SelectionChanged isn't firing when user changes combobox in WPF

Question

So my selectionChanged event isn't firing when a user changes it but fires if I change it in code.

I'm using the selectionchanged to get a selection from a combobox to fill another combobox.

<!--1st list -->
<ComboBox ItemsSource="{Binding djurKatList}" SelectedItem="{Binding SelectedDjurKat}" SelectionChanged="listKat_SelectionChanged" x:Name="listKat" HorizontalAlignment="Left" Margin="98,118,0,0" VerticalAlignment="Top" Width="120"/>

<!--2nd list that's filled after something is selected in 1st list-->
<ComboBox ItemsSource="{Binding djurArtList}" SelectedItem="{Binding SelectedDjurArt}" x:Name="listDjur" HorizontalAlignment="Left" Margin="98,154,0,0" VerticalAlignment="Top" Width="120"/>

In code behind this fills the 2nd combobox and isn't executing when I change the 1st combobox:

private void listKat_SelectionChanged(object sender, SelectionChangedEventArgs e)
{            
    fyllDjurArtLista(hanterare, typeof(Daggdjur));
}

When I change the selection in code, selectionChanged fires, here below I change my selected comboboxitem, the event is fired and 2nd combobox gets filled.

var listItem = new ComboBoxItem { Content = "Välj kategori" };
SelectedDjurKat = listItem;

Possible duplicate of could the SelectionChanged event in WPF be handled only for user interaction? — Arash

Peter Ožbot Peter Ožbot · Accepted Answer · 2015-01-31T18:51:35

Here is simple example and it works.

/// <summary>
/// Interaction logic for MainWindow.xaml
/// </summary>
public partial class MainWindow : Window {
    public MainWindow() {
        InitializeComponent();

        VM v = new VM();
        v.djurKatList = new List<string>();
        v.djurKatList.Add("1");
        v.djurKatList.Add("2");
        v.djurKatList.Add("3");
        v.djurKatList.Add("4");
        v.djurKatList.Add("5");

        DataContext = v;
    }

    private void listKat_SelectionChanged(object sender, SelectionChangedEventArgs e) {
       // fyllDjurArtLista(hanterare, typeof(Daggdjur));
    }
}

public class VM {
    public List<string> djurKatList { get; set; }
    public string SelectedDjurKat { get; set; }
}

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <StackPanel>
        <!--1st list -->
        <ComboBox ItemsSource="{Binding djurKatList}" SelectedItem="{Binding SelectedDjurKat}" SelectionChanged="listKat_SelectionChanged"
                  x:Name="listKat" HorizontalAlignment="Left" Margin="98,118,0,0" VerticalAlignment="Top" Width="120"/>

        <!--2nd list that's filled after something is selected in 1st list-->
        <ComboBox ItemsSource="{Binding djurArtList}" SelectedItem="{Binding SelectedDjurArt}" x:Name="listDjur" HorizontalAlignment="Left"
                  Margin="98,154,0,0" VerticalAlignment="Top" Width="120"/>
    </StackPanel>
</Grid>

The SelectionChanged is fired. But if the problem is that the other combo box is not filled then you need to use INotifyPropertyChanged as suggested. You need to call PropertyChanged for the property djurArtList.

SelectionChanged isn't firing when user changes combobox in WPF

1 Answers