Simple WPF RadioButton Binding

Question

What is the simplest way to bind a group of 3 radiobuttons to a property of type int for values 1  2  or 3

User · Answer

This example might be seem a bit lengthy, but its intention should be quite clear.

It uses 3 Boolean properties in the ViewModel called, FlagForValue1, FlagForValue2 and FlagForValue3. Each of these 3 properties is backed by a single private field called _intValue.

The 3 Radio buttons of the view (xaml) are each bound to its corresponding Flag property in the view model. This means the radio button displaying "Value 1" is bound to the FlagForValue1 bool property in the view model and the other two accordingly.

When setting one of the properties in the view model (e.g. FlagForValue1), its important to also raise property changed events for the other two properties (e.g. FlagForValue2, and FlagForValue3) so the UI (WPF INotifyPropertyChanged infrastructure) can selected / deselect each radio button correctly.

    private int _intValue;

    public bool FlagForValue1
    {
        get
        {
            return (_intValue == 1) ? true : false;
        }
        set
        {
            _intValue = 1;
            RaisePropertyChanged("FlagForValue1");
            RaisePropertyChanged("FlagForValue2");
            RaisePropertyChanged("FlagForValue3");
        }
    }

    public bool FlagForValue2
    {
        get
        {
            return (_intValue == 2) ? true : false;
        }
        set
        {
            _intValue = 2;
            RaisePropertyChanged("FlagForValue1");
            RaisePropertyChanged("FlagForValue2");
            RaisePropertyChanged("FlagForValue3");
        }
    }

    public bool FlagForValue3
    {
        get
        {
            return (_intValue == 3) ? true : false;
        }
        set
        {
            _intValue = 3;
            RaisePropertyChanged("FlagForValue1");
            RaisePropertyChanged("FlagForValue2");
            RaisePropertyChanged("FlagForValue3");
        }
    }

The xaml looks like this:

                <RadioButton GroupName="Search" IsChecked="{Binding Path=FlagForValue1, Mode=TwoWay}"
                             >Value 1</RadioButton>

                <RadioButton GroupName="Search" IsChecked="{Binding Path=FlagForValue2, Mode=TwoWay}"
                             >Value 2</RadioButton>

                <RadioButton GroupName="Search" IsChecked="{Binding Path=FlagForValue3, Mode=TwoWay}"
                             >Value 3</RadioButton>

User · Answer

Sometimes it is possible to solve it in the model like this  Suppose you have 3 boolean properties OptionA  OptionB  OptionC   XAML    lt RadioButton IsChecked   Binding OptionA    gt   lt RadioButton IsChecked   Binding OptionB    gt   lt RadioButton IsChecked   Binding OptionC    gt    CODE   private bool  optionA  public bool OptionA       get   return  optionA        set                optionA   value          if   optionA                          this OptionB  false               this OptionC   false                     private bool  optionB  public bool OptionB       get   return  optionB        set                optionB   value          if   optionB                         this OptionA  false              this OptionC   false                     private bool  optionC  public bool OptionC       get   return  optionC        set                optionC   value          if   optionC                         this OptionA  false              this OptionB   false                      You get the idea  Not the cleanest thing  but easy

User · Answer

I ve come up with solution using Binding DoNothing returned from converter which doesn t break two-way binding   public class EnumToCheckedConverter   IValueConverter       public Type Type   get  set         public object Convert object value  Type targetType  object parameter  CultureInfo culture                if  value    null  amp  amp  value GetType      Type                        try                               var parameterFlag   Enum Parse Type  parameter as string                    if  Equals parameterFlag  value                                         return true                                              catch  ArgumentNullException                                return false                            catch  ArgumentException                                throw new NotSupportedException                               return false                    else if  value    null                        return false                     throw new NotSupportedException               public object ConvertBack object value  Type targetType  object parameter  CultureInfo culture                if  value    null  amp  amp  value is bool check                        if  check                                try                                       return Enum Parse Type  parameter as string                                     catch ArgumentNullException                                        return Binding DoNothing                                    catch ArgumentException                                        return Binding DoNothing                                               return Binding DoNothing                     throw new NotSupportedException              Usage    lt converters EnumToCheckedConverter x Key  SourceConverter  Type   x Type monitor VariableValueSource     gt    Radio button bindings    lt RadioButton GroupName  ValueSource                IsChecked   Binding Source  Converter  StaticResource SourceConverter   ConverterParameter Function   gt Function lt  RadioButton gt

