Combobox in settingsflyout does not show selected values when opening it again

Question

This seemed so simple but has turned into a nightmare for me. Everything works great, i can select a value and it's reported back to the view model.

Problem: User opens the settings flyout and selects a value. User exits the flyout. User reopens the settings flyout and there is no selected value in the combobox. The value exists in the view model though.

Scenario: Combobox in a Settingsflyout.

<ComboBox x:Name="defaultComboBox" SelectedItem="{Binding UserSettings.DefaultAccount, Mode=TwoWay}"  ItemsSource="{Binding UserAccounts}" DisplayMemberPath="CustomName">

<interactivity:Interaction.Behaviors>
            <core:EventTriggerBehavior EventName="Loaded">
                <core:InvokeCommandAction Command="{Binding UserAccountComboboxLoadedCommand}" CommandParameter="{Binding ElementName=defaultAccountComboBox}"/>
            </core:EventTriggerBehavior>
            </interactivity:Interaction.Behaviors>
</ComboBox>

ViewModelCode:

    public void Open(object parameter, Action successAction)
    {
        logger.LogProgress("Opened UserSettingsFlyoutView.");
        UserSettings.DefaultAccount =  UserAccounts.FirstOrDefault(u => u.AccountID.ToString().Equals(userSettings.DefaultAccountGuid,StringComparison.CurrentCultureIgnoreCase));
    }

    public CrossThreadObservableCollection<UserAccount> UserAccounts
    {
        get
        {
            try
            {
                return dbContext.RetrieveAllUserAccounts();
            }
            catch(Exception e)
            {
                logger.LogError("Error happened when retrieving user-accounts from secure data store Error: " + e.Message, e.ToString());
                return new CrossThreadObservableCollection<UserAccount>();
            }
        }
    } 

    private IProvideUserSetting userSettings;

    public IProvideUserSetting UserSettings
    {
        get { return userSettings; }
        set { userSettings = value; OnPropertyChanged("UserSettings"); }
    }

UserSettings class:

 private string defaultAccountGuid;
    [DataMember]
    public string DefaultAccountGuid
    {
        get { return defaultAccountGuid; }
        set { defaultAccountGuid = value; OnPropertyChanged("DefaultAccountGuid"); }
    }

    private UserAccount defaultAccount;
    [IgnoreDataMember]
    public UserAccount DefaultAccount
    {
        get { return defaultAccount; }
        set { 
            defaultAccount = value;
            if (defaultAccount != null)
                DefaultAccountGuid = defaultAccount.AccountID.ToString();
            OnPropertyChanged("DefaultAccount"); }
    }

Answer 1

I tried a version of the code and could not reproduce the issue. Could you provide more code? Is there something else setting the selected item?

Anyway, the type of item in the ItemsSource is different than the type of item for selected item. I would try changing the selected item binding to the same class in the items source.

For example, instead of the viewmodel property UserSettings, make that object type UserAccount.

Something like

    private UserAccount _selectedUserAccount { get; set; }

    public UserAccount SelectedUserAccount
    {
        get { return _selectedUserAccount; }
        set
        {
            if (_selectedUserAccount != value)
            {
                _selectedUserAccount = value;
                OnPropertyChanged("SelectedUserAccount");
            }
        }
    }

Edit:

You can add a loaded event handler to your combobox, then locate the viewmodel from the code behind and set the selected item property.

    private void ComboBox_Loaded(object sender, RoutedEventArgs e)
    {
        ComboBox comboBox = sender as ComboBox;
        comboBox.SelectedItem =
            _viewModel.UserAccounts.Where(x => x.UserAccountString ==  _viewModel.SelectedUserAccount.UserAccountString);
    }