Passing Enum Value as a Command Parameter

Question

Part of this question has been answered on how to bind to an enum as a command parameter, but I need to go one step further.

I have a data template that links to a menu and each menu option initiates a command with a different value of the enum. How do I do this? Do I need to resort to just passing a string?

public enum TestEnum
{
  First,
  Second,
  Third
}

<DataTemplate>
    <MenuItem Header="{Binding Path=.}" Command="{Binding ACommand}" 
        CommandParameter="{Binding Path=???}" />
</DataTemplate>

I want the first MenuItem to bind to Enum.First, the second one to Enum.Second, and so on. I want this written, so that I only have to write the data template above once within a Menu instead of a menu item for each enum.value. HTH.

I need the command parameter to be different for each menu item. So I will have 3 menu items of first, second, and third.

Do you want to binding the enum as itemssource for the menu? And set each menuItem as the enum item? — Howard, Apr 21 '11 at 14:49
My ItemsSource is a list of the values. I want to bind the enum as the itemsSource with each menu Item having an enum. — kevindaub, Apr 21 '11 at 14:53

Thomas Levesque · Accepted Answer · 2011-04-22T08:00:17.913

Not sure I understand your requirement correctly... is this what you want?

CommandParameter="{Binding Path={x:Static local:TestEnum.First}}"

EDIT: ok, I think I understand now... If you want the enum values as the ItemsSource, you could do it with an ObjectDataProvider, but there's a better way: write a markup extension that takes in the type of the enum and returns the values.

Markup extension

[MarkupExtensionReturnType(typeof(Array))]
public class EnumValuesExtension : MarkupExtension
{
    public EnumValuesExtension()
    {
    }

    public EnumValuesExtension(Type enumType)
    {
        this.EnumType = enumType;
    }

    [ConstructorArgument("enumType")]
    public Type EnumType { get; set; }

    public override object ProvideValue(IServiceProvider serviceProvider)
    {
        return Enum.GetValues(EnumType);
    }
}

XAML

<MenuItem ItemsSource="{my:EnumValues EnumType=my:TestEnum}" Name="menu">
    <MenuItem.ItemContainerStyle>
        <Style TargetType="MenuItem">
            <Setter Property="Header" Value="{Binding}" />
            <Setter Property="Command" Value="{Binding SomeCommand, ElementName=menu}" />
            <Setter Property="CommandParameter" Value="{Binding}" />
        </Style>
    </MenuItem.ItemContainerStyle>
</MenuItem>

I just think he wants to binding the enum values as the itemssource of the menu. — Howard, Apr 21 '11 at 15:20
I think you're answer is close, except if I had to guess, I'd say that daub815 intends to pass in a predetermined enum value for each of his MenuItems. — myermian, Apr 21 '11 at 19:42
I want to pass in the entire enumeration as an itemsource and the command parameter will be set to each enum in the enumeration. — kevindaub, Apr 21 '11 at 22:07
Note: {x:Static local:TestEnum.First} <- this works at runtime and in the VS designer but does not in Blend 4. — Jack Ukleja, Oct 07 '11 at 08:33

score 6 · Answer 2 · answered Apr 21 '11 at 19:40

If you want to pass a predetermined Enum value (which it sounds like you do) for the MenuItem you'd do it like so... (make sure to import the xmlns:local="..." in your xaml as well)

<MenuItem ... CommandParameter="{x:Static local:TestEnum.First}" />

You don't need to actually bind to anything for the CommandParameter in the instance that you're asking (I think). Binding a value to the CommandParameter implies that the value of the CommandParameter can vary and the source of that value is contained somewhere else, either as a value on another element's DepenedencyProperty or a CLR value within a DataContext.

Howard · Answer 3 · 2011-04-21T15:25:07.747

<ObjectDataProvider ObjectType="{x:Type sys:Enum}" MethodName="GetValues" x:Key="EnumProvider">
    <ObjectDataProvider.MethodParameters>
        <x:TypeExtension Type="{x:Type local:TestEnum}" />
    </ObjectDataProvider.MethodParameters>
</ObjectDataProvider>

<!--Binding the resource as ItemsSource-->
<Menu ItemsSource="{Binding Source={StaticResource EnumProvider}}" />

or

<Menu>
    <MenuItem Header="TestEnum" ItemsSource="{Binding Source={StaticResource EnumProvider}}" >
        <MenuItem.ItemTemplate>
            <DataTemplate>
                <MenuItem Header="{Binding Path=.}" Command="{Binding ACommand}" 
        CommandParameter="{Binding Path=???}" />
            </DataTemplate>
        </MenuItem.ItemTemplate>
    </MenuItem>
</Menu>

score 1 · Answer 4 · answered Apr 21 '11 at 15:06

1

I want to bind the enum as the itemsSource with each menu Item having an enum.

If your ItemsSource is the enum itself you can just write CommandParameter="{Binding}" and it will pass the current enum value.

answered Apr 21 '11 at 15:06

H.B.

166,899
29
327
400

Passing Enum Value as a Command Parameter

4 Answers4