Programming Visual Basic .NET, Second Edition

Data Binding

Various technologies have offered programmers the opportunity to bind controls to data so that as the data is modified, the controls respond automatically. As Rocky used to say to Bullwinkle, “But that trick never works.” Bound controls often provided only limited control over their look and feel, and performance was usually pretty terrible. The ASP.NET designers set out to solve these problems and provide a suite of robust data-bound controls, which simplify display and modification of data, sacrificing neither performance nor control over the UI.

In the previous section, you hardcoded radio buttons onto a form, one for each of three Shippers in the Northwinds database. That can’t be the best way to do it; if you change the Shippers in the database, you have to go back and rewire the controls. This section shows how you can create these controls dynamically and then bind them to data in the database.

You might want to create the radio buttons based on data in the database because you can’t know at design time what text the buttons will have, or even how many buttons you’ll need. To accomplish this, use a RadioButtonList. RadioButtonList is a control that allows you to create radio buttons programatically; you provide the name and values for the buttons, and ASP.NET takes care of the plumbing.

Delete the radio buttons already on the form, and drag and drop a RadioButtonList in their place. Once it is there, you can use the Properties window to rename it to rbl1. ...