How to prevent RadioButton unchecked once it is checked? - xaml

Question

I've got an enum like this:
public enum DLTypeEnum
{
Others = 1, People = 2, Company = 4,
}
I have a property in my ViewModel like this:
private DLTypeEnum _DLType;
public DLTypeEnum DLType
{
get { return _DLType; }
set { SetProperty(ref _DLType, value); }
}
Here is my xaml:
<WrapPanel Grid.Row="3" Grid.Column="1">
<WrapPanel.Resources>
<Converter:EnumToBoolConverter x:Key="EnumToBooleanConverter" />
</WrapPanel.Resources>
<RadioButton GroupName="DLType" IsChecked="{Binding Path=DLType,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged, Converter={StaticResource EnumToBooleanConverter}, ConverterParameter={x:Static dlAccount:DLTypeEnum.Others}}"/>
<RadioButton GroupName="DLType" IsChecked="{Binding Path=DLType,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged, Converter={StaticResource EnumToBooleanConverter}, ConverterParameter={x:Static dlAccount:DLTypeEnum.People}}"/>
<RadioButton GroupName="DLType" IsChecked="{Binding Path=DLType,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged, Converter={StaticResource EnumToBooleanConverter}, ConverterParameter={x:Static dlAccount:DLTypeEnum.Company}}"/>
</WrapPanel>
And this converter:
public class EnumToBoolConverter:IValueConverter
{
private int val;
public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
{
int intParam = (int)parameter;
val = (int)value;
return ((intParam & val) != 0);
}
public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)//bool to enum
{
val ^= (int)parameter;
return Enum.Parse(targetType, val.ToString());
}
}
Once the RadioButton is checked, I don't want it to be unchecked unless it select the other RadioButton (ie. one RadioButton must be selected all the time).

Answer 1

Try this code:
<WrapPanel Grid.Row="3" Grid.Column="1">
<WrapPanel.Resources>
<Converter:EnumToBoolConverter x:Key="EnumToBooleanConverter" />
</WrapPanel.Resources>
<RadioButton GroupName="DLType" IsChecked="{Binding Path=DLType,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged, Converter={StaticResource EnumToBooleanConverter}, ConverterParameter={x:Static dlAccount:DLTypeEnum.Others}}" Unchecked="RadioButton_Unchecked"/>
<RadioButton GroupName="DLType" IsChecked="{Binding Path=DLType,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged, Converter={StaticResource EnumToBooleanConverter}, ConverterParameter={x:Static dlAccount:DLTypeEnum.People}}" Unchecked="RadioButton_Unchecked"/>
<RadioButton GroupName="DLType" IsChecked="{Binding Path=DLType,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged, Converter={StaticResource EnumToBooleanConverter}, ConverterParameter={x:Static dlAccount:DLTypeEnum.Company}}" Unchecked="RadioButton_Unchecked"/>
</WrapPanel>
And Code behind:
private void RadioButton_Unchecked(object sender, RoutedEventArgs e)
{
if((_viewModel.DLss.CurrentItem as DL).DLType == 0)
((RadioButton)sender).IsChecked = true;
}