Hello everyone,
We have opened this Feature Request to gather your insights on the addition of disabled items for the DropDownList.
For the time being, you can make items look disabled via DropDownListItemTemplate. Also, prevent clicks with @onclick and use the ValueChanged event to skip disabled items during keyboard navigation.
UPDATE: The associated built-in feature is the OnItemRender event, which can help style specific items without a template.
<TelerikDropDownList Data="@Products"
TItem="@Product"
TValue="@(int?)"
Value="@SelectedProductId"
ValueField="@nameof(Product.Id)"
TextField="@nameof(Product.Name)"
DefaultText="Select Product..."
ValueChanged="@( (int? newValue) => SelectedProductChanged(newValue) )"
Width="200px">
<DropDownListSettings>
<DropDownListPopupSettings Class="disabled-items" />
</DropDownListSettings>
<ItemTemplate>
@{ var p = context as Product; }
<div class="item-div @( !p.Active ? "disabled" : "" )"
@onclick:preventDefault="@(!p.Active)"
@onclick:stopPropagation="@(!p.Active)">
@p.Name
</div>
</ItemTemplate>
</TelerikDropDownList>
<style>
/* remove default item padding to prevent selection outside the template div */
.disabled-items .k-list-item {
padding: 0;
}
/* add back inner padding */
.disabled-items .item-div {
padding: 4px 8px;
}
/* style disabled items */
.disabled-items .disabled {
cursor: not-allowed;
width: 100%;
color: #ccc;
}
</style>
@code {
private List<Product> Products { get; set; }
private int? SelectedProductId { get; set; }
private async Task SelectedProductChanged(int? newValue)
{
var newProduct = Products.FirstOrDefault(x => x.Id == newValue);
if (newProduct?.Active == true || !newValue.HasValue)
{
// select only active items or DefaultText
SelectedProductId = newValue;
}
else
{
// skip disabled items during keyboard navigation
var oldProductIndex = Products.FindIndex(x => x.Id == SelectedProductId);
var newProductIndex = Products.FindIndex(x => x.Id == newValue);
if (newProductIndex > oldProductIndex)
{
// skip forward
SelectedProductId = Products[++newProductIndex].Id;
}
else
{
// skip backward
SelectedProductId = Products[--newProductIndex].Id;
}
}
}
protected override void OnInitialized()
{
Products = new List<Product>();
for (int i = 1; i <= 7; i++)
{
var active = i % 3 != 0;
Products.Add(new Product()
{
Id = i,
Name = (active ? "" : "Disabled ") + "Product " + i,
Active = active
});
}
base.OnInitialized();
}
public class Product
{
public int Id { get; set; }
public string Name { get; set; }
public bool Active { get; set; }
}
}
Hi,
Is it possible to implement search/look-ahead in the current version of the DropDown component? If not, will you be adding this feature soon?
Thank you.
Ben
Right now when a DropDownList has PopupHeight="Auto" the popup gets the height necesaary to display its items properly.
But when there are many items the popup also displays all items without a vertical scrollbar (maybe over the entire page and beyond), which is not good.
My suggestion would be to add a property for specifyig a "MaxPopupHeight" to limit the growth of the popup.
Also if "PopupHeight" is not specified it should take "Auto" as the default value instead of a static height in px, instead give the new "MaxPopupHeight" a limiting default value.
***Admin Edit***
Released in 3.0.0 through PopupSettings tag: https://docs.telerik.com/blazor-ui/upgrade/breaking-changes/3-0-0#popup-settings
***Admin Edit***
Is it possible to drop dropDownList from outside, for example after its data has been changed, without clicking on it ?
ADMIN EDIT:
This feature is also applicable to ComboBox, AutoComplete, Multiselect, Date and Time Pickers components.
Posting this feature request as per your suggestion in my original forum post at: https://www.telerik.com/forums/data-source-using-scalar-list
I would like the DropDownList component to support lists of scalar values as data source. I.e:
<TelerikDropDownList Data="@MyList" bind-Value=@MyItem>
</TelerikDropDownList>
@functions {
protected List<string> MyList = new List<string>() { "a", "b", "c" };
protected string MyItem { get; set; } = "b";
}
The DropDownList would infer the scalar type from the Data property. The TextField items shown in the list (and the associated ValueField) would be the same: i.e. the value of each scalar in the list.
As stated in the documentation the Event OnChange for DropDownList is shown by intellisense but should not be used. However, in some situations it would be very useful to bind the value of the DropDownList and additionally have an event when the value changes, e.g. show additional inputs when a value is selected.
Currently it is either possible to have data binding to value by @bind-Value or listen for the changed event by using Value and ValueChanged.
Add the ability to make the drop down list expanded contents wider than the closed control, or just automatically determine appropriate width (doesn't always work well for very long text fields, so you need both properties).