6.3. Creating a Custom Control with State
You want to create a custom control that remembers its state between
postbacks of a form, like the server controls provided with ASP.NET.
Create a custom control like the one described in Recipe 6.2, implement the
IPostBackDataHandler interface to add the functionality to retrieve the values posted to the server and then update the values in the custom control from the
Use the .NET language of your choice to:
Create a class that inherits from the
WebControlclass in the
Implement support for HTML-style attributes by adding properties to the class.
IPostBackDataHandleras necessary to update the state of the control with the posted data.
RenderContentsmethod to have it render the HTML output of the control using the values of the properties.
To use the custom control in an ASP.NET page:
Register the assembly containing the control.
Insert the tag for the custom control anywhere in the page and set the attributes appropriately.
A version of the custom control that maintains state and provides the added ability to raise an event when the control data has changed is shown in Examples 6-10 (VB) and 6-11 (C#). Examples 6-12, 6-13 through 6-14 show the .aspx and code-behind files of an application that ...