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Custom Editors

RadTreeList provides a straightforward way to specify a non-default editor for an editable column. The RadTreeList.CreateColumnEditor event fires whenever a column editor needs to be initialized.

The event argument object of type TreeListCreateColumnEditorEventArgs provides the following properties:

  • Column - the TreeListEditableColumn instance for which a column editor will be initialized.

  • DefaultEditor - the default ITreeListColumnEditor instance that the column provides.

  • CustomEditorInitializer - a delegate that does not accept parameters and returns an instance of type ITreeListColumnEditor.

Custom Column Editors

The user is expected to provide a delegate function to e.CustomEditorInitializer that instantiates and returns an ITreeListColumnEditor object.A column editor instance usually accepts the target editable column in its constructor. With the following sample code, we provide a custom column editor for the "Notes" column in the RadTreeList:

<telerik:RadTreeList RenderMode="Lightweight" runat="server" ID="RadTreeList1" OnCreateColumnEditor="RadTreeList1_CreateColumnEditor"
    DataSourceID="SqlDataSource1" AutoGenerateColumns="false" DataKeyNames="EmployeeID" ParentDataKeyNames="ReportsTo">
    <Columns>
        <telerik:TreeListBoundColumn DataField="EmployeeID" HeaderStyle-Width="60px" HeaderText="EmployeeID"
            UniqueName="EmployeeID" ReadOnly="true">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListBoundColumn DataField="LastName" HeaderText="Last Name" HeaderStyle-Width="60px"
            UniqueName="LastName">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListBoundColumn DataField="FirstName" HeaderText="First Name" HeaderStyle-Width="60px"
            UniqueName="FirstName">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListBoundColumn DataField="TitleOfCourtesy" HeaderText="Title of courtesy"
            HeaderStyle-Width="60px" UniqueName="Title">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListBoundColumn DataField="Notes" HeaderText="Notes" UniqueName="Notes">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListBoundColumn DataField="ReportsTo" HeaderText="ReportsTo" HeaderStyle-Width="65px"
            UniqueName="ReportsTo" ReadOnly="true" ForceExtractValue="Always">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListEditCommandColumn UniqueName="EditColumn" HeaderStyle-Width="57px"
            ButtonType="ImageButton">
        </telerik:TreeListEditCommandColumn>
    </Columns>
</telerik:RadTreeList>

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
DeleteCommand="DELETE FROM [Employees] WHERE [EmployeeID] = @EmployeeID" InsertCommand="INSERT INTO [Employees] ([LastName], [FirstName], [TitleOfCourtesy], [Notes], [ReportsTo]) VALUES (@LastName, @FirstName, @TitleOfCourtesy, @Notes, @ReportsTo)"
SelectCommand="SELECT [EmployeeID], [LastName], [FirstName], [TitleOfCourtesy], [Notes], [ReportsTo] FROM [Employees]"
UpdateCommand="UPDATE [Employees] SET [LastName] = @LastName, [FirstName] = @FirstName, [TitleOfCourtesy] = @TitleOfCourtesy, [Notes] = @Notes, [ReportsTo] = @ReportsTo WHERE [EmployeeID] = @EmployeeID">
<DeleteParameters>
    <asp:Parameter Name="original_EmployeeID" Type="Int32" />
</DeleteParameters>
<UpdateParameters>
    <asp:Parameter Name="LastName" Type="String" />
    <asp:Parameter Name="FirstName" Type="String" />
    <asp:Parameter Name="TitleOfCourtesy" Type="String" />
    <asp:Parameter Name="Notes" Type="String" />
    <asp:Parameter Name="ReportsTo" Type="Int32" />
    <asp:Parameter Name="EmployeeID" Type="Int32" />
</UpdateParameters>
<InsertParameters>
    <asp:Parameter Name="LastName" Type="String" />
    <asp:Parameter Name="FirstName" Type="String" />
    <asp:Parameter Name="TitleOfCourtesy" Type="String" />
    <asp:Parameter Name="Notes" Type="String" />
    <asp:Parameter Name="ReportsTo" Type="Int32" />
</InsertParameters>
</asp:SqlDataSource>
<asp:SqlDataSource runat="server" ID="SqlDataSource2" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
SelectCommand="SELECT DISTINCT [TitleOfCourtesy] FROM [Employees]"></asp:SqlDataSource>
protected void RadTreeList1_CreateColumnEditor(object sender, TreeListCreateColumnEditorEventArgs e)
{
    if (e.Column.DataField == "Notes")
    {
        TreeListTextBoxColumnEditor notesEditor = e.DefaultEditor as TreeListTextBoxColumnEditor;
        notesEditor.TextBoxControl.TextMode = TextBoxMode.MultiLine;
        notesEditor.TextBoxControl.Rows = 10;

