public void RegisterDataItem (
Public Sub RegisterDataItem ( _
control As Control, _
dataItem As String, _
isJsonSerialized As Boolean _
void RegisterDataItem (
- control (Control)
The page control that is receiving the data.
- dataItem (String)
The data that is sent to the control.
- isJsonSerialized (Boolean)
A Boolean value that indicates whether dataItem is serialized as JSON.
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 have registered for the control parameter is not serialized as JSON, set the isJsonSerialized parameter to false. This avoids the need to use the eval Method (JScript) 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 with the RegisterDataItem method can be accessed in client script in the pageLoading, pageLoaded, and endRequest events of the PageRequestManager class. When you provide a handler for these events, custom data is passed with an event argument object where you can access the data items. For example, if you provide a handler for the pageLoading event, the custom data is passed with the PageLoadingEventArgs object, which exposes a dataItems 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 of an UpdatePanel control. Additionally, this example demonstrates the overload that does not take the isJsonSerialized parameter. Otherwise, the procedure for retrieving the dataItems property of the PageLoadingEventArgs object is the same.
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 of an UpdatePanel control.
Assembly: System.Web.Extensions (Module: System.Web.Extensions)