User · Answer

I know it s way way overdue  but I have an alternative solution  which is lighter and simpler  Derive a class from System Windows Controls RadioButton and declare two dependency properties RadioValue and  RadioBinding  Then in the class code  override OnChecked and set the RadioBinding property value to that of the RadioValue property value  In the other direction  trap changes to the RadioBinding property using a callback  and if the new value is equal to the value of the RadioValue property  set its IsChecked property to true   Here s the code   public class MyRadioButton   RadioButton       public object RadioValue               get   return  object GetValue RadioValueProperty             set   SetValue RadioValueProperty  value                   Using a DependencyProperty as the backing store for RadioValue         This enables animation  styling  binding  etc        public static readonly DependencyProperty RadioValueProperty           DependencyProperty Register               RadioValue                typeof object                typeof MyRadioButton                new UIPropertyMetadata null         public object RadioBinding               get   return  object GetValue RadioBindingProperty             set   SetValue RadioBindingProperty  value                   Using a DependencyProperty as the backing store for RadioBinding         This enables animation  styling  binding  etc        public static readonly DependencyProperty RadioBindingProperty           DependencyProperty Register               RadioBinding                typeof object                typeof MyRadioButton                new FrameworkPropertyMetadata                  null                   FrameworkPropertyMetadataOptions BindsTwoWayByDefault                   OnRadioBindingChanged         private static void OnRadioBindingChanged          DependencyObject d          DependencyPropertyChangedEventArgs e                MyRadioButton rb    MyRadioButton d          if  rb RadioValue Equals e NewValue               rb SetCurrentValue RadioButton IsCheckedProperty  true              protected override void OnChecked RoutedEventArgs e                base OnChecked e           SetCurrentValue RadioBindingProperty  RadioValue             XAML usage    lt my MyRadioButton GroupName  grp1  Content  Value 1      RadioValue  val1  RadioBinding   Binding SelectedValue    gt   lt my MyRadioButton GroupName  grp1  Content  Value 2      RadioValue  val2  RadioBinding   Binding SelectedValue    gt   lt my MyRadioButton GroupName  grp1  Content  Value 3      RadioValue  val3  RadioBinding   Binding SelectedValue    gt   lt my MyRadioButton GroupName  grp1  Content  Value 4      RadioValue  val4  RadioBinding   Binding SelectedValue    gt    Hope someone finds this useful after all this time

User · Answer

I created an attached property based on Aviad s Answer which doesn t require creating a new class  public static class RadioButtonHelper        AttachedPropertyBrowsableForType typeof RadioButton        public static object GetRadioValue DependencyObject obj    gt  obj GetValue RadioValueProperty       public static void SetRadioValue DependencyObject obj  object value    gt  obj SetValue RadioValueProperty  value       public static readonly DependencyProperty RadioValueProperty           DependencyProperty RegisterAttached  RadioValue   typeof object   typeof RadioButtonHelper   new PropertyMetadata new PropertyChangedCallback OnRadioValueChanged          private static void OnRadioValueChanged DependencyObject d  DependencyPropertyChangedEventArgs e                if  d is RadioButton rb                        rb Checked -  OnChecked              rb Checked    OnChecked                       public static void OnChecked object sender  RoutedEventArgs e                if  sender is RadioButton rb                        rb SetCurrentValue RadioBindingProperty  rb GetValue RadioValueProperty                          AttachedPropertyBrowsableForType typeof RadioButton        public static object GetRadioBinding DependencyObject obj    gt  obj GetValue RadioBindingProperty       public static void SetRadioBinding DependencyObject obj  object value    gt  obj SetValue RadioBindingProperty  value        public static readonly DependencyProperty RadioBindingProperty           DependencyProperty RegisterAttached  RadioBinding   typeof object   typeof RadioButtonHelper   new FrameworkPropertyMetadata null  FrameworkPropertyMetadataOptions BindsTwoWayByDefault  new PropertyChangedCallback OnRadioBindingChanged          private static void OnRadioBindingChanged DependencyObject d  DependencyPropertyChangedEventArgs e                if  d is RadioButton rb  amp  amp  rb GetValue RadioValueProperty  Equals e NewValue                         rb SetCurrentValue RadioButton IsCheckedProperty  true                       usage     lt RadioButton GroupName  grp1  Content  Value 1      helpers RadioButtonHelper RadioValue  val1  helpers RadioButtonHelper RadioBinding   Binding SelectedValue    gt   lt RadioButton GroupName  grp1  Content  Value 2      helpers RadioButtonHelper RadioValue  val2  helpers RadioButtonHelper RadioBinding   Binding SelectedValue    gt   lt RadioButton GroupName  grp1  Content  Value 3      helpers RadioButtonHelper RadioValue  val3  helpers RadioButtonHelper RadioBinding   Binding SelectedValue    gt   lt RadioButton GroupName  grp1  Content  Value 4      helpers RadioButtonHelper RadioValue  val4  helpers RadioButtonHelper RadioBinding   Binding SelectedValue    gt

