Binding Data to a Control

Up to now all of the examples that have painted the contents of a DataSet have done so by iterating through the DataTables.Rows collection for each DataTable inside the DataSet . This is non-ideal for several reasons:

• The burden of responsibility to paint the data manually every time there is an update in the DataSet contents falls on the developer.

• The process of painting into a ListBox is error prone.

• It is unwieldy to write code that paints only those DataRow s with certain RowState values.

• It is not easy to make the ListBox appealing to the eye when using it to display relational data.

The best solution to this problem is to use data binding, which connects a source of data to a consumer. The most popular source of data is the DataView because of its flexibility in filtering and sorting data automatically. The best-looking Winforms consumer of data is the DataGrid class, which is supported by the .NET Compact Framework in a limited way.

Binding to a DataGrid

When a DataSet is bound to a DataGrid , the contents of the DataSet automatically appear on the DataGrid in a visually pleasing format. To bind a DataSet to a DataGrid , follow these steps:

1. Create a DataView through the techniques discussed earlier in this chapter.

2. Create a new instance of a DataGrid . If you are using the Smart Device Extensions IDE, all you need to do is drag an instance of the DataGrid from the toolbar to the canvas of your project.

3. Set the DataGrid.DataSource property to the DataView you created in step 1.

DETAILS ABOUT THE DataGrid

Chapter 3 details the features of the DataGrid that are missing from the .NET Compact Framework. In the present chapter, though, we focus on the nuts and bolts of using the DataGrid to display data.

Although a brief overview of the DataGrid is provided here, it is treated in greater detail in Chapter 3. There you can learn how to alter the look, feel, and special behavior of the DataGrid . The DataGrid is a very slimmed-down version compared to the desktop's, so there are many issues advanced programmers should be aware of when using the DataGrid on the .NET Compact Framework.

The following sample code demonstrates how to bind a DataGrid with a DataView . It comes from the example application DataGrid_With_DataView:

 C# // Assuming that m_DataSet was already set up... m_sortAgeDataView = new DataView(m_DataSet.Tables[0]); m_sortAgeDataView.Sort = "Age DESC, Name DESC"; // Bind the DataGrid to our DataView and it will // automatically paint itself! dataGrid1.DataSource = m_sortAgeDataView; VB m_sortAgeDataView = New DataView(m_DataSet.Tables(0)) m_sortAgeDataView.Sort = "Age DESC, Name DESC" ' Bind the DataGrid to our DataView and it will ' automatically paint itself! Me.DataGrid1.DataSource = m_sortAgeDataView 

Using Data Binding in a Sample Application

The sample application named DataGrid_With_DataView demonstrates binding a DataView to a DataGrid in a complete stand-alone application. The project files for this application are located in the folder SampleApplications\Chapter6\ . There is a C# and a Visual Basic version.

DataGrid_With_DataView sets up a DataView using the same technique as was used in the DataView_Sort_And_Filter sample application. DataGrid_With_DataView uses only one DataView , which is sorted in descending order by age and name. Then, with just one line of code, the DataView binds to a DataGrid , and it displays automatically.