How to apply search and filter for one column in WPF DataGrid (SfDataGrid)?

<Grid>
    <Grid.RowDefinitions>
 
        <RowDefinition Height="50"/>
        <RowDefinition Height="*"/>
    </Grid.RowDefinitions>
    <WrapPanel Grid.Row="0">
        <StackPanel Width="50" />
        <TextBox x:Name="TextBox" Height="30" Width="100" />
        <StackPanel Width="10" />
    </WrapPanel>
 
    <syncfusion:SfDataGrid x:Name="dataGrid" Grid.Row="1"
                            AutoGenerateColumns="True" 
                            AllowFiltering="True" 
                            AllowResizingColumns="True" 
                            EnableDataVirtualization="True"
                            ShowBusyIndicator="True"
                            AllowEditing="True"              
                            ItemsSource="{Binding Path=ItemSource}"/>
</Grid>

public class SearchHelperExt : SearchHelper
{
    public SearchHelperExt(SfDataGrid datagrid) : base(datagrid)
    {
    }
        
    protected override bool SearchCell(DataColumnBase column, object record, bool ApplySearchHighlightBrush)
    {
        if (column == null)
            return false;
        if (column.GridColumn.MappingName == "EmployeeId")
        {
            return base.SearchCell(column, record, ApplySearchHighlightBrush);
        }
        else
            return false;
    }
 
    protected override bool FilterRecords(object dataRow)
    {
        if (string.IsNullOrEmpty(SearchText))
            return true;           
 
        if (this.Provider == null)
            Provider = this.DataGrid.View.GetPropertyAccessProvider();
 
           
        if (MatchSearchTextOpimized("EmployeeId", dataRow))
            return true;
            
        return false;
    }
 
    protected virtual bool MatchSearchTextOpimized(string mappingName, object record)
    {
        if (this.DataGrid.View == null || string.IsNullOrEmpty(SearchText))
            return false;
 
        var cellvalue = Provider.GetFormattedValue(record, mappingName);
        if (this.SearchType == SearchType.Contains)
        {
            if (!AllowCaseSensitiveSearch)
                return cellvalue != null && cellvalue.ToString().ToLower().Contains(SearchText.ToString().ToLower());
            else
                return cellvalue != null && cellvalue.ToString().Contains(SearchText.ToString());
        }
        else if (this.SearchType == SearchType.StartsWith)
        {
            if (!AllowCaseSensitiveSearch)
                return cellvalue != null && cellvalue.ToString().ToLower().StartsWith(SearchText.ToString().ToLower());
            else
                return cellvalue != null && cellvalue.ToString().StartsWith(SearchText.ToString());
        }
        else
        {
            if (!AllowCaseSensitiveSearch)
                return cellvalue != null && cellvalue.ToString().ToLower().EndsWith(SearchText.ToString().ToLower());
            else
                return cellvalue != null && cellvalue.ToString().EndsWith(SearchText.ToString());
        }
    }
}
 

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        this.dataGrid.SearchHelper = new SearchHelperExt(this.dataGrid);
        this.TextBox.LostFocus += TextBox_LostFocus;
        this.TextBox.PreviewKeyDown += TextBox_PreviewKeyDown;
    }
    private void TextBox_LostFocus(object sender, RoutedEventArgs e)
    {
        PerformSearch();
    }
 
    private void TextBox_PreviewKeyDown(object sender, KeyEventArgs e)
    {
        if (e.Key == Key.Enter)
            PerformSearch();
    }
 
    private void PerformSearch()
    {
        if (this.dataGrid.SearchHelper.SearchText.Equals(this.TextBox.Text))
            return;
 
        var text = TextBox.Text;
        this.dataGrid.SearchHelper.AllowCaseSensitiveSearch = true;
        this.dataGrid.SearchHelper.SearchType = SearchType.StartsWith;
        this.dataGrid.SearchHelper.AllowFiltering = true;
        this.dataGrid.SearchHelper.Search(text);
    }
}