Making postback/AJAX request from user control
Generally UserControl does not implement IPostBackEventHandler. That is why, to achieve your goal you need to implement the following interface when needed. Here is the bare bone logic:
| C# |
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public class WebUserControl1 : System.Web.UI.UserControl, IPostBackEventHandler
{
public void RaisePostBackEvent(string eventArgument)
{
}
} |
| VB.NET |
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Public Class WebUserControl1
Inherits System.Web.UI.UserControl
Implements IPostBackEventHandler
Public Sub RaisePostBackEvent(ByVal eventArgument As String) Implements System.Web.UI.IPostBackEventHandler.RaisePostBackEvent
End Sub
End Class |
If you want to raise post-back event using __doPostBack() or RadGridClientObject.AjaxRequest() (i.e. in Telerik RadGrid in AJAX mode) you should use for eventTarget the UserControl.UniqueID. Below are two basic examples:
| Javascript [C#] |
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window["<%= RadGrid1.ClientID %>"].AjaxRequest("<%= this.UniqueID %>", "MyArgument"); |
| Javascript [VB.NET] |
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window["<%= RadGrid1.ClientID %>"].AjaxRequest("<%= Me.UniqueID %>", "MyArgument") |
Here is some info about these JavaScript functions:
|
__doPostBack(eventTarget, eventArgument)
or
RadGridClientObject.AjaxRequest(eventTarget, eventArgument) |
| eventTarget |
The control which should raise postback event. If this control is directly on the HtmlForm, you can use the control's UniqueID or ClientID. Otherwise if your control is in a INamingContainer, you must use the control's UniqueID. For UserControl you should use always the user control's UniqueID |
| eventArgument |
This is optional argument for the event, used for passing some data on the server (which can be processed further) |
Grid in Master page and RaisePostBackEvent handling
The approach is pretty much the same as with the user control - here is a sample scenario (note that we wired the
OnRowDblClick client event of the grid to call the
RadGridClientObject.AjaxRequest()method):
MasterPage.master
| ASPX |
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<head runat="server">
<title>Untitled Page</title>
<script type="text/javascript">
function RowDblClick(index)
{
grid.AjaxRequest("<%= this.UniqueID %>", "Rebind");
}
</script>
</head>
<body>
<form id="form1" runat="server">
<div>
<script type="text/javascript">
var grid;
function GridCreated()
{
grid = this;
}
</script>
<asp:ContentPlaceHolder ID="ContentPlaceHolder1" runat="server">
<rad:RadGrid ID="RadGrid1" DataSourceID="AccessDataSource1"
runat= "server" AutoGenerateColumns="True">
<MasterTableView DataSourceID="AccessDataSource1">
</MasterTableView>
<ClientSettings>
<ClientEvents OnGridCreated="GridCreated" OnRowDblClick="RowDblClick"></ClientEvents>
</ClientSettings>
</rad:RadGrid>
<asp:AccessDataSource ID="AccessDataSource1" DataFile="~/Nwind.mdb"
SelectCommand= "SELECT TOP 10 CustomerID, CompanyName, ContactName, ContactTitle,
Address, PostalCode FROM Customers" runat="server"></asp:AccessDataSource>
</asp:ContentPlaceHolder> |
MasterPage.master.cs
| C# |
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public partial class MasterPage : System.Web.UI.MasterPage, IPostBackEventHandler
{
public void RaisePostBackEvent(string eventArgument)
{
switch (eventArgument)
{
case "Rebind":
RadGrid1.Rebind();
break;
}
}
} |
| VB.NET |
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Public Class MasterPage
Inherits System.Web.UI.MasterPage
Implements IPostBackEventHandler
Public Sub RaisePostBackEvent(ByVal eventArgument As String)
Select Case (eventArgument)
Case "Rebind"
RadGrid1.Rebind
End Select
End Sub
End Class |
The same logic is applicable when your grid instance resides in an asp:Content control (under .NET 2.0) related to ContentPlaceHolder of MasterPage (asp: Content is INamingContainer).
