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Editorial Team
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Asked: 2026-06-04T03:48:20+00:00

I have an class, let’s refer to it as SomeClass. SomeClass implements INotifyPropertyChanged and

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I have an class, let’s refer to it as SomeClass. SomeClass implements INotifyPropertyChanged and this is coded as follows:

public class SomeClass
{
.
.
.
private bool _isDirty;

public bool IsDirty
{
    get { return this._isDirty; }
    set
    {
    this._isDirty = value;
    this.NotifyPropertyChanged("IsDirty");
    }
}

public event PropertyChangedEventHandler PropertyChanged;

public void NotifyPropertyChanged(string propertyName)
{
    if (this.PropertyChanged != null)
    {
    this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
    }
}
}

I have a form that uses an instance of SomeClass, called instanceOfSomeClass

This property all fires correctly but onto the main issue which is where I have a Save button bound to that property viz.

<Button Content="Save" Height="23" Name="btnSave" IsEnabled="{Binding Path=IsDirty}" Width="60" Margin="10, 10" HorizontalAlignment="Right" Click="btnSave_Click" />

A combo box SelectionChanged event is supposed to change that property is defined as follows:

<ComboBox Name="cboListOfUsers" ItemsSource="{Binding}" SelectionChanged="cboSomeCombo_SelectionChanged"/>

(I have removed parts of the combo box definition that are not pertinent to the question such as styles etc)

Critically the DataContext of the combo box is not set to the instanceOfSomeClass, rather a List of a custom class.

The SelectionChanged event fires and I have code that looks like this:

instanceOfSomeClass.IsDirty = true;
instanceOfSomeClass.User = (ApplicationUser) cboSomeCombo.SelectedItem;

This runs and although it does change the property and raise the appropriate notification it doesn’t enable the command button. I surmise that this is because the DataContext for the combo is different to the DataContext for the command button

I’ve tried changing the DataContext in the SelectionChanged event but this just results in nothing being selected in the combo (the Save button is enabled though!)

Any help would be greatly appreciated

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1 Answer

  1. Editorial Team

    I surmise that this is because the DataContext for the combo is
    different to the DataContext for the command button

    no i don’t think so. You could try that by not binding the ItemsSource directly to the DataContext instead using a member on the datacontext or using RelativeSource, ElementName, directly specifying the source or another binding syntax. I greatly suggest to use a collection from a property and not set the collection as the datacontext (personally i think thats really bad style, {Binding} should only be used very rarely and i use it only when ContentControls are involved).

    Check the Datacontext on the button, use snoop for that it helps greatly by finding bugs like these. Make sure the property is REALLY raised, i can’t count how many times we didn’t step in the actual NotifyPropertyChanged where the bug was.

    Make sure your button doesn’t use a command sowhere because commands change the IsEnabled property in some ways.

    Make sure nobody is overwriting the IsEnabled property, like Triggers, Animations etc.

    Check the output for binding errors or warnings, enable them if you use vs10.

    I will update my answer if you can provide more info, was just to much for a comment.

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