Mega Code Archive
Adding an asynchronous callback to validate data (VB)
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Imports System.ComponentModel
Imports System.Web.UI
<DefaultProperty("Text"), _
ToolboxData("<{0}:WebCustomControl1 runat=server></{0}:WebCustomControl1>")> _
Public Class WebCustomControl1
Inherits System.Web.UI.WebControls.WebControl
Implements System.Web.UI.ICallbackEventHandler
Dim _text As String
<Bindable(True), Category("Appearance"), Themeable(False), DefaultValue("")> _
Property [Text]() As String
Get
Return _text
End Get
Set(ByVal Value As String)
_text = Value
End Set
End Property
Protected Overrides Sub Render(ByVal output As System.Web.UI.HtmlTextWriter)
output.RenderBeginTag(HtmlTextWriterTag.Div)
output.AddAttribute(HtmlTextWriterAttribute.Type, "text")
output.AddAttribute(HtmlTextWriterAttribute.Id, Me.ClientID)
output.AddAttribute(HtmlTextWriterAttribute.Name, Me.ClientID)
output.AddAttribute(HtmlTextWriterAttribute.Value, Me.Text)
output.AddAttribute("OnBlur", "ClientCallback();")
Me.AddAttributesToRender(output)
output.RenderBeginTag(HtmlTextWriterTag.Input)
output.RenderEndTag()
output.RenderEndTag()
End Sub
Protected Overrides Sub OnPreRender(ByVal e As System.EventArgs)
Page.ClientScript.RegisterStartupScript(GetType(Page), _
"ControlFocus", "document.getElementById('" & Me.ClientID & "').focus();", _
True)
Page.ClientScript.RegisterStartupScript( _
GetType(Page), "ClientCallback", _
"function ClientCallback() {" & _
"args=document.getElementById('" & Me.ClientID & "').value;" & _
Page.ClientScript.GetCallbackEventReference(Me, "args", _
"CallbackHandler", Nothing, "ErrorHandler", True) + "}", _
True)
End Sub
Public Sub RaiseCallbackEvent(ByVal eventArgument As String) Implements System.Web.UI.ICallbackEventHandler.RaiseCallbackEvent
Dim result As Int32
If (Not Int32.TryParse(eventArgument, result)) Then
Throw New Exception("The method or operation is not implemented.")
End If
End Sub
Public Function GetCallbackResult() As String Implements ICallbackEventHandler.GetCallbackResult
Return "Valid Data"
End Function
End Class
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