Last Updated: 25 Mar 2021 12:04 by ADMIN
Created on: 11 Oct 2011 09:25
Category: Kendo UI for jQuery
Type: Feature Request
Validation is both a client-side and a server-side issue
Please think the Kendo UI validation farmework not only in terms of client-side validation but also in terms of reporting server-side errors.

A framework that would only provide a way to display a validation error message based on a client-side rule after each related input field would not be very helpful in my opinion.

All errors need to be reported in a consistent way. My preferred option is:
- a message box at the top of a form to display all messages including OK messages and error messages (client-side and server-side).
- higlighted fields with tooltips (not to clutter the form layout) to repeat error messages in context when applicable.

Although the framework built into Kendo UI might only provide client-side validation, please make sure to provide entry points into the UI used to report errors. Alternatively, leave the UI to the developer and provide a simple way to collect all validation error messages on a form.
Posted on: 26 Aug 2016 17:27
I'd like to comment on WHY server-side validation support is required for client-side library Kendo UI is (from Telerik point of view MVC extentions are just helpers for rendering client-side controls).

First of all, KendoUI doesn't live in vacuum. All data entered in your controls eventually will get to server. And it must be validated there. Consequently, there should be some mechanism of returning errors from server and displaying them on client UI. I'm not sure why it's not obvious for Telerik product designers/architects. 
So for some reason Telerik support client-side validation, but do not support server-side validation mechanism for their data-bound controls. There is just no protocol for returning an error. All you offer is ability to customly implement that logic.

Now, let's consider the scenario of migrating an application from native ASP.NET MVC to Kendo UI controls. If I understand correctly, you expect developers to use native server-validation mechanisms (e.g. Html.ValidationMessageFor(), Html.ValidationSummary() extension in MVC). But the problem is that it renders different layout than kendo client-side validation messages with no chance for sync and no suggested solution.

There are also problems, associated with kendo client templates, MVVM-bound views server-validation.

My main point is that kendo UI is NOT just a set of client controls. It introduces new concepts: client-side data-bound controls, client-side template for validation messages, client-side templates in general, MVVM, ... And those concepts have design flaws, particularly in validation area, which doesn't allow easy migration to kendo controls.

PS: It's already 5 years since "It will be conveyed to our devs to be taken into account".
Posted on: 31 Aug 2013 01:03
I'd like to comment that it is fine the way it is. In my configuration, server-side validation is handled by slick ASP.NET Web API ValidationAttributes. If the client receives 400 Bad Request from the API, it is caught and displayed via a global handler and notification control. That said, every configuration is different, and I am only using Kendo UI for client code (no server-side wrappers).
test test
Posted on: 28 Mar 2013 09:40
Also it's important that in case of the server errors  the popup editor to stay opened. 
The user must have the posibility to corect the error and then try again. 
The cancelChanges sample is strange because it rols back all the user's changes.
Sörnt Poppe
Posted on: 12 Mar 2013 17:39
Right know the validation "framework" is by far not ready for realworld applications.

a) No way to report server errors in a consistant way.

b) possitioning validation message within a grid pop up editor is only possible by hacking the "eventArgs.sender.editable.validatable._errorTemplate" while to grid goes into edit mode.

c) The error message constuctions is worst at least. You either need to localize each error message type or you will get "lovely" messages like "firstName is required" instead of "First name is required" because they use the "name" attribute - what a joke.

d) Validation rules defined at the DataSource are not evaluated within the pop up editor.

You really should fix the basic usage scenarios within your product.

But hey - Telerik loves to reinvent the wheel instead of providing integrating points for OSS like Knockout Validation.
Posted on: 21 Oct 2011 19:38
Great idea however I would like to chime in on it as well.

- Reporting server errors should be no different than reporting client errors as far as UI/user experience goes. Server errors should not look or behave any differently than client errors. We should be able to somehow map a collection of server errors to their corresponding input elements.

- Although the developer should have full control of the UI. There should be a well designed and through out default validation UI that should work for most scenarios. Not all developers like to spend extra time fine-tuning validation UI. It should just work.
Telerik Admin
Posted on: 11 Oct 2011 16:00
Thanks for the thorough feedback on validation. It will be conveyed to our devs  to be taken into account while developing the validation extensions for the framework.