Using Web Parts in ASP.Net 2.0 - Web Parts Explained
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Web parts are basically beefed up panel controls. No, in fact, that’s exactly what they are, as the WebPart abstract class is actually derived from the Panel class! But instead of just the basic content holding block that is a panel, the Web Part has loads of additional interface elements as well as functionality, such as the ability to minimize and restore, as well as drag-and-drop.
Before I get into the code, I have to explain one more thing. You’re not actually going to implement a WebPart control on your page. As I mentioned, it’s an abstract class. So how do you get them on your page? Well, the simplest way is by creating user controls. These are contained in a collection of WebParts, by a control called a WebPartZone. The WebPartZone is also responsible for the layout of the WebPart(s) that it contains. You can have as many WebPartZones as you want on a page, containing many web parts. Of course, you can go through all the work of creating your own class by inheriting from the WebPart class, but it still needs to be wrapped in a WebPartZone. So, for the sake of simplicity, just use user controls!
You will also need to use a control called WebPartManager to manage all the WebParts on the page. Though it has no actual user interface, it is necessary to handle such things as remembering the visual state of the users’ WebParts.
So let’s assume that you’ve created two user controls, one that retrieves the weather, and one that retrieves stock quotes. I’m not going to detail the creation of these controls; you should be able to handle that yourself, or at least download some pre-built controls on the web to do this. I’m just going to show you how to register them on your page, and implement them as web parts. Here’s the code:
<%@ register tagprefix=”jc” tagname=”Weather” src=”weather.ascx” %>
<%@ register tagprefix=”jc” tagname=”Stocks” src=”stocks.ascx” %>
<%@ page language=”C#” %>
<html>
<head>
<title>webparts tutorial</title>
</head>
<body>
<form runat=”server” id=”Form1”>
<asp:WebPartManager runat=”server” id=”myWebMgr” />
<asp:WebPartZone runat=”server” id=”zone1”>
<ZoneTemplate>
<jc:Weather runat=”server” id=”myWeather” />
<jc:Stocks runat=”server” id=”myWeather” />
</ZoneTemplate>
</ asp:WebPartZone>
</form>
</body>
</html>
By looking as this code, it’s not readily apparent why I even bother throwing in all the extra code for the WebParts, when we could just toss the user controls right onto the page. However, by wrapping them in WebParts, we achieve some extra "stuff." By default, the WebPartZone will now throw a border and title on your WebParts (user controls) as defined in your site defaults. But very importantly, now you’re also given runtime rendering options. As in: each control displays two options: "minimize" and "close."
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