As before, you should pass the UniqueID of your grid object as first parameter for the RadGridClientObject.AjaxRequest() method.
In the example below we attach script (which calls the RadGridClientObject.AjaxRequest() method) to checkbox with ID chkIsClosed in the checkbox PreRender handler:
| ASPX |
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<script type="text/javascript">
function PerformRequest()
{
window["<%= RadGrid1.ClientID %>"].AjaxRequest("<%= RadGrid1.UniqueID %>", "MyArgument");
}
</script>
<asp:Content ContentPlaceHolderID="ContentPlaceHolder1" ID="Holder1" runat="server">
<asp:CheckBox ID="chkIsClosed" runat="server" OnPreRender="chkIsClosed_PreRender" />
</asp:Content>
<asp:Content ContentPlaceHolderID = "ContentPlaceHolder2" ID="Holder2" runat="server">
<rad:radgrid id="RadGrid1" datasourceid="AccessDataSource1" runat="server"
EnableAJAX="true">
<MasterTableView DataSourceID="AccessDataSource1"></MasterTableView>
</rad:radgrid>
<asp:AccessDataSource ID="AccessDataSource1" DataFile="~/Nwind.mdb"
SelectCommand="SELECT TOP 10 CustomerID, CompanyName, ContactName, ContactTitle,
Address, PostalCode FROM Customers" runat="server"></asp:AccessDataSource>
</asp:Content> |
And in the code-behind:
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protected void chkIsClosed_PreRender(object source, System.EventArgs e)
{
(source as CheckBox).Attributes("onclick") = "PerformRequest()";
} |
| VB.NET |
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protected Sub chkIsClosed_PreRender(ByVal source as Object, ByVal e as System.EventArgs)
CType(source, CheckBox).Attributes("onclick") = "PerformRequest()"
End Sub |
Raising postback event from WebForm (overriding the default RaisePostBackEventHandler)
With a standard web form (aspx page) you can override the default RaisePostBackEventHandler and call its base.RaisePostBackEvent(source, eventArgument) method:
| C# |
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protected override void RaisePostBackEvent(IPostBackEventHandler source, String eventArgument)
{
base.RaisePostBackEvent(source, eventArgument);
switch(eventArgument)
{
case "Rebind":
RadGrid1.Rebind();
break;
}
} |
| VB.NET |
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Protected Overrides Sub RaisePostBackEvent(ByVal source As IPostBackEventHandler, ByVal eventArgument As String)
MyBase.RaisePostBackEvent(source, eventArgument)
Select Case (eventArgument)
Case "Rebind"
RadGrid1.Rebind
End Select
End Sub |
There are cases when you may want to update the information inside the grid by triggering a callback externally from other control on the page. Generally, this is a simple task with the integrated AJAX mechanism of Telerik RadGrid. You need to make a call to the RadGrid1.AjaxRequest() method (passing the necessary information as parameters to it) and then override the RaisePostBackEvent method to apply the changes. Here is a sample implementation:
| ASPX/ASCX |
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<rad:radgrid id="RadGrid1" runat="server"
EnableAJAX= "True" AllowSorting="True" AllowPaging="True">
</rad:radgrid>
<br />
<input type=button value="Refresh" onclick='window["<%= RadGrid1.ClientID %>"].AjaxRequest( "<%= RadGrid1.UniqueID%>", "Rebind")' /> |
In the code-behind:
| VB.NET |
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Protected Overrides Sub RaisePostBackEvent(ByVal source As IPostBackEventHandler, ByVal eventArgument As String)
MyBase.RaisePostBackEvent(source, eventArgument)
Select Case eventArgument
Case "Rebind"
RadGrid1.Rebind()
End Select
End Sub |
| C# |
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protected override void RaisePostBackEvent(IPostBackEventHandler source, String eventArgument)
{
base.RaisePostBackEvent(source, eventArgument);
switch(eventArgument)
{
case "Rebind":
RadGrid1.Rebind();
break;
}
} |