    }
}
Protected Sub RadTreeList1_CreateColumnEditor(ByVal sender As Object, ByVal e As TreeListCreateColumnEditorEventArgs)

    If e.Column.DataField = "Notes" Then
        Dim notesEditor As TreeListTextBoxColumnEditor = TryCast(e.DefaultEditor, TreeListTextBoxColumnEditor)
        notesEditor.TextBoxControl.TextMode = TextBoxMode.MultiLine

        notesEditor.TextBoxControl.Rows = 10
    End If
End Sub

Implementing Custom Editors

To create a custom column editor, a developer needs to implement the ITreeListColumnEditor in a class.By convention, a column editor in RadTreeList does not have a default parameter-less constructor and accepts the TreeListEditableColumn instance in its constructor. Even though this is not a strict requirement for a custom column editor, this provides direct access to the editable column that the column editor will work for. The editor can then read settings from the column and apply them to edit controls initialized in the cells of the edited items.The example bellow demonstrates implementig of Custom Editor for the "TitleOfCourtesy" TreeList column:

<telerik:RadTreeList RenderMode="Lightweight" runat="server" ID="RadTreeList1" OnCreateColumnEditor="RadTreeList1_CreateColumnEditor"
    DataSourceID="SqlDataSource1" AutoGenerateColumns="false" DataKeyNames="EmployeeID" ParentDataKeyNames="ReportsTo">
    <Columns>
        <telerik:TreeListBoundColumn DataField="EmployeeID" HeaderStyle-Width="60px" HeaderText="EmployeeID"
            UniqueName="EmployeeID" ReadOnly="true">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListBoundColumn DataField="LastName" HeaderText="Last Name" HeaderStyle-Width="60px"
            UniqueName="LastName">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListBoundColumn DataField="FirstName" HeaderText="First Name" HeaderStyle-Width="60px"
            UniqueName="FirstName">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListBoundColumn DataField="TitleOfCourtesy" HeaderText="Title of courtesy"
            HeaderStyle-Width="60px" UniqueName="Title">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListBoundColumn DataField="Notes" HeaderText="Notes" UniqueName="Notes">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListBoundColumn DataField="ReportsTo" HeaderText="ReportsTo" HeaderStyle-Width="65px"
            UniqueName="ReportsTo" ReadOnly="true" ForceExtractValue="Always">
        </telerik:TreeListBoundColumn>
        <telerik:TreeListEditCommandColumn UniqueName="EditColumn" HeaderStyle-Width="57px"
            ButtonType="ImageButton">
        </telerik:TreeListEditCommandColumn>
    </Columns>
</telerik:RadTreeList>