User · Answer

I am very suprised nobody came up with this kind of solution to bind it against bool array  It might not be the cleanest  but it can be used very easily    private bool    modeArray   new bool     true  false  false   public bool   ModeArray       get   return  modeArray       public int SelectedMode       get   return Array IndexOf  modeArray  true         in XAML    lt RadioButton GroupName  Mode  IsChecked   Binding Path ModeArray 0   Mode TwoWay    gt   lt RadioButton GroupName  Mode  IsChecked   Binding Path ModeArray 1   Mode TwoWay    gt   lt RadioButton GroupName  Mode  IsChecked   Binding Path ModeArray 2   Mode TwoWay    gt    NOTE  you dont need two-way binding if you dont want to one checked by default  TwoWay binding is the biggest cons of this solution   Pros    No need for code behind No need for extra class  IValue Converter  No Need for extra enums doesnt require bizzare binding straightforward and easy to understand doesnt violate MVVM  heh  at least I hope so

User · Answer

Actually  using the converter like that breaks two-way binding  plus as I said above  you can t use that with enumerations either   The better way to do this is with a simple style against a ListBox  like this   Note  Contrary to what DrWPF com stated in their example  do not put the ContentPresenter inside the RadioButton or else if you add an item with content such as a button or something else  you will not be able to set focus or interact with it   This technique solves that   Also  you need to handle the graying of the text as well as removing of margins on labels or else it will not render correctly   This style handles both for you as well    lt Style x Key  RadioButtonListItem  TargetType   x Type ListBoxItem    gt        lt Setter Property  Template  gt           lt Setter Value gt                lt ControlTemplate TargetType  ListBoxItem  gt                    lt DockPanel LastChildFill  True  Background   TemplateBinding Background   HorizontalAlignment  Stretch  VerticalAlignment  Center   gt                        lt RadioButton IsChecked   TemplateBinding IsSelected   Focusable  False  IsHitTestVisible  False  VerticalAlignment  Center  Margin  0 0 4 0    gt                        lt ContentPresenter                         Content                 TemplateBinding ContentControl Content                           ContentTemplate         TemplateBinding ContentControl ContentTemplate                           ContentStringFormat     TemplateBinding ContentControl ContentStringFormat                           HorizontalAlignment     TemplateBinding Control HorizontalContentAlignment                           VerticalAlignment       TemplateBinding Control VerticalContentAlignment                           SnapsToDevicePixels     TemplateBinding UIElement SnapsToDevicePixels     gt                    lt  DockPanel gt                lt  ControlTemplate gt            lt  Setter Value gt        lt  Setter gt    lt  Style gt    lt Style x Key  RadioButtonList  TargetType  ListBox  gt        lt Style Resources gt           lt Style TargetType  Label  gt               lt Setter Property  Padding  Value  0    gt           lt  Style gt       lt  Style Resources gt        lt Setter Property  BorderThickness  Value  0    gt       lt Setter Property  Background       Value  Transparent    gt        lt Setter Property  ItemContainerStyle  Value   StaticResource RadioButtonListItem     gt        lt Setter Property  Control Template  gt           lt Setter Value gt               lt ControlTemplate TargetType   x Type ListBox   gt                   lt ItemsPresenter SnapsToDevicePixels   TemplateBinding UIElement SnapsToDevicePixels     gt               lt  ControlTemplate gt           lt  Setter Value gt       lt  Setter gt        lt Style Triggers gt           lt Trigger Property  IsEnabled  Value  False  gt               lt Setter Property  TextBlock Foreground  Value   