Question

I have a WPF expander with a databound item. Im trying to set a bool flag in the databound item in code behind to have teh expander collapse when the bool is set. I set the bool in the databound object but the expander is not reflecting the change and collapsing. Please let me know if you need anymore information.

Had a closer look and it appears im not implementing InotifyPropertyChanged. Reading up on it now but answers specific to my problem would be appreciated.

Here is my XAML:

<Expander Header="{Binding SubSection.SubSectionName}" Expanded="Expander_Expanded" Collapsed="Expander_Collapsed" IsExpanded="{Binding SubSection.Expanded}">

Here is my code behind:

loopSubVM.SubSection.Expanded = false;

Expanded definition:

public class SubSectionViewModel
    {
        ObservableCollection<MaterialViewModel> _materials = new ObservableCollection<MaterialViewModel>();
        ObservableCollection<SubSectionViewModel> _subSections = new ObservableCollection<SubSectionViewModel>();
        SubSection _subSection;
        SectionViewModel _sectionVM;

public class SubSection
    {
        string _subSectionName;
        object _subSectionValue;
        List<GX3MaterialInterface.GX3MaterialInterface.MATERIAL_TYPE> _sectionTypes;
        int _currentTypePosition;
        List<List<object>> _paramterList;
        bool _expanded = false;

Answer 1

Make sure that setting Expanded raises the PropertyChanged event.