DxDropDownBox.DropDownHeaderTemplate Property

Specifies a template for the drop-down window’s header.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v24.1.dll

NuGet Package: DevExpress.Blazor

Declaration

[Parameter]
public RenderFragment<DropDownBoxTemplateContext> DropDownHeaderTemplate { get; set; }

Property Value

Type	Description
RenderFragment<DropDownBoxTemplateContext>	The header template.

Remarks

The drop-down window can include a header, body, and footer. Use the DropDownHeaderTemplate property to specify the content for the window’s header element.

DropDownHeaderTemplate has the context parameter. You can use the parameter’s DropDownBox property to get information about the processed editor.

Razor

@inject NwindDataService NwindDataService

<DxDropDownBox @bind-Value="Value"
                QueryDisplayText="QueryText"
                CssClass="ddBox">
    <DropDownHeaderTemplate>
        <span class="oi oi-person" />
        Select Employees:
    </DropDownHeaderTemplate>
    <DropDownBodyTemplate>
        <DxListBox @ref="listBox" 
                    Data="@ListBoxData" TData="Employee" TValue="Employee"
                    Values="@(GetListBoxValues(context.DropDownBox))"
                    TextFieldName="@nameof(Employee.Text)"
                    SelectionMode="ListBoxSelectionMode.Multiple"
                    ShowCheckboxes="true"
                    CssClass="templateListbox"/>
    </DropDownBodyTemplate>
    <DropDownFooterTemplate>
        <DxButton Text="OK" CssClass="btn-margin"
                  Click="@(() => SetDropDownBoxValue(context.DropDownBox))" />
        <DxButton Text="Cancel" RenderStyle="ButtonRenderStyle.Secondary"
                  Click="@(() => context.DropDownBox.HideDropDown())" />
    </DropDownFooterTemplate>
</DxDropDownBox>

@code {
    DxListBox<Employee, Employee> listBox;
    IEnumerable<Employee> ListBoxData { get; set; }
    object Value { get; set; }

    string QueryText(DropDownBoxQueryDisplayTextContext arg) {
        var names = (arg.Value as IEnumerable<Employee>)?.Select(x => x.LastName);
        return names != null ? string.Join(",", names) : string.Empty;
    }

    IEnumerable<Employee> GetListBoxValues(IDropDownBox dropDownBox) {
        return dropDownBox.Value as IEnumerable<Employee>;
    }

    void SetDropDownBoxValue(IDropDownBox dropDownBox) {
        dropDownBox.BeginUpdate();
        dropDownBox.Value = listBox.Values;
        dropDownBox.HideDropDown();
        dropDownBox.EndUpdate();
    }

    protected override async Task OnInitializedAsync() {
        ListBoxData = await NwindDataService.GetEmployeesAsync();
        Value = ListBoxData.Take(2);
    }
}

CSS

.templateListbox {
    --dxbl-list-box-border-width: 0px;
    width: 100%
}
.ddBox {
    max-width: 480px;
    width: 100%;
}
.btn-margin {
    margin-right: 8px;
}

Implements

DropDownHeaderTemplate