Bind List of strings to UI as Checkboxes? - wpf

Question

I have a List<String> in a custom user control. Whenever the List<String> is modified, I want the custom user control to have checkboxes for every item in the List<String>. My original idea (being used to Java) was to just add the checkboxes and remove them directly.
But... I know C# can do better than that. Is there some way I can "bind" the strings to the UI so they show up as checkboxes? (or any other method that works?)

Answer 1

You can do that easily by binding an ItemsControl to the list of strings:
<ItemsControl ItemsSource="{Binding Strings}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<CheckBox Content="{Binding}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
However that's not very useful, because you have no easy way to access the state of the CheckBox... A better option would be to wrap the string in a class that also exposes a bool property:
public class CheckableItem<T> : INotifyPropertyChanged
{
public CheckableItem(T value)
{
_value = value;
}
private T _value;
public T Value
{
get { return _value; }
set
{
_value = value;
OnPropertyChanged("Value");
}
}
private bool _isChecked;
public bool IsChecked
{
get { return _isChecked; }
set
{
_isChecked = value;
OnPropertyChanged("IsChecked");
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
var handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
You can then expose a list of CheckableItem<string> instead of a list of strings, and change the XAML as follows:
<ItemsControl ItemsSource="{Binding Items}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<CheckBox Content="{Binding Value}" IsChecked="{Binding IsChecked}" />
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
If you need to test if the CheckBox is checked, just test the IsChecked property in the CheckableItem<T> class.
If you need the CheckBox to have 3 states (checked/unchecked/indeterminate), just declare IsChecked as bool? instead of bool.