ASP.NET Tip: Selecting a Master Page at Runtime

Master pages, introduced with ASP.NET 2.0, provide developers an easy way to create a shared layout for a site or portion of a site without having to work around Visual Studio .NET. While many sites will have a master page specified in each page by default, you can also design your site to select a master page dynamically. For example, an application I've created contains two master pages. Which one the user sees depends on which hostname he or she uses to visit the site. I do this so that the graphics and text are appropriate for the domain, but I have a single Web site servicing both domains behind the scenes.

The trick to selecting a master page at runtime is to add code into the OnPreInit event handler of your Web page. This is the point at which you can select the master page to be used for the particular Web page. For instance, you might have code that looks like this:

protected override void OnPreInit(EventArgs e)
{
   base.OnPreInit(e);
   if (Request.Url.Host.Contains("test.com"))
      base.MasterPageFile = Server.MapPath("test.com.master");
   else
      base.MasterPageFile = Server.MapPath("test2.com.master");
}

The MasterPageFile property requires a pathname and not a URL reference. However, you can always use Server.MapPath to convert your URL into an actual filename.

This feature works quite well for the content management system I've built. Use it to allow a page to choose a different look on the fly, based on whatever criteria you choose.

About the Author

Eric Smith is the owner of Northstar Computer Systems, a Web-hosting company based in Indianapolis, Indiana. He is also a MCT and MCSD who has been developing with .NET since 2001. In addition, he has written or contributed to 12 books covering .NET, ASP, and Visual Basic. Send him your questions and feedback via e-mail at questions@techniquescentral.com.



Comments

  • There are no comments yet. Be the first to comment!

Leave a Comment
  • Your email address will not be published. All fields are required.

Top White Papers and Webcasts

  • Cisco and Intel have harnessed flash memory technology and truly innovative system software to blast through the boundaries of today's I/O-bound server/storage architectures. See how they are bringing real-time responsiveness to data-intensive applications—for unmatched business advantage. Sponsored by Cisco and Intel® Partnering in Innovation

  • Corporate e-Learning technology has a long and diverse pedigree. As far back as the 1980s, companies were adopting computer-based training to supplement traditional classroom activities. More recently, rich web-based applications have added streaming audio and video, real-time collaboration and other new tools to the e-Learning mix. At the same time, the growing availability of informal learning tools--a category that includes everything from web searches to social media posts--are having a major impact on …

Most Popular Programming Stories

More for Developers

Latest Developer Headlines

RSS Feeds