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I am trying to simply populate a ComboBox with data from a Sql server table column (adhering to the MVVM design pattern), and do not understand why it is not working. I am binding it to a BindableCollection (Stylet framework), which is basically an ObservableCollection.
There is automatic coupling between the View and the ViewModel (Stylet does this).

This is my method:

public void FillComboBoxLicenseHolders() {

    try {

        DataSet ds = new DataSet();

        using (SqlConnection sqlCon = new SqlConnection(ConnectionString.connectionString)) {

            SqlDataAdapter sqlDA = new SqlDataAdapter();
            sqlDA.SelectCommand = new SqlCommand("select Foretaksnavn from tblLicenseHolder", sqlCon);

        DataTable dt = new DataTable();
        dt = ds.Tables[0];

        for (int i = 0; i < dt.Rows.Count; i++) {

            DataRow dr = dt.NewRow();
            dr = dt.Rows[i];
            LicenseHolder licenseHolder = new LicenseHolder();
            licenseHolder.Foretaksnavn = dr["Foretaksnavn"].ToString();


    } catch (Exception ex) {

        MessageBox.Show(ex.Message, "Message", MessageBoxButton.OK, MessageBoxImage.Information);

This is how I instantiate my BindableCollection:

private BindableCollection<LicenseHolder> _licenseHolders;
public BindableCollection<LicenseHolder> LicenseHolders {

    get => _licenseHolders;
    set => SetAndNotify(ref this._licenseHolders, value);

public TripViewModel(IWindowManager windowManager) {

    this.windowManager = windowManager;
    LicenseHolders = new BindableCollection<LicenseHolder>();

This is my ComboBox in the XAML:

<ComboBox Name="cbLicenseHolder" Canvas.Left="50" Canvas.Top="204" Width="291"
          ItemsSource="{Binding LicenseHolders, Mode=TwoWay}"
          Loaded="{s:Action FillComboBoxLicenseHolders}"/>

What I have tried:

I've spent the better part of a day trying to Google my way through this..

When I run my app, there's no error message, but the ComboBox displays no results.
If I debug and put a break point, I can see that it does indeed read the sql server column data, but it is still not showing.

Any ideas?
Chris Copeland 5-Aug-21 10:18am
I can't immediately see a problem with this code, how are you binding the ViewModel to the Window itself? And are you using the ComboBox within a template or style? Have you confirmed that the query is loading values from the database, ie. check with a debugger to step through the code?

I will note that the ComboBox isn't provided with a DisplayMemberPath so it will probably try to call ToString() on each of the objects in the collection.
olegul86 5-Aug-21 11:52am
Hi @Chris Copeland, and thanks for your response. The framework takes care of the coupling between the ViewModel and the View, which has worked nicely on other parts of my app. I do not think I am using the ComboBox within a template or a style, and I'm not sure completely sure what that means. I did step through the code, and the for loop in my method is able to count all 8 rows in my sql table column, and when I get to "LicenseHolders.Add(licenseHolder); it does in fact hold the first row.
Gerry Schmitz 5-Aug-21 17:42pm
You did not specify a "member" to display, so the combobox is going to use thatever is returned by your "combo item's" ToString() method. Assuming the Combox actually has items, isn't collapsed / not visible; which you didn't confirm using debug.
olegul86 6-Aug-21 5:49am
Thank you very much!

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