mvc.RazorView.RenderView(ViewContext viewContext, TextWriter writer, Object instance) +235
   System.Web.Mvc.BuildManagerCompiledView.Render(ViewContext viewContext, TextWriter writer) +107
   System.Web.Mvc.ViewResultBase.ExecuteResult(ControllerContext context) +291
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult) +13
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +56
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilterRecursive(IList`1 filters, Int32 filterIndex, ResultExecutingContext preContext, ControllerContext controllerContext, ActionResult actionResult) +420
   System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult) +52
   System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +173
   System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +100
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
   System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +13
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36
   System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +12
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +22
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
   System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +21
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9765121
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +155

Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.6.1586.0

Please, show us your CategoryModel  

[Validator(typeof(CategoryValidator))]
    public partial class CategoryModel : BaseNopEntityModel, ILocalizedModel<CategoryLocalizedModel>
    {
        public CategoryModel()
        {
            if (PageSize < 1)
            {
                PageSize = 5;
            }
            Locales = new List<CategoryLocalizedModel>();
            AvailableCategoryTemplates = new List<SelectListItem>();
            AvailableCategories = new List<SelectListItem>();
            AvailableDiscounts = new List<SelectListItem>();
            SelectedDiscountIds = new List<int>();

            SelectedCustomerRoleIds = new List<int>();
            AvailableCustomerRoles = new List<SelectListItem>();

            SelectedStoreIds = new List<int>();
            AvailableStores = new List<SelectListItem>();
        }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.Name")]
        [AllowHtml]
        public string Name { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.Description")]
        [AllowHtml]
        public string Description { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.CategoryTemplate")]
        public int CategoryTemplateId { get; set; }
        public IList<SelectListItem> AvailableCategoryTemplates { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.MetaKeywords")]
        [AllowHtml]
        public string MetaKeywords { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.MetaDescription")]
        [AllowHtml]
        public string MetaDescription { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.MetaTitle")]
        [AllowHtml]
        public string MetaTitle { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.SeName")]
        [AllowHtml]
        public string SeName { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.Parent")]
        public int ParentCategoryId { get; set; }

        [UIHint("Picture")]
        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.Picture")]
        public int PictureId { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.PageSize")]
        public int PageSize { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.AllowCustomersToSelectPageSize")]
        public bool AllowCustomersToSelectPageSize { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.PageSizeOptions")]
        public string PageSizeOptions { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.PriceRanges")]
        [AllowHtml]
        public string PriceRanges { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.ShowOnHomePage")]
        public bool ShowOnHomePage { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.IncludeInTopMenu")]
        public bool IncludeInTopMenu { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.Published")]
        public bool Published { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.Deleted")]
        public bool Deleted { get; set; }

        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.DisplayOrder")]
        public int DisplayOrder { get; set; }
        
        public IList<CategoryLocalizedModel> Locales { get; set; }

        public string Breadcrumb { get; set; }

        //ACL (customer roles)
        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.AclCustomerRoles")]
        [UIHint("MultiSelect")]
        public IList<int> SelectedCustomerRoleIds { get; set; }
        public IList<SelectListItem> AvailableCustomerRoles { get; set; }
        
        //store mapping
        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.LimitedToStores")]
        [UIHint("MultiSelect")]
        public IList<int> SelectedStoreIds { get; set; }
        public IList<SelectListItem> AvailableStores { get; set; }


        public IList<SelectListItem> AvailableCategories { get; set; }


        //discounts
        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.Discounts")]
        [UIHint("MultiSelect")]
        public IList<int> SelectedDiscountIds { get; set; }
        public IList<SelectListItem> AvailableDiscounts { get; set; }

        
        [NopResourceDisplayName("Admin.Catalog.Categories.Fields.SomeNewProperty")]
        public string SomeNewProperty { get; set; }

        #region Nested classes

        public partial class CategoryProductModel : BaseNopEntityModel
        {
            public int CategoryId { get; set; }

            public int ProductId { get; set; }

            [NopResourceDisplayName("Admin.Catalog.Categories.Products.Fields.Product")]
            public string ProductName { get; set; }

            [NopResourceDisplayName("Admin.Catalog.Categories.Products.Fields.IsFeaturedProduct")]
            public bool IsFeaturedProduct { get; set; }

            [NopResourceDisplayName("Admin.Catalog.Categories.Products.Fields.DisplayOrder")]
            public int DisplayOrder { get; set; }
        }

        public partial class AddCategoryProductModel : BaseNopModel
        {
            public AddCategoryProductModel()
            {
                AvailableCategories = new List<SelectListItem>();
                AvailableManufacturers = new List<SelectListItem>();
                AvailableStores = new List<SelectListItem>();
                AvailableVendors = new List<SelectListItem>();
                AvailableProductTypes = new List<SelectListItem>();
            }

            [NopResourceDisplayName("Admin.Catalog.Products.List.SearchProductName")]
            [AllowHtml]
            public string SearchProductName { get; set; }
            [NopResourceDisplayName("Admin.Catalog.Products.List.SearchCategory")]
            public int SearchCategoryId { get; set; }
            [NopResourceDisplayName("Admin.Catalog.Products.List.SearchManufacturer")]
            public int SearchManufacturerId { get; set; }
            [NopResourceDisplayName("Admin.Catalog.Products.List.SearchStore")]
            public int SearchStoreId { get; set; }
            [NopResourceDisplayName("Admin.Catalog.Products.List.SearchVendor")]
            public int SearchVendorId { get; set; }
            [NopResourceDisplayName("Admin.Catalog.Products.List.SearchProductType")]
            public int SearchProductTypeId { get; set; }

            public IList<SelectListItem> AvailableCategories { get; set; }
            public IList<SelectListItem> AvailableManufacturers { get; set; }
            public IList<SelectListItem> AvailableStores { get; set; }
            public IList<SelectListItem> AvailableVendors { get; set; }
            public IList<SelectListItem> AvailableProductTypes { get; set; }

            public int CategoryId { get; set; }

            public int[] SelectedProductIds { get; set; }
        }

        #endregion      

    }

Validation type names in unobtrusive client validation rules must be unique. The following validation type was seen more than once: length

This error is because you were added validation more than once

Just change this line:

this.Property(m => m.SomeNewProperty).HasMaxLength(255).IsOptional();  

  

To:

this.Property(m => m.SomeNewProperty).IsOptional(); 

It worked. Thank you. Nop team may need to update documentation

You're welcome! Glad to know that🙂