Update in Composite Control

This topic demonstrates a possible scenario of RadAjaxManager updates controls from a composite control. It is important to set IDs of instantiated controls as well as adding them into controls collection. A necessary AJAX setting could be added at CreateChildControls method, however this must be done after controls are added into corresponding controls collection.

The example below includes a single RadAjaxManager control on the page. Here is the code-behind:

TestComposite Tst1;

protected void Page_Load(object sender, EventArgs e)
{
           Tst1 = new TestComposite(RadAjaxManager1, "1");
           //set an ID of instantiated control!
           Tst1.ID = "tst1";
           this.form1.Controls.Add(Tst1);
}

protected void RadAjaxManager1_AjaxRequest(object sender, Telerik.Web.UI.AjaxRequestEventArgs e)
{
           //Update control from the composite on AJAX request
           Tst1.controLbl.Text = Tst1.controTB.Text;
}

Private Tst1 As TestComposite

Protected Sub Page_Load(ByVal sender As Object, ByVal e As EventArgs)
            Tst1 = New TestComposite(RadAjaxManager1, "1")
            'set an ID of instantiated control!
            Tst1.ID = "tst1"
            Me.form1.Controls.Add(Tst1)
End Sub

Protected Sub RadAjaxManager1_AjaxRequest(ByVal sender As Object, ByVal e As Telerik.Web.UI.AjaxRequestEventArgs)
            'Update control from the composite on AJAX request
            Tst1.controLbl.Text = Tst1.controTB.Text
End Sub

And the composite control class:

public class TestComposite : CompositeControl
{
            private Telerik.Web.UI.RadAjaxManager m_radAm;
            private string m_UniqueId;
            public TextBox MyTxt;
            public Label MyLbl;

public TestComposite(RadAjaxManager radAm, string UniqueId)
{
                m_radAm = radAm;
                m_UniqueId = UniqueId;


protected override void RecreateChildControls()
{
                EnsureChildControls();
}

protected override void CreateChildControls()
{
                MyTxt = new TextBox();
                MyLbl = new Label();

                //set IDs of instantiated controls!
                MyLbl.ID = "Lbl_" + m_UniqueId;
                MyTxt.ID = "Txt_" + m_UniqueId;

                MyLbl.Text = "LabelText";

                //add the controls into controls collection!
                this.Controls.Add(MyTxt);
                this.Controls.Add(MyLbl);

                //Manually add AJAX request triggered on onBlur client event of the text box
                MyTxt.Attributes.Add("onBlur", m_radAm.GetAjaxEventReference(MyTxt.ClientID));

                //Add the ajax setting - this should be done after controls are added into controls collection
                m_radAm.AjaxSettings.AddAjaxSetting(m_radAm, MyLbl);
}

public TextBox controTB
{
                get
                {
                    return MyTxt;
                }
}

public Label controLbl
{
                get
                {
                    return MyLbl;
                }
}

protected override void Render(HtmlTextWriter output)
{
                base.Render(output);

                MyTxt.RenderControl(output);
                MyLbl.RenderControl(output);

}
}  

Public Class TestComposite
            Inherits CompositeControl
            Private m_radAm As Telerik.Web.UI.RadAjaxManager
            Private m_UniqueId As String
            Public MyTxt As TextBox
            Public MyLbl As Label

Public Sub New(ByVal radAm As RadAjaxManager, ByVal UniqueId As String)
                m_radAm = radAm
                m_UniqueId = UniqueId
End Sub

Protected Overrides Sub RecreateChildControls()
                EnsureChildControls()
End Sub

Protected Overrides Sub CreateChildControls()
                MyTxt = New TextBox()
                MyLbl = New Label()

                'set IDs of instantiated controls!
                MyLbl.ID = "Lbl_" + m_UniqueId
                MyTxt.ID = "Txt_" + m_UniqueId

                MyLbl.Text = "LabelText"

                'add the controls into controls collection!
                Me.Controls.Add(MyTxt)
                Me.Controls.Add(MyLbl)

                'Manually add AJAX request triggered on onBlur client event of the text box
                MyTxt.Attributes.Add("onBlur", m_radAm.GetAjaxEventReference(MyTxt.ClientID))

                'Add the ajax setting - this should be done after controls are added into controls collection
                m_radAm.AjaxSettings.AddAjaxSetting(m_radAm, MyLbl)
End Sub

Public ReadOnly Property controTB() As TextBox
                Get
                    Return MyTxt
                End Get
End Property

Public ReadOnly Property controLbl() As Label
                Get
                    Return MyLbl
                End Get
End Property

Protected Overrides Sub Render(ByVal output As HtmlTextWriter)
                MyBase.Render(output)

                MyTxt.RenderControl(output)
                MyLbl.RenderControl(output)

End Sub
End Class

See Also

• Manually Add an AJAX Request