DropDownBoxQueryDisplayTextContext Class

Stores information about editor value and text.

Namespace: DevExpress.Blazor

Assembly: DevExpress.Blazor.v24.1.dll

NuGet Package: DevExpress.Blazor

Declaration

public class DropDownBoxQueryDisplayTextContext

Remarks

The DxDropDownBox‘s input element is read-only for users. When you specify editor Value programmatically, implement the QueryDisplayText function to define how the editor value is displayed in the input element.

The function encapsulates an object of the DropDownBoxQueryDisplayTextContext type that contains the editor value (Value) and the previous input text (DisplayText).

Run Demo: DropDown Box - Multiple Selection ListBox

<label for="ddbMultipleSelectionListBox" class="demo-text cw-480 mb-1">Employees</label>
<DxDropDownBox @bind-Value="Value"
               QueryDisplayText="QueryText"
               DropDownWidthMode="DropDownWidthMode.EditorWidth"
               SizeMode="Params.SizeMode"
               InputId="ddbMultipleSelectionListBox"
               CssClass="cw-480"
               >
    <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"
                   >
        </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();
        Value = ListBoxData.Take(2);
    }
}

Inheritance

Object

DropDownBoxQueryDisplayTextContext