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Custom Editors Extending Auto-Generated Editors

You can create your own custom column editor class that extends one of the standard column editor base classes such as GridTextColumnEditor, GridDropDownColumnEditor, or GridBoolColumnEditor. You can then enhance the editing capabilities of your grid columns by replacing the auto-generated editor with an instance of your own custom editor.

There are two ways to attach a column editor to a column in your grid:

  • Declaratively, at design time (for styling purposes only).

  • In the code-behind, using the CreateColumnEditor event.

Attaching a custom column editor declaratively

In an ASPX file, you can attach an instance of your custom editor to a column by adding an instance to the page and setting the ColumnEditorID property of the column to the ID of the column editor:

<telerik:RadGrid RenderMode="Lightweight" ID="RadGrid1" runat="server" Width="97%" AutoGenerateColumns="False">
  <MasterTableView>
    <Columns>
      <telerik:GridBoundColumn ColumnEditorID="TextEditor1" DataField="ShipName" HeaderText="Ship name"
        UniqueName="ShipName">
      </telerik:GridBoundColumn>
      <telerik:GridEditCommandColumn />
    </Columns>
  </MasterTableView></telerik:RadGrid><br />
<telerik:GridTextBoxColumnEditor ID="TextEditor1" runat="server">
  <TextBoxStyle BackColor="#edffc3" BorderColor="#ecbb0d" BorderStyle="Solid" ForeColor="#7fa822" />
</telerik:GridTextBoxColumnEditor>

Using the CreateColumnEditor event

In a CreateColumnEditor event handler, you can attach an instance of your custom editor to a column by assigning the e.ColumnEditor parameter of the handler:

protected void RadGrid1_CreateColumnEditor(object sender, Telerik.Web.UI.GridCreateColumnEditorEventArgs e)
{
    GridBoundColumn column = e.Column as GridBoundColumn;
    if (column != null && column.DataField == "ShipAddress")
    {
        e.ColumnEditor = new MultiLineTextBoxColumnEditor(column);
    }
    if (column != null && column.DataField == "OrderDate")
    {
        e.ColumnEditor = new DateColumnEditor(column);
    }
}
Private Sub RadGrid1_CreateColumnEditor(ByVal sender As Object, ByVal e As Telerik.Web.UI.GridCreateColumnEditorEventArgs) Handles RadGrid1.CreateColumnEditor
    Dim column As GridBoundColumn = TryCast(e.Column, GridBoundColumn)
    If column IsNot Nothing AndAlso column.DataField = "ShipAddress" Then
        e.ColumnEditor = New MultiLineTextBoxColumnEditor(column)
    End If
    If column IsNot Nothing AndAlso column.DataField = "OrderDate" Then
        e.ColumnEditor = New DateColumnEditor(column)
    End If
End Sub

Implementing Custom Column Editors

When implementing a custom column editor, your editor class should extend GridColumnEditorBase, which implements the IColumnEditor interface. Depending on the type of data your column editor handles, it is a good idea to use GridTextColumnEditor, GridBoolColumnEditor, or GridDropDownColumnEditor as a base class, because these provide additional support for handling a particular type of data.

In the implementation of your column editor class, You must override the following methods:

  • LoadControlsFromContainer: This method is where your column editor should extract values from the TableCell of the grid and assign them to the controls it contains.

  • AddControlsToContainer: This method is where your column editor should create its child controls and add them to its Controls collection.

  • IsInitialized: This method should return a boolean value indicating whether it is fully loaded and bound, ready for use.

In addition, if you are using GridTextColumnEditor, GridBoolColumnEditor, or GridDropDownColumnEditor as a base class, you need to provide an implementation for the property that represents the edited value:

  • For GridTextColumnEditor, this is the Text property (of type String).

  • For GridBoolColumnEditor, this is the Value property (of type Boolean).

  • For GridDropDownColumnEditor, this includes both the SelectedText and SelectedValue properties (of type String).

note

Custom editors for each column should inherit the corresponding classes. For example to extend a RadGridBoundColumn's editor you need to inherit GridTextColumnEditor.

The example below shows the implementation of two custom column editor classes. Both custom editors extend the GridTextColumnEditor class and can be attached to a GridBoundColumn. The first represents an editor with multi-line textbox. The second handles DateTime values.

public class MultiLineTextBoxColumnEditor : GridTextColumnEditor
{
    private TextBox textBox;

    public MultiLineTextBoxColumnEditor(IGridEditableColumn owner)
    {
        base.SetOwner(owner);
    }

    protected override void LoadControlsFromContainer()
    {
        this.textBox = this.ContainerControl.Controls[0] as TextBox;
    }
    public override bool IsInitialized
    {
        get
        {
            return this.textBox != null;
        }
    }
    public override string Text
    {
        get
        {
            return this.textBox.Text;
        }
        set
        {
            this.textBox.Text = value;
        }
    }
    protected override void AddControlsToContainer()
    {
        this.textBox = new TextBox();
        this.textBox.TextMode = TextBoxMode.MultiLine;
        this.textBox.Rows = 4;
        this.textBox.Columns = 40;
        this.textBox.BackColor = Color.Crimson;
        this.textBox.ForeColor = Color.White;
        this.ContainerControl.Controls.Add(this.textBox);
    }
}

