DxDropDown.Showing Event
Fires before the drop-down window is displayed.
Namespace: DevExpress.Blazor
Assembly: DevExpress.Blazor.v24.2.dll
NuGet Package: DevExpress.Blazor
Declaration
[Parameter]
public EventCallback<DropDownShowingEventArgs> Showing { get; set; }
Event Data
The Showing event's data class is DropDownShowingEventArgs. The following properties provide information specific to this event:
Property | Description |
---|---|
Cancel | Gets or sets a value indicating whether the event should be canceled. Inherited from CancelEventArgs. |
CancellationToken | Specifies an object that propagates a cancellation notification. |
Remarks
The Showing
event fires before the drop-down window is displayed and allows you to cancel the action. This event occurs in the following cases:
Set the event argument’s Cancel property to true
to cancel the action.
You can handle the Shown event that fires after the drop-down window is displayed. To process close actions, handle the Closing and Closed events.
The following example allows users to display the drop-down window only after they enable the checkbox:
<div>
<DxCheckBox @bind-Checked="@Checked">Allow Drop-Down Window</DxCheckBox>
<DxButton Id="button" RenderStyle="ButtonRenderStyle.Primary" Text="Show" Click="() => IsOpen = true" />
</div>
<DxDropDown @bind-IsOpen="@IsOpen"
HeaderText="Header"
BodyText="Lorem ipsum dolor sit amet, consectetur adipiscing elit. Mauris sit amet metus vel
nisi blandit tincidunt vel efficitur purus."
Width="400"
PositionTarget="#button"
PositionMode="DropDownPositionMode.Bottom"
Showing="WindowShowing"
Shown="WindowShown">
</DxDropDown>
@code {
bool Checked { get; set; }
bool IsOpen { get; set; }
void WindowShowing(DropDownShowingEventArgs args) {
args.Cancel = !Checked;
}
void WindowShown(DropDownShownEventArgs args) {
Checked = false;
}
}