CODEWITHSUNDEEP
c#wpfmvvmcombobox
The man holds me down at 1 Rep
The man holds me down at 1 Rep

Reputation: 117

Why isn't this combobox displaying items?

I'm writing an import utility, I'd like for users to be able to upload from a CSV and then direct the columns where they'd like them to go.

So in order to do this, I'm making the header of each column a ComboBox populated with all of the possible columns.

xaml

        <DataGrid x:Name="ImportTable" 
                  ItemsSource="{Binding displayTable}"
                  AutoGeneratingColumn="OnAutoGeneratingColumn"
                  AutoGenerateColumns="True"
                  CanUserAddRows="True" 
                  CanUserDeleteRows="True"
                  EnableColumnVirtualization="True"
                  EnableRowVirtualization="True"
                  MaxWidth="1300"
                  MaxHeight="600"
                  />

xaml.cs

    private void OnAutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
    {

        var cb = new ComboBox();
        foreach (DataColumn test in (DataContext as EnterValueDialogViewModel).displayTable.Columns)
            Console.Out.WriteLine(test);

        cb.ItemsSource = (DataContext as EnterValueDialogViewModel).displayTable.Columns;
        e.Column.Header = cb;
    }

This correctly prints out all of the columns, but nothing is actually displayed inside of the combo box's

Empty Combobox

The combobox now displays properly in the dropdown. but i can't get it's selectedValue to set. The following code prints out that the selectedvalue is correct, but it's still populating initially as blank/unselected

        var cb = new ComboBox();
        cb.DisplayMemberPath = "ColumnName";
        cb.SelectedValue = e.PropertyName.ToString();
        cb.ItemsSource = (DataContext as EnterValueDialogViewModel).displayTable.Columns;
        Console.Out.WriteLine(cb.SelectedValue);
        e.Column.Header = cb;

Upvotes: 0

Views: 53

Answers (2)

Cleaven
Cleaven

Reputation: 974

You need to set the DisplayMemberPath and the SelectedValuePath of the combo box I think.

These will be column names from your data file.

It should look something like this:

private void OnAutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
{
    var cb = new ComboBox();
    foreach (DataColumn test in (DataContext as EnterValueDialogViewModel).displayTable.Columns)
        Console.Out.WriteLine(test);

    cb.ItemsSource = (DataContext as EnterValueDialogViewModel).displayTable.Columns;
    cb.DisplayMemberPath = "Column1";
    cb.SelectedValuePath = "Column2";
    e.Column.Header = cb;
}

Let me know if it helped.

Upvotes: 0

Sudsy1002
Sudsy1002

Reputation: 598

You can try to set the DisplayMemberPath of your combobox.

    private void OnAutoGeneratingColumn(object sender, DataGridAutoGeneratingColumnEventArgs e)
    {

        var cb = new ComboBox();
        cb.DisplayMemberPath = "SomePropertyFromYourCollection";
        foreach (DataColumn test in (DataContext as EnterValueDialogViewModel).displayTable.Columns)
            Console.Out.WriteLine(test);

        cb.ItemsSource = (DataContext as EnterValueDialogViewModel).displayTable.Columns;
        e.Column.Header = cb;
    }

Documentation here.

Upvotes: 1

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