I have created a new Telerk UI for ASP.NET Core R2 2018 SP1 Project and added a DropDownList Component into page.
When I use "Items" to add items manually everything is OK. but when I try to use DataSource to add Items using an Action remotely a console error is happened as "Uncaught TypeError: Cannot read property 'slice' of undefined".
JSON items is received and nothing is shown because of that error.
Please HELP

Currently the data-* attributes on the <option> tags are removed by the kendoDropDownList widget.
Please pass them through so they can be used.

After searching the kendo.all.js I found that there is currently no way the custom data-* can be added into the generated html code.

I'm using MVVM for a rather large SPA. Some parts of the SPA is generated on the server (webservice) which is just a partial html. Which looks like (simplest one):
<select data-role="dropdownlist" name="ProductTypeID" class="k-textbox">
	<option value="9" data-cond="DependsValue(ProductTypeCategoryID,1)">Compliments cards</option>
	<option value="1" data-cond="DependsValue(ProductTypeCategoryID,1)">Flyers</option>
	<option value="3" data-cond="DependsValue(ProductTypeCategoryID,3)">Brochures</option>
	<option value="25" data-cond="DependsValue(ProductTypeCategoryID,6)">Roll-up banners</option>
</select>

In this case the data-cond is an attribute in which there is a (javascript) function that should be run to determine if this option is valid or not (it is made hidden if not).

I was trying to convert this into a datasource which can be bound to the dropdownlist, but this has several drawbacks. The most important are:

- There are almost 60 different of these kind of dropdowns that can be generated from the server; This means a lot of extra code and webservices.

- Calling the webservice for each of them is way to slow since each field changes conditional values of other fields, and so the server would be called way to often. But on the client side this runs way faster. Even in javascript.

- The data-* attributes should be supported accordingly the html5 standard to my humble opinion :)

I found two questions regarding this, but both where unanswered.

I add them here for you comfort :)

http://www.telerik.com/forums/converting-standard-select-element-to-kendodropdownlist-removes-additional-properties-from-option-such-as-data-

http://www.telerik.com/forums/how-to-access-data--attributes-in-a-option-after-converting-select-to-a-dropdownlist

Hi guys! I am glad to be back with another feature suggestions for future Kendo UI releases. I am currently working on a project for a client using Kendo UI Multiselect control. The client's pizza ordering system has an interesting feature for selecting double or single portion ingredients. Currently, I'm only able to display the selected items individually, so what it means is that in the selected items, you see 2 of those same items. Perhaps in the future release, can you have some sort of checking to see if there is double entries, and group those into something like "Cheese (x2)". Honestly, this will make Multiselect so much more cooler!! And when the user decides to click on the "X" beside the item with double items, it simply removes one of the selected items by removing the ",id", and then removes the (x2) text. And ofcourse, for better user experience, Kendo UI Multiselect should automatically calculate the number of a single id has been added everytime the user selects the same item.

When the user enters a filter, the list is filtered. But if the user deletes the filter by clicking on the X in the filter box, the list remains filtered. It does not revert to the full, unfiltered list. 

To get back to the full list, the user must delete the filter by backspacing or pressing the delete key on the keyboard.

This behavior is confusing some users, who have used the mouse to delete the filter in IE11.  There's no longer a filter string there, but the list is still filtered.

Can  the dropdownlist listen for the click that clears the filter string from the textbox?

Create the ability to customize tag templates on the combobox and autocomplete widgets just like the tag template functionality on the multiselect widget

The default behaviour of select elements is to open up with a space-keypress when the elemented is selected (focused). 

The keyboard navigation in drop down lists is currently inconsistent based on the widget configuration.  When not filterable, the drop down allows you to type the first letter of one of the options in order to select it when the drop down is closed.  For example, tab to the drop down, do not open it, and type 'b' to select Bob. 

When the drop down is filterable, that behavior does not work.  You must use alt-down to expand the drop down and then begin filtering.  

I propose that the widget can consistently handle both cases by detecting whether the drop down is currently open in the keydown handler.  If filterable, and open, move into the filtering logic.  If filterable, and closed, stick with the standard selection logic.

ComboBox and DropDown are different because the first allows you to enter values non in list, but if you are using Cascading ComboBox, entering a value non in list in the first choice, the second choice is disabled. I'like to have cascading for values in list with option for inserting values non in list.

the multiselect control should have the possibility to define elements as not editable (readonly) so that those elements can not be removed while other elements can be removed or new elements can be added.

Please consider adding pagination to the multi-select dropdown and also the select all, deselect all options to appear inside the dropdown instead of below the input field.

It would be awesome to have the DropDownList automatically open upon focus and if filtering is enabled the focus/select the filter textbox.

This is great from a data entry standpoint where keyboard Navigation like Tab keys are used.

Maybe a property lag like OpenOnFocus=true

Currently to close the colorPicker manually, we have to do ".kendoColorPicker('close')", however the rest of the dropdowns/combos uses ".kendoPopup('close')".

It will be great to support it as well with colorPickers to allow closing of all popup elements on scroll with a uniform solution

When there is no filter enabled in the DropDownList it is possible to select an item just by typing, without opening the DropDownList popup.

https://dojo.telerik.com/ELEfIZIx

It would be useful if such an option is available when the filter of the widget is configured. 

If you're trying to create an accessible form, "the value of the for attribute must be the same as the value of the id attribute of the form control" [1]. Since the ComboBox widget generates a new element and hides the original select element, the for attribute no longer matches this new input element. I think it would be good if the ComboBox widget would somehow keep the for attribute of the associated label element in sync with the newly generated input element.

[1]: http://www.w3.org/TR/2012/NOTE-WCAG20-TECHS-20120103/H44

Hi Team,

I'd like to request the functionality to add a Clear Button  for the Kendo UI DropDownList similar to the ComboBox.  

Thank you!

Hi Team, 

I would like to request to add a class which associates with the Kendo DropDownList.  This way, the developer could use CSS instead of jQuery to change the style of the specific popup.  

Thank you!

Users wonder why the filter has not been removed from the dropdownlist when they use a browser's text INPUT[X] to delete the filter. The browser raises no event is raised when the X is clicked, and so the list does not revert to the unfiltered list. Users must hit the Delete keys on the keyboard. Although developers can use CSS to remove the browser's [X], it would be more convenient if kendo could do this by default for the dropdownlists's filter box, so that developers would not have to remember to add the CSS every time.

Currently it is not possible to show the filter row until some data has been received and the dropdown is visible.

Please enhance/change the DropDownList widget so that it will be possible the enter a filter expression before any data is queried.

Related forum post: http://www.telerik.com/forums/server-filtering-how-to-not-query-data-until-filter-has-been-provided

Now autocomplete can not use to suggest email input, just like I input my name, the widget can show myname@xxx1.com, myname@xxx2.com, myname@xxx3.com like this, and the data will be only [{"email":"@xxx1.com"},{"email":"@xxx2.com"},{ "email":"@xxx3.com"}]

Not showing the selected items externally , only within the drop down.