How to Bind a Command to a CheckBox

Question

I'm trying to bind the checkbox checkchange event to a command - MVVM Why doesn't this work? or do anything while the same works on button?

<CheckBox x:Name="radRefresh" IsChecked="{BindingREADY, Mode=TwoWay}" Command="{Binding Refresh_Command}" Content=" Refresh "  Margin="10,25,0,0"  />

<Button Command="{Binding Refresh_Command}" />

thanks

Solution 1

This will work...

<i:Interaction.Triggers> <i:EventTrigger EventName="Click"> <cmd:EventToCommand Command="{Binding Path=YourCommand,Mode=OneWay}" CommandParameter="{Binding IsChecked, ElementName=YourCheckBox}"></cmd:EventToCommand> </i:EventTrigger> </i:Interaction.Triggers>

where i is

xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"

Add namespace for cmd

    xmlns:cmd="clr-namespace:GalaSoft.MvvmLight.Command;assembly=GalaSoft.MvvmLight.Extras.WPF4"

This is one of the preferred ways for MVVM if you are utilizing the MVVMLight Framework.

Solution 2

You don't need to bind it to an event. All you need to do is bind IsChecked to a boolean dependency property, and do whatever logic you'd like on its setter.

Like this -

<CheckBox x:Name="radRefresh" IsChecked="{Binding IsChecked, Mode=TwoWay}" Content=" Refresh "  Margin="10,25,0,0"  />

This xaml should bind you to this property on the VM

  public bool IsChecked
  {
      get
      {
          return isChecked;
      }
      set
      {
          isChecked = value;
          NotifyPropertChanged("IsChecked");

          //Add any logic you'd like here
       }
   }

Solution 3

This is a simple situation:

1. Bind the CheckBox.IsChecked to a boolean value in your ViewModel.
2. In your viewmodel, subscribe to the property changed event and watch for the boolean value to change.

Done.

Comments

[Jan Kratochvil]

what is the cmd namespace, isn't it from the MVVM Light toolkit?

[Jan Kratochvil]

Thanks for the clarification. The thing is, not everybody is using MVVM Light (I prefer Prism) so calling it "the only preferred way" is a bit strong :-)

[Manvinder]

Hi Orchestraor, i like your answer, kindly clear my on couple of things.You said, i need to bind my property to a Dependency property, so first i have to create a dependency property in my VM? and do i need to set the Content="Refresh" property or it could do without refreshing it?

[Dror]

Hi Manav, Yes you would have to create a property just like I specified in the code. I call it a dependency property because it raises the NotifyPropertChanged event. that's why your ViewModel must implement the INotifyPropertChanged interface. You don't need to set any other property besides the "IsChecked" property, I only added them because they existed in Jon's question.

[Scott]

Some examples of how to do this without MVVM Light can be found here.