Customize the Default Field Filter Editor

In case you need to slightly modify the default field filter editor that we have provided, you need to attach to the FieldFilterEditorCreated event. The event arguments provide the respective column instance and the editor that we have created in our factory. This event is fired after we have created and configured the editor in the factory and before displaying it in the UI so you get the chance to change its appearance.

Depending on the column DataType the editor will be different. For String columns you will get the StringFilterEditor, for DateTime columns you will get a RadDateTimePicker, for Enum columns you will get a RadComboBox, and for all other types you will get a plain TextBox. Here is an example of how to achieve that:

private void OnRadGridViewFieldFilterEditorCreated(object sender, Telerik.Windows.Controls.GridView.EditorCreatedEventArgs e) 
{ 
    if (e.Column.UniqueName == "HireDate") 
    { 
        Telerik.Windows.Controls.RadDateTimePicker picker = e.Editor as Telerik.Windows.Controls.RadDateTimePicker; 
        if (picker != null) 
        { 
            picker.InputMode = Telerik.Windows.Controls.InputMode.DateTimePicker; 
        } 
    } 
} 

Private Sub OnRadGridViewFieldFilterEditorCreated(sender As System.Object, e As Telerik.Windows.Controls.GridView.EditorCreatedEventArgs) 
    If e.Column.UniqueName = "HireDate" Then 
        Dim picker As Telerik.Windows.Controls.RadDateTimePicker = TryCast(e.Editor, Telerik.Windows.Controls.RadDateTimePicker) 
        If picker IsNot Nothing Then 
            picker.InputMode = Telerik.Windows.Controls.InputMode.DateTimePicker 
        End If 
    End If 
End Sub 

You can adjust anything on the stock field filter editor like this. If the default field filter editor control does not suit your needs you can replace it with a completely different control by following this article.

Filter as user types

In case you need the filtering to be re-applied on every character entered, you may consider using the following approach:

private void OnRadGridViewFieldFilterEditorCreated(object sender, Telerik.Windows.Controls.GridView.EditorCreatedEventArgs e) 
{ 
    var stringFilterEditor = e.Editor as StringFilterEditor; 
 
    if (stringFilterEditor != null) 
    { 
        e.Editor.Loaded += (s1, e1) => 
        { 
            var textBox = e.Editor.ChildrenOfType<TextBox>().Single(); 
            textBox.TextChanged += (s2, e2) => 
            { 
                textBox.GetBindingExpression(TextBox.TextProperty).UpdateSource(); 
            }; 
        }; 
    } 
} 

Private Sub OnRadGridViewFieldFilterEditorCreated(ByVal sender As Object, ByVal e As Telerik.Windows.Controls.GridView.EditorCreatedEventArgs) 
    Dim stringFilterEditor = TryCast(e.Editor, StringFilterEditor) 
 
    If stringFilterEditor IsNot Nothing Then 
        AddHandler e.Editor.Loaded, Sub(s1, e1) 
                                        Dim textBox = e.Editor.ChildrenOfType(Of TextBox)().Single() 
                                        AddHandler textBox.TextChanged, Sub(s2, e2) 
                                                                            textBox.GetBindingExpression(TextBox.TextProperty).UpdateSource() 
                                                                        End Sub 
                                    End Sub 
    End If 
End Sub