C# – WPF Check box: Check changed handling

ccheckboxwpf

In WPF data binding, I can bind the IsChecked property to some data, e.g. user setting, but I need to handle "CheckChanged" event, I know I can seperately handle Checked, Unchecked event, but is there any way to get notified when this value is changed?

<CheckBox Content="Case Sensitive" IsChecked="{Binding bSearchCaseSensitive,
          Source={x:Static Properties:Settings.Default}}" />

Note: I don't care if it is checked or unchecked. I just want to be notified when it is changed.

Best Answer

That you can handle the checked and unchecked events seperately doesn't mean you have to. If you don't want to follow the MVVM pattern you can simply attach the same handler to both events and you have your change signal:

<CheckBox Checked="CheckBoxChanged" Unchecked="CheckBoxChanged"/>

and in Code-behind;

private void CheckBoxChanged(object sender, RoutedEventArgs e)
{
  MessageBox.Show("Eureka, it changed!");
}

Please note that WPF strongly encourages the MVVM pattern utilizing INotifyPropertyChanged and/or DependencyProperties for a reason. This is something that works, not something I would like to encourage as good programming habit.

Related Solutions

Javascript – How to check whether a checkbox is checked in jQuery

How do I successfully query the checked property?

The checked property of a checkbox DOM element will give you the checked state of the element.

Given your existing code, you could therefore do this:

if(document.getElementById('isAgeSelected').checked) {
    $("#txtAge").show();
} else {
    $("#txtAge").hide();
}

However, there's a much prettier way to do this, using toggle:

$('#isAgeSelected').click(function() {
    $("#txtAge").toggle(this.checked);
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="checkbox" id="isAgeSelected"/>
<div id="txtAge" style="display:none">Age is something</div>

WPF checkbox IsChecked property does not change according to binding value

The problem you're having here is that the CheckBox doesn't know when the value of dataType1.IsChecked changes. To fix that, change your dataType1 to:

class dataType1 : INotifyPropertyChanged
{ 
    public string ItemName { get; set; }

    private bool isChecked;
    public bool IsChecked 
    {
        get { return isChecked; }
        set 
        {
            if (isChecked != value)
            {
                isChecked = value;
                if (PropertyChanged != null)
                {
                    PropertyChanged(this, new PropertyChangedEventArgs("IsChecked"));
                }
            }
        }
    }
    public event PropertyChangedEventHandler PropertyChanged;
}

So now, when the property value is changed it will notify the binding that it needs to update by raising the PropertyChanged event.

Also, there are easier ways to do this that avoid you having to write as much boiler-plate code. I use BindableObject from Josh Smith.

Best Answer

Related Solutions

Javascript – How to check whether a checkbox is checked in jQuery

WPF checkbox IsChecked property does not change according to binding value

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