Master Pages in ASP.net(Helpful for beginers)

A professional web site will have a standardized look across all pages. For example, one popular layout type places a navigation menu on the left side of the page, a copyright on the bottom, and content in the middle. It can be difficult to maintain a standard look if you must always put the common pieces in place with every webform you build. In ASP.NET 2.0, master pages will make the job easier. You’ll only need to write the common pieces once - in the master page. A master page can serve as a template for one or more web forms. Each ASPX web form only needs to define the content unique to itself, and this content will plug into specified areas of the master page layout.



CONFIGURING MASTERPAGES
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To add a master page to a web project, right-click your web project in the Solution Explorer window, select Add New Item, and select the Master Page item type from the Add New Item dialog. The listing below shows a sample master page in source view.

A master page looks very similar to an ASPX file, except a master page will have a .master file extension instead of a .aspx extension, and uses an @ Master directive instead of an @ Page directive at the top. Master pages will define the html, head, body, and form, tags. A new control, the ContentPlaceHolder control also appears in our master page. You can have one or more ContentPlaceHolder controls in a master page. ContentPlaceHolder controls are where we want our ASPX web forms to place their content.

Just like any ASPX form, our master page can contain code in a script block, or in a code-behind file, and can respond to page lifecycle events. The MasterPage class (from the System.Web.UI namespace) derives from UserControl and will have all of the usual events: Init, Load, PreRender, etc. The following listing shows how we’ve added a Page_Load event handler to modify the color of the menu control on the page, and we’ve also added a property to allow setting and retrieving the text inside the footer.

Master Pages and Configuration

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There are three ways to associate a web form with a master page. You can use the Master attribute in the @ Page directive, and you can write to the MasterPageFile property in the PreInit event or earlier. We’ve seen examples of both of these techniques. Any web form using the Master attribute of the @ Page directive or setting the MasterPageFile property programmatically will override the web.config settings.

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