How do I had a "Select All" option to a RadMultiSelect? I've see a couple of pages showing is but I can't find it in the docs or examples.

Thanks for any help.

look at you site it doesnt work on here either

https://demos.telerik.com/aspnet-ajax/multiselect/serversideevents/defaultcs.aspx

Recently I've been expressing some weird behavior with the MultiSelect displaying and extra dropdown next to the control (see attached image).  This is just standard markup, nothing fancy. Is there a property setting I'm missing? 

Thanks for any help you can provide.

<telerik:RadMultiSelect ID="msLOB" runat="server" Width="100%" Filter="StartsWith" Placeholder="Select LOB" DataTextField="text" DataValueField="value" Skin="Silk" RenderMode="Lightweight">
    <Items>
       <telerik:MultiSelectItem Text="All" Value="All" Selected="false"></telerik:MultiSelectItem>
       <telerik:MultiSelectItem Text="Commercial-Large" Value="Commercial-Large" Selected="false"</telerik:MultiSelectItem>
       <telerik:MultiSelectItem Text="Commercial-Small" Value="Commercial-Small" Selected="false"></telerik:MultiSelectItem> 
        <telerik:MultiSelectItem Text="Commercial-Individual" Value="Commercial-Individual" Selected="false"> 
        </telerik:MultiSelectItem>
       <telerik:MultiSelectItem Text="Medicare-MAPD" Value="Medicare-MAPD" Selected="false"></telerik:MultiSelectItem>
  </Items>
</telerik:RadMultiSelect>

Hi all,

I'm basically trying to create something similar to the demo presented here:

https://demos.telerik.com/aspnet-ajax/multiselect/virtualization/defaultcs.aspx

I've got a web service as a data source, and everything works (and looks) great without virtualization. I would obviously like to reap the benefits of virtualization, since the multiselect could potentially need to pull in a lot of data.

The issue occurs when I'm trying to select an item:

Telerik.Web.UI.WebRe…1f%3a619d6d01:13732 Uncaught TypeError: Cannot read properties of null (reading 'toJSON')
    at init.select (Telerik.Web.UI.WebRe…3a619d6d01:13732:38)
    at init.trigger (Telerik.Web.UI.WebRe…%3a619d6d01:5322:14)
    at init._select (Telerik.Web.UI.WebRe…%3a619d6d01:13489:7)
    at init._click (Telerik.Web.UI.WebRe…%3a619d6d01:13247:3)
    at init.d (Telerik.Web.UI.WebRe…a619d6d01:2435:3873)
    at init.trigger (Telerik.Web.UI.WebRe…%3a619d6d01:5322:14)
    at init._clickHandler (Telerik.Web.UI.WebRe…3a619d6d01:12931:54)
    at HTMLLIElement.d (Telerik.Web.UI.WebRe…a619d6d01:2435:3873)
    at HTMLUListElement.dispatch (Telerik.Web.UI.WebRe…619d6d01:2436:12445)
    at r.handle (Telerik.Web.UI.WebRe…a619d6d01:2436:9174)

Also, if I try to hook onto the OnSelect client-side event, it seems that the data item is not populated - my function onSelect(sender, args) gets triggered, but args.get_dataItem() returns null. Is it possible some binding didn't go as planned? Is there an extra step that needs to be done when using virtualization, or does perhaps some additional data need to be returned from the web service?

My VirtualSettings look like this:

<VirtualSettings ItemHeight="25" MapValueTo="dataItem" ValueMapper="valueMapper" />

and the ValueMapper isn't to blame because it's not getting triggered; I'm doing a simple scenario where there are no initially selected values to display.

I've tried going through docs for both RadMultiSelect and the Kendo control it wraps, but to no avail. I was initially using a version released in 2022, but have tried just replacing it with 2023.3.1010 - it didn't seem to help. I've also tried explicitly adding the  Virtual="true" option to my RadMultiSelect instance, but that seemed to have no effect either.

Hi Team,
I tried following steps to use RadMultiSelect dropdown in my project but getting compile time error . 
1) I have registered Telerik.Web.UI assembly in aspx page
2) Added RadScriptManager and RadSkinManager on aspx page.
3) then added following code - 
<telerik:RadMultiSelect runat="server" DataValueField="text" Filter="Contains" EnforceMinLength="false" Placeholder="Select Receiptees"
    DataTextField="text" Width="500px" ID="requiredMultiSelect">
<Items>
<telerik:MultiSelectItem Text="Steven White"></telerik:MultiSelectItem>
<telerik:MultiSelectItem Text="Nancy King"></telerik:MultiSelectItem>
</Items>
</telerik:RadMultiSelect>   
4) added this line in aspx.vb file for default selection
requiredMultiSelect.Value = {"Anne King", "Andrew Fuller"}

And getting compile time error -
Type 'Global.Telerik.Web.UI.RadMultiSelect' is not defined.

Not able to find solution for this on telerik webpage also , Can anyone please help me with this?

