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V25.1
  • DxDropDownBox.NullText Property

    Specifies the prompt text displayed in the editor when its value is null.

    Namespace: DevExpress.Blazor

    Assembly: DevExpress.Blazor.v25.1.dll

    NuGet Package: DevExpress.Blazor

    Declaration

    [DefaultValue(null)]
    [Parameter]
    public string NullText { get; set; }

    Property Value

    Type Default Description
    String null

    The prompt text.

    Remarks

    The DxDropDownBox‘s input element is read-only for users. Use the Value property to assign an editor value programmatically and implement the QueryDisplayText function to define how the editor value is displayed in the input element.

    Use the NullText property to display prompt text in the editor when Value is null.

    Run Demo: DropDown Box - Multiple Selection ListBox

    <DxDropDownBox @bind-Value="Value" 
                   QueryDisplayText="QueryText" 
                   NullText="Select values" 
                   ClearButtonDisplayMode="DataEditorClearButtonDisplayMode.Auto">
        <DropDownBodyTemplate>
            <DxListBox Data="@ListBoxData" TData="Employee" TValue="Employee"
                        Values="@(GetListBoxValues(context.DropDownBox))"
                        ValuesChanged="@(values => ListBoxValuesChanged(values, context.DropDownBox))"
                        TextFieldName="@nameof(Employee.Text)"
                        SelectionMode="ListBoxSelectionMode.Multiple"
                        ShowCheckboxes="true"
                        CssClass="templateListbox"
                        SizeMode="Params.SizeMode">
            </DxListBox>
        </DropDownBodyTemplate>
    </DxDropDownBox>
    
    @code {
        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 ListBoxValuesChanged(IEnumerable<Employee> values, IDropDownBox dropDownBox) {
            dropDownBox.BeginUpdate();
            dropDownBox.Value = values;
            dropDownBox.EndUpdate();
        }
    
        protected override async Task OnInitializedAsync() {
            ListBoxData = await NwindDataService.GetEmployeesAsync();
        }
    }
    

    DropDownBox with null text

    Implements

    See Also