WPF checkbox binding

Question

While it is trivial to store a checkbox s checked state in a variable using the checkbox s Click event  how would I do it via databinding   All the examples I have found have the UI updated from some datasource  or bind one control to another  I want to update a member variable when the checkbox is clicked   TIA for any pointers

User · Answer

Hello this is my first time posting so please be patient: my answer was to create a simple property:

public bool Checked { get; set; }

Then to set the data context of the Checkbox (called cb1):

cb1.DataContext = this;

Then to bind the IsChecked proerty of it in the xaml

IsChecked="{Binding Checked}"

The code is like this:

XAML

<CheckBox x:Name="cb1"
          HorizontalAlignment="Left"
          Margin="439,81,0,0"
          VerticalAlignment="Top"
          Height="35" Width="96"
          IsChecked="{Binding Checked}"/>

Code behind

public partial class MainWindow : Window
{
    public bool Checked { get; set; }

    public MainWindow()
    {
        InitializeComponent();

        cb1.DataContext = this;
    }

    private void myyButton_Click(object sender, RoutedEventArgs e)
    {
        MessageBox.Show(Checked.ToString());
    }
}

User · Answer

You need a dependency property for this   public BindingList lt User gt  Users       get   return  BindingList lt User gt  GetValue UsersProperty         set   SetValue UsersProperty  value        public static readonly DependencyProperty UsersProperty       DependencyProperty Register  Users   typeof BindingList lt User gt           typeof OptionsDialog      Once that is done  you bind the checkbox to the dependency property    lt CheckBox x Name  myCheckBox            IsChecked   Binding ElementName window1  Path CheckBoxIsChecked     gt    For that to work you have to name your Window or UserControl in its openning tag  and use that name in the ElementName parameter   With this code  whenever you change the property on the code side  you will change the textbox  Also  whenever you check uncheck the textbox  the Dependency Property will change too   EDIT   An easy way to create a dependency property is typing the snippet propdp  which will give you the general code for Dependency Properties   All the code   XAML    lt Window x Class  StackOverflowTests Window1      xmlns  http   schemas microsoft com winfx 2006 xaml presentation      xmlns x  http   schemas microsoft com winfx 2006 xaml      Title  Window1  x Name  window1  Height  300  Width  300  gt       lt Grid gt           lt StackPanel Orientation  Vertical  gt               lt CheckBox Margin  10                        x Name  myCheckBox                        IsChecked   Binding ElementName window1  Path IsCheckBoxChecked   gt                  Bound CheckBox              lt  CheckBox gt               lt Label Content   Binding ElementName window1  Path IsCheckBoxChecked                      ContentStringFormat  Is checkbox checked   0     gt           lt  StackPanel gt       lt  Grid gt   lt  Window gt    C    using System Windows   namespace StackOverflowTests            lt summary gt          Interaction logic for Window1 xaml          lt  summary gt      public partial class Window1   Window               public bool IsCheckBoxChecked                      get   return  bool GetValue IsCheckBoxCheckedProperty                set   SetValue IsCheckBoxCheckedProperty  value                           Using a DependencyProperty as the backing store for             IsCheckBoxChecked   This enables animation  styling  binding  etc            public static readonly DependencyProperty IsCheckBoxCheckedProperty               DependencyProperty Register  IsCheckBoxChecked   typeof bool                typeof Window1   new UIPropertyMetadata false             public Window1                                      InitializeComponent                        Notice how the only code behind is the Dependency Property  Both the label and the checkbox are bound to it  If the checkbox changes  the label changes too

User · Answer

Should be easier than that   Just use    lt Checkbox IsChecked   Binding Path myVar  UpdateSourceTrigger PropertyChanged     gt

User · Answer

This works for me  essential code only included  fill more for your needs    In XAML a user control is defined     lt UserControl x Class  Mockup TestTab         gt       lt  -- a checkbox somewhere within the control -- gt       lt  -- IsChecked is bound to Property C1 of the DataContext -- gt       lt CheckBox Content  CheckBox 1  IsChecked   Binding C1  Mode TwoWay     gt   lt  UserControl gt    In code behind for UserControl  public partial class TestTab   UserControl       public TestTab                 InitializeComponent        the standard bit         then we set the DataContex of TestTab Control to a MyViewModel object        this MyViewModel object becomes the DataContext for all controls             within TestTab     including our CheckBox          DataContext   new MyViewModel                   Somewhere in solution class MyViewModel is defined  public class MyViewModel   INotifyPropertyChanged        public event PropertyChangedEventHandler PropertyChanged      private bool m c1   true       public bool C1           get   return m c1            set               if  m c1    value                    m c1   value                  if  PropertyChanged    null                      PropertyChanged this  new PropertyChangedEventArgs  C1

User · Answer

You must make your binding bidirectional     lt checkbox IsChecked   Binding Path MyProperty  Mode TwoWay    gt

User · Answer

if you have the property  MyProperty  on your data-class  then you bind the IsChecked like this       the converter is optional  but sometimes you need that    lt Window Resources gt   lt local MyBoolConverter x Key  MyBoolConverterKey   gt   lt  Window Resources gt   lt checkbox IsChecked   Binding Path MyProperty  Converter  StaticResource MyBoolConverterKey     gt

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