Hi,
We are using the DropDownList component as an inline editor in the grid, for managing a product hierarchy. Previously we were using the DropDownList with grouping enabled, without virtualization, but due to volume of data we now need to use virtualization.
This does not work with grouping at the moment.
At the bottom of this page it is mentioned that 'Virtual scrolling with grouping will be supported in a future version.'.
Any timeline on this feature?
KR,
Lennert
When the Default text value is changed by some business logic, the component does not react to that change to update the Default text value in the view model.
DropDownList should re-render on change of the Default text parameter
Clicking on the <label> opens the dropdown, but clicking on its main element does not
Selected value: @selectedValue
<br />
<label>some label for the dropdown, open it and test whether clicking outside closes it
<TelerikDropDownList Data="@myDdlData" TextField="MyTextField" ValueField="MyValueField" @bind-Value="selectedValue">
</TelerikDropDownList>
</label>
@code {
//in a real case, the model is usually in a separate file
//the model type and value field type must be provided to the dropdpownlist
public class MyDdlModel
{
public int MyValueField { get; set; }
public string MyTextField { get; set; }
}
IEnumerable<MyDdlModel> myDdlData = Enumerable.Range(1, 20).Select(x => new MyDdlModel { MyTextField = "item " + x, MyValueField = x });
int selectedValue { get; set; } = 3; //usually the current value should come from the model data
}
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.
Hello,
If I scroll the page down and open a filterable DropDownList, the page will scroll up.
Here is a REPL test page
UI for Blazor 2.30 works as expected. This broke in version 3.0.0. The issue exists only in WebAssembly apps.
The drop down list component does not allow the user to associate a label with the underlying html select input control, which goes against accessibility standards. It appears that most, if not all, of the other components follow the accessibility standards. Please fix the drop down list and/or allow attribute splatting so that developers can apply their own attributes (like aria-label) to meet accessibility standards.
I have two cascaded dropdownlists, in attached example car brands and selectable colors. The dependent dropdown has defaulttext option. After the parent dropdown has changed, in its event handler I reload the dependent data source and set a new valid value. If the data source does not contain the previous (!) value, the dropdownlist calls the valuechanged callback with default value. In next round when dependent dropdown holds the default value, after reloading datasource it works as expected. And parent changes again, if the updated datasource does not contain the previous dependent value the dropdownlist sets its value to default.
When I do not pass defaulttext parameter, the dependent dropdown selects the first element from the updated datasource. In my case it is not acceptable because I want to set a specific value (in this example the default color), not the first and not the default.
This feedback drives me to try setting value to default and wait for re-render the descendant dropdownlist before set the wanted value.
Is there any way to avoid this behaviour of the dropdownlist?
<TelerikDropDownList TItem="Brand"
TValue="int"
ValueField=@nameof(Brand.Id)
TextField=@nameof(Brand.Name)
Data="@BrandList"
Value="@Data.BrandId"
ValueChanged=@OnBrandChanged />
<TelerikDropDownList TItem="Color"
TValue="int"
ValueField=@nameof(Brand.Id)
TextField=@nameof(Brand.Name)
Data="@FilteredColorList"
Value="@Data.ColorId"
ValueChanged="@OnColorChanged"
DefaultText="select color ..." />
async Task OnBrandChanged(int brandId)
{
Data.ColorId = default;
await Task.Delay(5);
Data.BrandId = brandId;
Data.ColorId = GetDefaultColor(brandId);
FilteredColorList = GetFilteredColorList(brandId);
}
The DropDownList remains open after tabbing and does not fire. It also won't fire OnBlur and OnChange in this case. The problem occurs only if the component was opened by clicking exactly on its arrow.
Here is a test page: https://blazorrepl.telerik.com/cxEfFVPq042owTt616
The workaround is to wrap the component in a <span> that handles @onfocusout and closes the component programmatically: https://blazorrepl.telerik.com/cnafPCYL21aT3fpD05
Hi!
