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Example 7

This example illustrates data binding using a vector of namespaces.

Each row in the WPF DataGrid control is represented by an object, and each column as a property of that object. Each row in the DataGrid is bound to an object in the data source, and each column in the data grid is bound to a property of the data object.

data binding datagrid1
Figure 1: data binding datagrid1

The XAML

The XAML shown below, describes a Window containing a DockPanel, inside which is a DataGrid. 

 <Window
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="DataGrid Example" Height="500"
    SizeToContent="Width"
    Topmost="true">
    <DockPanel>
        <DataGrid Name="DG1" ItemsSource="{Binding}"
                  AutoGenerateColumns="False" >
            <DataGrid.Columns>
                <DataGridTextColumn Header="Wine"
                 Binding="{Binding Name}"/>
                <DataGridTextColumn Header="Price"
                 Binding="{Binding Price, StringFormat=C}" />
            </DataGrid.Columns>
        </DataGrid>
    </DockPanel>
 </Window>

The phrase ItemsSource="{Binding}" states that the content of the DataGrid is bound to a data source, which in this case will be inherited from the DataContext property of the parent Window.

Binding="{Binding Name}" specifies that the contents of the first column are bound to a Path named Name in the data source.

Similarly, Binding="{Binding Price, StringFormat=C}" specifies that the Path for the second column is Price (StringFormat=C merely specifies the default currency format).

The APL Code

The function Grid is shown below. 

     ∇ Grid;⎕USING;MySource;win
[1]    ⎕USING←'System'
[2]    winelist←⎕NS¨(⍴Wines)⍴⊂''
[3]    winelist.Name←Wines
[4]    winelist.Price←0.01×10000+?(⍴Wines)⍴10000
[5]
[6]    win←LoadXAML XAML
[7]    win.DataContext←2015⌶'winelist'
[8]    win.Show
     ∇

The global variable Wines contains a vector of character vectors, each of which is the name of a wine. Grid[2-4] creates winelist, a vector of namespaces, of the same length, each of which contains two variables c Name and Price.

Testing the Data Binding

      )LOAD wpfintro
      )CS DataBinding.DataGrid
      Grid

data binding datagrid1
Figure 2: data binding datagrid1

Let's round the prices to the nearest $5. 

 winelist.Price←5×⌊0.5+winelist.Price÷5

data binding datagrid2
Figure 3: data binding datagrid2