CS 112D Lecture Notes - Data Binding

Data Binding

• Data Binding - linking visual controls with data fields so data is automatically displayed for the current record and user changes are automatically saved.
• Data binding is covered briefly in Chapter 1 of our textbook, but much more info on it is available in the book, ADO.NET Programming in Visual Basic .NET by Steve Holzner and Bob Howell, Prentice Hall, 2003. (Which is slightly more advanced than our textbook)
• To bind a TextBox to a DataSet in code, call the Add method of the DataBindings property of the TextBox like one of the following two examples:

      txtLastName.DataBindings.Add(New System.Windows.Forms.Binding("Text", dsNovelty, "Employee.LastName"))
      'above is form-designer-generated format, below is equivalent:
      txtLastName.DataBindings.Add("Text", dsNovelty, "Employee.LastName")
      

  In the above example, txtLastName is a TextBox, dsNovelty is a DataSet, Employee is the name of a DataTable in that DataSet, and LastName is the name of the field in that DataTable that we want displayed in the TextBox.
• CurrencyManager - a class which inherits from the BindingManagerBase class. A CurrencyManager object manages all the associations between a DataTable and its bound controls.
• To access the CurrencyManager for a form, use the BindingContext property, specifying which DataTable's CurrencyManager you want.
• A form with data-bound controls can be automatically set up for you by the Data Form Wizard, which is available from the "Add New Item" dialog - instead of selecting "Windows Form", select "Data Form Wizard"
• This wizard can setup a form with data from up to two tables in a master-detail relationship, using a DataGrid or TextBoxes combined with a DataGrid.

New Ways of Data Binding in VS 2005

• In Visual Studio 2005 (.NET Framework 2.0) the above will all still work, but new classes have been added to the framework to make data binding easier. The most important ones are BindingSource and BindingNavigator.
• BindingSource takes the place of the CurrencyManager / Binding Context.
• This BindingSource Component Overview summarizes how to use the BindingSource and its properties and methods
• This BindingSource class documentation provides more details and focuses on code-writing
• a BindingNavigator is generally used with a BindingSource to provide a navigation toolbar. This BindingNavigator Control Overview summarizes how to use it.

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