ScriptManager.RegisterDataItem Method (Control, String, Boolean)


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Sends custom data to a control during partial-page rendering, and indicates whether the data is in JavaScript Object Notation (JSON) format.

Namespace:   System.Web.UI
Assembly:  System.Web.Extensions (in System.Web.Extensions.dll)

public void RegisterDataItem(
	Control control,
	string dataItem,
	bool isJsonSerialized


Type: System.Web.UI.Control

The page control that is receiving the data.

Type: System.String

The data that is sent to the control.

Type: System.Boolean

true to indicate that dataItem is serialized as JSON; otherwise, false.

Exception Condition

control is null.


The RegisterDataItem method is called during a postback.


dataItem is already registered for control.

You use the RegisterDataItem method to send data from the server to the client during asynchronous postbacks, regardless of whether the control receiving the data is inside an UpdatePanel control.

If the dataItem parameter that you register for control is not serialized as JSON, set the isJsonSerialized parameter to false. This avoids the need to use the function for each string that is sent to the client. For more information about the JSON format, see the Introducing JSON Web site.

The RegisterDataItem method can be called only during an asynchronous postback. To determine whether a postback is asynchronous, use the IsInAsyncPostBack property.

The data items that are registered by using the RegisterDataItem method can be accessed in client script during the , , and events of the object. When you handle these events, the custom data is passed in an event argument object. For example, if you provide a handler for the event, the custom data is passed in the class, which exposes a property.

The following example shows how to send data to two Label controls on a page during an asynchronous postback. The Label controls are not inside an UpdatePanel control. This example shows the overload that does not take the isJsonSerialized parameter. Otherwise, the procedure for retrieving the property of the object is the same as if you did not use that overload.


The data that is sent in this example is for illustration only. In a real-world application, you would use the RegisterDataItem method to send custom data from the server. For example, you could use the data item to send information about whether to hide or show client elements that are not inside an UpdatePanel control.

<%@ Page Language="C#" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 

<script runat="server">

    protected void Page_Load(object sender, EventArgs e)
        if (ScriptManager1.IsInAsyncPostBack)
            System.Web.Script.Serialization.JavaScriptSerializer json =
                new System.Web.Script.Serialization.JavaScriptSerializer();
            ScriptManager1.RegisterDataItem(Label1, DateTime.Now.ToString());
            ScriptManager1.RegisterDataItem(Label2, json.Serialize("more data"), true);

<html xmlns="" >
<head runat="server">
    <title>ScriptManager RegisterDataItem Example</title>
    <form id="form1" runat="server">
    <asp:ScriptManager ID="ScriptManager1" runat="server" />
    <script type="text/javascript" language="javascript">
        function PageLoadingHandler(sender, args) {
            var dataItems = args.get_dataItems();
            if ($get('Label1') !== null)
                $get('Label1').innerHTML = dataItems['Label1'];
            if ($get('Label2') !== null)
                $get('Label2').innerHTML = dataItems['Label2'];
    <asp:UpdatePanel ID="UpdatePanel1" UpdateMode="Conditional" runat="server">
       UpdatePanel content.
       <asp:Button ID="Button1" Text="Submit" runat="server" />
    <hr />
    <asp:Label ID="Label1" runat="server" /> <br />
    <asp:Label ID="Label2" runat="server" />

.NET Framework
Available since 3.5
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