WPF bind enum to combobox

Question

In my WPF UserControl I need to bind an Enum on a ComboBox. This enum is declared locally:

public partial class ViewerDataConfiguration : UserControl
{
    private ViewerDataConfigurationViewModel PageViewModel;
    public Visibility IsParametriSelected { get; set; }

    public IEnumerable<eDatoAlarmMode> EnumAlarmModes {
        get
        {
            return Enum.GetValues(typeof(eDatoAlarmMode)).Cast<eDatoAlarmMode>();
        }
    }

On the main Grid, where there is a collection bound, I defined a ComboBox as follows:

<TextBox Grid.Column="16" Text="{Binding ConfigObject.Edit.Source}" Style="{StaticResource txtDataStyle2}" Width="30" Visibility="{Binding ConfigObject.Edit, Converter={StaticResource ListaValoriVisibilityConverter}}" HorizontalAlignment="Stretch" TextChanged="Data_TextChanged" />
<Label Grid.Column="17" Content="AlarmMode" Style="{StaticResource labelStyle2}" />
<ComboBox Grid.Column="18" Width="30"
          ItemsSource="{Binding Path=EnumAlarmModes, RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=local:ViewerDataConfiguration}}"
          DisplayMemberPath="Value"
          SelectedValuePath="Value" Style="{StaticResource comboUsersStyle}" />

Basically seems that my IEnumerable is not bound correctly. I see the elements but they're blank. Any hint?

Martin Zikmund · Accepted Answer · 2018-02-09 09:45:01Z

3

You are using DisplayMemberPath and SelectedValuePath attributes, but your collection item type is just a simple string, and want to use this entire instance directly, so you should remove these attributes and it should work as expected.

You also need to change the field to a property as data binding works only on properties, not class fields (although x:Bind in UWP no longer has this limitation):

  public IEnumerable<AlarmMode> EnumAlarmModes
    {
        get
        {
            return Enum.GetValues(typeof(AlarmMode)).Cast<AlarmMode>();
        }
    }

If you want to display enum values instead of names, create a value converter:

public class EnumValueConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
    {
        return (int)value;
    }

    public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
    {
        throw new NotImplementedException();
    }
}

And then use it in the ItemTemplate:

<ComboBox Grid.Column="18" Width="100"

    ItemsSource="{Binding Path=EnumAlarmModes}">
    <ComboBox.Resources>
        <local:EnumValueConverter x:Key="EnumValueConverter" />
    </ComboBox.Resources>
    <ComboBox.ItemTemplate>
        <DataTemplate>
            <TextBlock Text="{Binding Converter={StaticResource EnumValueConverter}}" />
        </DataTemplate>
    </ComboBox.ItemTemplate>     
</ComboBox>

For this to work you also have to add a xmlns:local declaration to your Window:

xmlns:local="clr-namespace:NamespaceOfConverter"

edited Feb 9, 2018 at 9:45

answered Feb 9, 2018 at 9:22

Martin Zikmund

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5 Comments

John Goodman Over a year ago

I slightly modified the code, as in effect a IEnumerable of string is not usefu as I need to bind name and value in the combobox. So the property now is: public IEnumerable<eDatoAlarmMode> EnumAlarmModes { get { return Enum.GetValues(typeof(eDatoAlarmMode)).Cast<eDatoAlarmMode>(); } } And I restored the DisplayMemberPath="Value" SelectedValuePath="Name"

John Goodman Over a year ago

Nope... my enum contains 3 items, I only see 3 empty items binded in the combobox

Martin Zikmund Over a year ago

Remove the DisplayMemberPath and SelectedValuePath attributes, it works well without them.

Martin Zikmund Over a year ago

Also if you want to display enum value instead of name, I have updated my answer with the solution.

Martin Zikmund Over a year ago

Awesome :-) . Happy coding!

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