<asp:SqlDataSource ID="SqlDataSource1" runat="server" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
DeleteCommand="DELETE FROM [Employees] WHERE [EmployeeID] = @EmployeeID" InsertCommand="INSERT INTO [Employees] ([LastName], [FirstName], [TitleOfCourtesy], [Notes], [ReportsTo]) VALUES (@LastName, @FirstName, @TitleOfCourtesy, @Notes, @ReportsTo)"
SelectCommand="SELECT [EmployeeID], [LastName], [FirstName], [TitleOfCourtesy], [Notes], [ReportsTo] FROM [Employees]"
UpdateCommand="UPDATE [Employees] SET [LastName] = @LastName, [FirstName] = @FirstName, [TitleOfCourtesy] = @TitleOfCourtesy, [Notes] = @Notes, [ReportsTo] = @ReportsTo WHERE [EmployeeID] = @EmployeeID">
<DeleteParameters>
    <asp:Parameter Name="original_EmployeeID" Type="Int32" />
</DeleteParameters>
<UpdateParameters>
    <asp:Parameter Name="LastName" Type="String" />
    <asp:Parameter Name="FirstName" Type="String" />
    <asp:Parameter Name="TitleOfCourtesy" Type="String" />
    <asp:Parameter Name="Notes" Type="String" />
    <asp:Parameter Name="ReportsTo" Type="Int32" />
    <asp:Parameter Name="EmployeeID" Type="Int32" />
</UpdateParameters>
<InsertParameters>
    <asp:Parameter Name="LastName" Type="String" />
    <asp:Parameter Name="FirstName" Type="String" />
    <asp:Parameter Name="TitleOfCourtesy" Type="String" />
    <asp:Parameter Name="Notes" Type="String" />
    <asp:Parameter Name="ReportsTo" Type="Int32" />
</InsertParameters>
</asp:SqlDataSource>
<asp:SqlDataSource runat="server" ID="SqlDataSource2" ConnectionString="<%$ ConnectionStrings:NorthwindConnectionString %>"
SelectCommand="SELECT DISTINCT [TitleOfCourtesy] FROM [Employees]"></asp:SqlDataSource>
protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            RadTreeList1.ExpandedIndexes.Add(new TreeListHierarchyIndex { LevelIndex = 0, NestedLevel = 0 });
        }
    }
    protected void RadTreeList1_CreateColumnEditor(object sender, TreeListCreateColumnEditorEventArgs e)
    {
        if (e.Column.DataField == "TitleOfCourtesy")
        {
            e.CustomEditorInitializer = new TreeListCreateCustomEditorDelegate(delegate
            {
                TreeListComboEditor editor = new TreeListComboEditor(e.Column);
                editor.ComboBox.DataSourceID = "SqlDataSource2";
                editor.ComboBox.DataTextField = "TitleOfCourtesy";
                editor.ComboBox.DataValueField = "TitleOfCourtesy";

                return editor;
            });
        }

    }
}
public class TreeListComboEditor : TreeListColumnEditor
{
    public TreeListComboEditor(TreeListEditableColumn column)
        : base(column)
    {
        InitializeCombo();
    }

    public RadComboBox ComboBox
    {
        get;
        private set;
    }

    protected virtual void InitializeCombo()
    {
        ComboBox = new RadComboBox();
        ComboBox.ID = base.GenerateControlID();
    }

    public override IEnumerable GetValues()
    {
        yield return ComboBox.SelectedValue;
    }

    public override void Initialize(TreeListEditableItem editItem, Control container)
    {
        container.Controls.Add(ComboBox);
    }

    public override void SetValues(IEnumerable values)
    {
        object value = TreeListColumnEditor.GetFirstValueFromEnumerable(values);
        if (value != null)
        {
            ComboBox.SelectedValue = value.ToString();
        }
    }
}
Protected Sub RadTreeList1_CreateColumnEditor(ByVal sender As Object, ByVal e As TreeListCreateColumnEditorEventArgs)
    If e.Column.DataField = "TitleOfCourtesy" Then
        Dim editor As TreeListComboEditor = New TreeListComboEditor(e.Column)
        editor.ComboBox.DataSourceID = "SqlDataSource2"
        editor.ComboBox.DataTextField = "TitleOfCourtesy"
        editor.ComboBox.DataValueField = "TitleOfCourtesy"
        e.CustomEditorInitializer = New TreeListCreateCustomEditorDelegate(Function() editor)
    End If
End Sub

Public Class TreeListComboEditor
    Inherits TreeListColumnEditor
    Public Sub New(ByVal column As TreeListEditableColumn)
        MyBase.New(column)
        InitializeCombo()
    End Sub

    Public Property ComboBox() As RadComboBox
        Get
            Return m_ComboBox
        End Get
        Private Set(ByVal value As RadComboBox)
            m_ComboBox = value
        End Set
    End Property
    Private m_ComboBox As RadComboBox

    Protected Overridable Sub InitializeCombo()
        ComboBox = New RadComboBox()
        ComboBox.ID = MyBase.GenerateControlID()
    End Sub

    Public Overrides Function GetValues() As IEnumerable
        Return (ComboBox.SelectedValue)
    End Function

    Public Overrides Sub Initialize(ByVal editItem As TreeListEditableItem, ByVal container As Control)
        container.Controls.Add(ComboBox)
    End Sub

    Public Overrides Sub SetValues(ByVal values As IEnumerable)
        Dim value As Object = TreeListColumnEditor.GetFirstValueFromEnumerable(values)
        If value IsNot Nothing Then
            ComboBox.SelectedValue = value.ToString()
        End If
    End Sub
End Class

Alternatively to implementing the ITreeListColumnEditor interface, a developer can decide to subclass from the abstract TreeListColumnEditor class that provides some handy properties and methods.

See Also