When i use combination of LINQ inside TelerikDropDownLists Data attribute and TelerikGrid 's GridEditMode.Popup mode, i get weird behavior when i try to select an item from TelerikDropDownLists - everything freezes. Please check the solution. Everything works fine if i don't use LINQ or GridEditMode.Popup mode.
Thank you!
Hello,
Initial I want no item to be selected to let the user select a value. I thought it would be enough if my bindvalue would be of a nullable type. I'm getting an exception when trying. If this is not supported, how can I do it?
<div class="form-group col-md-2">
<label class="col-form-label" for="ddReleaseType">Fönstertyp</label>
<TelerikDropDownList Data="@ReleaseTypeFilterOptions" @bind-Value="FilterState.ReleaseType" TextField="DisplayText" ValueField="ReleaseType" Class="max-width form-control" @ref="ddReleaseType"></TelerikDropDownList>
</div>
public enum ReleaseType : int
{
All = 0,
Category = 1,
Season = 2,
Misc = 3
}
protected Telerik.Blazor.Components.TelerikDropDownList<ReleaseTypeFilterModel?, SessionState.ReleaseType?> ddReleaseType;
protected class ReleaseTypeFilterModel
{
public SessionState.ReleaseType ReleaseType { get; set; }
public string DisplayText { get { return ReleaseType.ToString(); } }
}
Telerik.Blazor.Components.Common.TelerikSelectBase<TItem, TValue>.TryParseValueFromString(string value, out TValue result, out string validationErrorMessage)
_Host.cshtml
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).
When bound to a nullable GUID, the DropDownList invokes validation and shows validation messages as soon as the view loads.
Expected: the same behavior as with nullable int - validation is to be triggered by the form submission or selection from the dropdown.
Worked as expected in 1.2.0.
Reproducible:
@
using
Telerik.Blazor.Components.DropDownList
@
using
System.ComponentModel.DataAnnotations
<EditForm Model=
"@person"
OnValidSubmit=
"@HandleValidSubmit"
>
<DataAnnotationsValidator />
<ValidationSummary />
<p
class
=
"gender"
>
Gender: <TelerikDropDownList @bind-Value=
"person.Gender"
DefaultItem=
"@ddlHint"
Data=
"@genders"
TextField=
"MyTextField"
ValueField=
"MyValueField"
>
</TelerikDropDownList>
<ValidationMessage For=
"@(() => person.Gender)"
></ValidationMessage>
</p>
<button type=
"submit"
>Submit</button>
</EditForm>
@code {
// Usually the model classes would be in different files
public
class
Person
{
[Required(ErrorMessage =
"Gender is mandatory."
)]
//the value field in the dropdown model must be null in the default item
public
Guid? Gender {
get
;
set
; }
}
public
class
MyDdlModel
{
//nullable so the default item can allow required field validation
public
Guid? MyValueField {
get
;
set
; }
public
string
MyTextField {
get
;
set
; }
}
Person person =
new
Person();
MyDdlModel ddlHint =
new
MyDdlModel { MyValueField =
null
, MyTextField =
"Gender"
};
IEnumerable<MyDdlModel> genders =
new
List<MyDdlModel>
{
new
MyDdlModel {MyTextField =
"female"
, MyValueField =
new
Guid()},
new
MyDdlModel {MyTextField =
"male"
, MyValueField =
new
Guid()},
new
MyDdlModel {MyTextField =
"other"
, MyValueField =
new
Guid()},
new
MyDdlModel {MyTextField =
"I'd rather not say"
, MyValueField =
new
Guid()}
};
void
HandleValidSubmit()
{
Console.WriteLine(
"OnValidSubmit"
);
}
}
Using DropDownList with Filter enabled will lost track of Focus when an item from dropdown is selected or tabbing away from filter input.
Steps to reproduce:
Expected Behavior:
Focus in the next focusable element
Actual Behavior:
Focus is lost, and will go to the browser buttons
It is possible to reproduce in the demos:
https://demos.telerik.com/blazor-ui/dropdownlist/filtering