private class DateColumnEditor : GridTextColumnEditor
{
    private TextBox textBox;
    private CustomValidator validator;
    private RequiredFieldValidator reqValidator;

    public DateColumnEditor(IGridEditableColumn owner)
    {
        base.SetOwner(owner);
    }

    protected override void LoadControlsFromContainer()
    {
        this.textBox = this.ContainerControl.Controls[0] as TextBox;
    }
    public override bool IsInitialized
    {
        get
        {
            return this.textBox != null;
        }
    }
    public override string Text
    {
        get
        {
            return this.textBox.Text;
        }
        set
        {
            this.textBox.Text = value;
        }
    }
    protected override void AddControlsToContainer()
    {
        this.textBox = new TextBox();
        this.ContainerControl.Controls.Add(this.textBox);
        this.validator = new CustomValidator();
        this.textBox.ID = "tbDate";
        this.validator.ServerValidate += new ServerValidateEventHandler(this.ValidateDate);
        this.validator.ControlToValidate = this.textBox.ID;
        this.validator.ErrorMessage = " Please, enter a valid date";
        this.reqValidator = new RequiredFieldValidator();
        this.reqValidator.ErrorMessage = "This field is required.";
        this.reqValidator.ControlToValidate = this.textBox.ID;
        this.ContainerControl.Controls.Add(this.validator);
        this.ContainerControl.Controls.Add(this.reqValidator);
    }
    private void ValidateDate(object sender, ServerValidateEventArgs args)
    {
        try
        {
            string[] expectedFormats = { "d", "D", "f", "F", "G", "g" };
            DateTime.ParseExact(args.Value, expectedFormats, null, DateTimeStyles.AllowWhiteSpaces);
            args.IsValid = true;
        }
        catch (Exception ex)
        {
            args.IsValid = false;
            this.validator.Attributes["title"] = ex.Message;
        }
    }
}

Public Class MultiLineTextBoxColumnEditor
    Inherits GridTextColumnEditor
    Private textBox As TextBox

    Public Sub New(owner As IGridEditableColumn)
        MyBase.SetOwner(owner)
    End Sub

    Protected Overrides Sub LoadControlsFromContainer()
        Me.textBox = TryCast(Me.ContainerControl.Controls(0), TextBox)
    End Sub
    Public Overrides ReadOnly Property IsInitialized() As Boolean
        Get
            Return Me.textBox IsNot Nothing
        End Get
    End Property
    Public Overrides Property Text() As String
        Get
            Return Me.textBox.Text
        End Get
        Set(value As String)
            Me.textBox.Text = value
        End Set
    End Property
    Protected Overrides Sub AddControlsToContainer()
        Me.textBox = New TextBox()
        Me.textBox.TextMode = TextBoxMode.MultiLine
        Me.textBox.Rows = 4
        Me.textBox.Columns = 40
        Me.textBox.BackColor = Color.Crimson
        Me.textBox.ForeColor = Color.White
        Me.ContainerControl.Controls.Add(Me.textBox)
    End Sub
End Class

Private Class DateColumnEditor
    Inherits GridTextColumnEditor
    Private textBox As TextBox
    Private WithEvents validator As CustomValidator
    Private reqValidator As RequiredFieldValidator

    Public Sub New(owner As IGridEditableColumn)
        MyBase.SetOwner(owner)
    End Sub

    Protected Overrides Sub LoadControlsFromContainer()
        Me.textBox = TryCast(Me.ContainerControl.Controls(0), TextBox)
    End Sub
    Public Overrides ReadOnly Property IsInitialized() As Boolean
        Get
            Return Me.textBox IsNot Nothing
        End Get
    End Property
    Public Overrides Property Text() As String
        Get
            Return Me.textBox.Text
        End Get
        Set(value As String)
            Me.textBox.Text = value
        End Set
    End Property
    Protected Overrides Sub AddControlsToContainer()
        Me.textBox = New TextBox()
        Me.ContainerControl.Controls.Add(Me.textBox)
        Me.validator = New CustomValidator()
        Me.textBox.ID = "tbDate"
        Me.validator.ControlToValidate = Me.textBox.ID
        Me.validator.ErrorMessage = " Please, enter a valid date"
        Me.reqValidator = New RequiredFieldValidator()
        Me.reqValidator.ErrorMessage = "This field is required."
        Me.reqValidator.ControlToValidate = Me.textBox.ID
        Me.ContainerControl.Controls.Add(Me.validator)
        Me.ContainerControl.Controls.Add(Me.reqValidator)
    End Sub
    Private Sub ValidateDate(ByVal source As System.Object, _
 ByVal args As ServerValidateEventArgs) Handles validator.ServerValidate
        Try
            Dim expectedFormats As String() = {"d", "D", "f", "F", "G", "g"}
            DateTime.ParseExact(args.Value, expectedFormats, Nothing, DateTimeStyles.AllowWhiteSpaces)
            args.IsValid = True
        Catch ex As Exception
            args.IsValid = False
            Me.validator.Attributes("title") = ex.Message
        End Try
    End Sub
End Class

For a live example that demonstrates custom column editors, see Custom column editors.