Question

I am using the silverlight 4 toolkit gridcontrol and I’m using auto generated columns. My boolean field is showing up as a tri-state checkbox (true, false, null).

public bool? Enabled { get; set; }

How to I force it to use only two states (true/false). Changing the field type is not an option at this time.

@Bala

[XAML]

<sdk:DataGrid Grid.Row="1" Grid.Column="1" x:Name="liveGrid" 
HorizontalAlignment="Center"
VerticalScrollBarVisibility="Hidden"  HorizontalContentAlignment="Center"
ItemsSource="{Binding MyDatasource}" AutoGenerateColumns="True" />

Just a thought: does a UIHint data annotation exist for this, maybe?

Possible Solution

Following @Rick I have a working solution:

[XAML]

<sdk:DataGrid Grid.Row="1" Grid.Column="1" x:Name="liveGrid" 
HorizontalAlignment="Center"
VerticalScrollBarVisibility="Hidden"  HorizontalContentAlignment="Center"
AutoGeneratingColumn="viewModel_AutoGeneratingColumn" 
ItemsSource="{Binding MyDatasource}" AutoGenerateColumns="True" />

[View]

 private void viewModel_AutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
    {
        if ("Enabled" == e.PropertyName)
        {
            DataGridCheckBoxColumn checkBox = e.Column as DataGridCheckBoxColumn;
            checkBox.IsThreeState = false;
        }
    }

Answer 1

You can continue to use auto-generated columns and customize those columns. Here is an article that describes how to customize auto-generated columns:

• How to: Customize Auto-Generated Columns in the DataGrid Control

The technique mainly consists of hooking the DataGrid.AutoGeneratingColumn event.

If you follow that procedure, all you need to do is find your column (e.g. by property name) and set IsThreeState to false:

• DataGridCheckBoxColumn.IsThreeState Property