The RadMultiSelect implementation has one error that WCAG 4.1.1 parsing is catching. There is a duplicate span with the same id.

Found in the page source of the demo page (similar to how I implemented as well):

https://demos.telerik.com/aspnet-ajax/multiselect/virtualization/defaultcs.aspx

<select name="ctl00$ContentPlaceholder1$RadMultiSelect1" multiple="" id="ctl00_ContentPlaceholder1_RadMultiSelect1" class="RadMultiSelect RadMultiSelect_Silk" style="width:400px;">
<span id="ctl00_ContentPlaceholder1_RadMultiSelect1_WebServiceCDS" style="display:none;"></span><input id="ctl00_ContentPlaceholder1_RadMultiSelect1_ClientState" name="ctl00_ContentPlaceholder1_RadMultiSelect1_ClientState" type="hidden" />
</select><span id='ctl00_ContentPlaceholder1_RadMultiSelect1_WebServiceCDS' style='display:none'></span>

Hi Telerik team,

the "Contrast Security" tool we use shows us a "Untrusted Deserialization" Vulnerability found on one of the ASPX (webForms) page where we utilize RadMultiSelect control. (Our current version is 2021.1.119.45). 

Could you please suggest any options now to fix it, please?  

Details:

Tracked the following data from "ctl00_Main_content_ddlMSelectMultipleStaff_ClientState...:

POST /vosnet/communications/scheduler/default.aspx

ctl00_Main_content_ddlMSelectMultipleStaff_ClientState={"enabled":true,"selectedItems":[],"deselectedItems":[],"value":[2613],"selectedDataItems":[{"text":"Skaggs","value":"2613","Lastname":"Skaggs","Userid":2613,"attributes":{"FullName":"Skaggs Kari","Color":"background-color:rgb(89,20,195);","ColorARGB":"5838019"}}]}&ctl00$textsize=.......SNIP...........

...which was accessed within the following code:
Telerik.Web.UI.RadMultiSelect.LoadPostData()

...and ended up being deserialized with code that looks like this:
m = serializer.Deserialize<M>("{"enabled":true,"selectedItems":[],"deselectedI...")

I'm using a Rad MultiSelect to search for people, and I would like to include a link to the selected person's profile page within the item template.  I noticed that when I use a RadButton, I don't see it on the page.  When I use the <a OnClick> I see the hyperlink but I can't hit the controller action.  

Is it possible that I just can't use a RadButton in the MultiSelect Item Template?

<ItemTemplate>
                      <span class="k-state-default">
                         <p>#: data.Foo#</p>
													
			<a OnClick="detailsViewClick" runat="server" ID="Bar">View Details</a>

                         <%--    Commented out because this does not even show up on the view 
 <telerik:RadButton RenderMode="Lightweight" ID="Bar" runat="server" Text="ViewDetails"  OnClick="detailsViewClick" >
                        </telerik:RadButton>--%>

                         </span>
</ItemTemplate>

I am getting the following error when using RadMultiSelect with over 13000 records:

Error InnerException Message: Error during serialization or deserialization using the JSON JavaScriptSerializer. The length of the string exceeds the value set on the maxJsonLength property.
 Error InnerException StackTrace:    at System.Web.Script.Serialization.JavaScriptSerializer.Serialize(Object obj, StringBuilder output, SerializationFormat serializationFormat)
   at Telerik.Web.UI.AdvancedJavaScriptSerializer.Serialize(Object obj)
   at Telerik.Web.UI.RadMultiSelect.DescribeItems(IScriptDescriptor descriptor)
   at Telerik.Web.UI.RadMultiSelect.DescribeComponent(IScriptDescriptor descriptor)
   at Telerik.Web.UI.ScriptRegistrar.GetScriptDescriptors(Control control)
   at Telerik.Web.UI.RadDataBoundControl.GetScriptDescriptors()
   at System.Web.UI.ScriptControlManager.RegisterScriptDescriptors(IScriptControl scriptControl)
   at Telerik.Web.UI.RadDataBoundControl.RegisterScriptDescriptors()
   at Telerik.Web.UI.RadDataBoundControl.Render(HtmlTextWriter writer)
   at Telerik.Web.UI.RadMultiSelect.Render(HtmlTextWriter writer)
   at System.Web.UI.Control.RenderControlInternal(HtmlTextWriter writer, ControlAdapter adapter)

I already have <jsonSerialization maxJsonLength="2147483647"> in my web.config but still errors out.

Telerik.Web.UI Version: 2022.2.622.45

Seems similar to this issue: https://www.telerik.com/forums/maxjsonlength-exceeded-in-radmap

But updating to higher version than 2020 didn't seem to solve it. Was the fix only for RadMap?

I'm trying to add ToolTip content dynamically with items selected/unselected from the Multiselect control.  The code seems to work with no errors. However, the tooltip doesn't show on mouse over the Multiselect control. 

I also attempted to add an mouseover client attribute event on the Multiselect as well.

Code snippets attached. 

Thank you for any help with this issue!