DynamicResource  x Static SystemColors GrayTextBrushKey      gt           lt  Trigger gt       lt  Style Triggers gt    lt  Style gt    lt Style x Key  HorizontalRadioButtonList  BasedOn   StaticResource RadioButtonList   TargetType  ListBox  gt       lt Setter Property  ItemsPanel  gt           lt Setter Value gt               lt ItemsPanelTemplate gt                   lt VirtualizingStackPanel Background  Transparent  Orientation  Horizontal    gt               lt  ItemsPanelTemplate gt           lt  Setter Value gt       lt  Setter gt   lt  Style gt    You now have the look and feel of radio buttons  but you can do two-way binding  and you can use an enumeration   Here s how      lt ListBox Style   StaticResource RadioButtonList       SelectedValue   Binding SomeVal       SelectedValuePath  Tag  gt        lt ListBoxItem Tag   x Static l MyEnum SomeOption        gt Some option lt  ListBoxItem gt       lt ListBoxItem Tag   x Static l MyEnum SomeOtherOption   gt Some other option lt  ListBoxItem gt       lt ListBoxItem Tag   x Static l MyEnum YetAnother        gt Yet another option lt  ListBoxItem gt    lt  ListBox gt    Also  since we explicitly separated out the style that tragets the ListBoxItem rather than putting it inline  again as the other examples have shown  you can now create a new style off of it to customize things on a per-item basis such as spacing   This will not work if you simply try to target ListBoxItem as the keyed style overrides generic control targets    Here s an example of putting a margin of 6 above and below each item   Note how you have to explicitly apply the style via the ItemContainerStyle property and not simply targeting ListBoxItem in the ListBox s resource section for the reason stated above     lt Window Resources gt       lt Style x Key  SpacedRadioButtonListItem  TargetType  ListBoxItem  BasedOn   StaticResource RadioButtonListItem   gt           lt Setter Property  Margin  Value  0 6    gt       lt  Style gt   lt  Window Resources gt    lt ListBox Style   StaticResource RadioButtonList       ItemContainerStyle   StaticResource SpacedRadioButtonListItem       SelectedValue   Binding SomeVal       SelectedValuePath  Tag  gt        lt ListBoxItem Tag   x Static l MyEnum SomeOption        gt Some option lt  ListBoxItem gt       lt ListBoxItem Tag   x Static l MyEnum SomeOtherOption   gt Some other option lt  ListBoxItem gt       lt ListBoxItem Tag   x Static l MyEnum YetAnother        gt Ter another option lt  ListBoxItem gt    lt  ListBox gt

User · Answer

I came up with a simple solution   I have a model cs class with   private int  isSuccess  public int IsSuccess   get   return  isSuccess    set    isSuccess   value        I have Window1 xaml cs file with DataContext set to model cs  The xaml contains the radiobuttons    lt RadioButton IsChecked   Binding Path IsSuccess  Converter  StaticResource radioBoolToIntConverter   ConverterParameter 1   Content  one    gt   lt RadioButton IsChecked   Binding Path IsSuccess  Converter  StaticResource radioBoolToIntConverter   ConverterParameter 2   Content  two    gt   lt RadioButton IsChecked   Binding Path IsSuccess  Converter  StaticResource radioBoolToIntConverter   ConverterParameter 3   Content  three    gt    Here is my converter   public class RadioBoolToIntConverter   IValueConverter       public object Convert object value  Type targetType  object parameter  CultureInfo culture                int integer    int value          if  integer  int Parse parameter ToString                 return true          else             return false             public object ConvertBack object value  Type targetType  object parameter  CultureInfo culture                return parameter            And of course  in Window1 s resources    lt Window Resources gt       lt local RadioBoolToIntConverter x Key  radioBoolToIntConverter    gt   lt  Window Resources gt

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