SelectAll In Datagrid - wpf

Question

I found a nice solution for SelectAll Checkboxes in a datagrid using XAML only:
<DataGrid x:Name="TestGrid" Tag="false">
<DataGrid.Resources>
<DataTemplate x:Key="HeaderCheckbox">
<CheckBox Name="SelectAll" IsChecked="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=DataGrid}, Path=Tag, Mode=TwoWay}" />
</DataTemplate>
<DataTemplate x:Key="ItemCheckbox">
<CheckBox IsChecked="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=DataGrid}, Path=Tag, Mode=OneWay}" />
</DataTemplate>
</DataGrid.Resources>
<DataGrid.Columns>
<DataGridTemplateColumn HeaderTemplate="{StaticResource HeaderCheckbox}" CellTemplate="{StaticResource ItemCheckbox}" />
<DataGridTextColumn Binding="{Binding FirstName}" />
</DataGrid.Columns>
</DataGrid>
Source: Complete XAML Solution For SelectAll In Datagrid
But it's my question... In above example, the ItemCheckbox is bound to tag property of Datagrid, then how do I to bind the ItemCheckbox to my data field inclusive?

Answer 1

Easiest solution I can see it to use properties in your view model instead of Tag. First in class that holds items create SelectAll property that will update accordingly all items when changed:
public class MyItemCollection : INotifyPropertyChanged
{
private readonly ObservableCollection<MyItem> _items;
public ICollection<MyItem> Items { get { return _items; } }
private bool _selectAll;
public bool SelectAll
{
get { return _selectAll; }
set
{
if (_selectAll != value)
{
_selectAll = value;
OnPropertyChanged("SelectAll");
foreach (var item in _items) item.IsSelected = value;
}
}
}
}
Then add IsSelected property to your item. It will be updated either by SelectAll property or CheckBox in DataGrid
public class MyItem : INotifyPropertyChanged
{
private bool _isSelected;
public bool IsSelected
{
get { return _isSelected; }
set
{
if (_isSelected != value)
{
_isSelected = value;
OnPropertyChanged("IsSelected");
}
}
}
}
and then update your binding to point to new properties:
<DataGrid x:Name="TestGrid" ItemsSource="{Binding Items}">
<DataGrid.Resources>
<DataTemplate x:Key="HeaderCheckbox">
<CheckBox Name="SelectAll" IsChecked="{Binding RelativeSource={RelativeSource AncestorType=DataGrid}, Path=DataContext.SelectAll}" />
</DataTemplate>
<DataTemplate x:Key="ItemCheckbox">
<CheckBox IsChecked="{Binding Path=IsSelected}" />
</DataTemplate>
</DataGrid.Resources>
</DataGrid>