Dynamically binding and statically adding MenuItems - using view Models/MVVM

问题

I'm trying to have a dynamic menu item using MVVM from an observable collection. Everything worked, but then I needed to add a "add new" button to the end. I found a solution using a CompositeCollection, like here:

How do I dynamically bind and statically add MenuItems?

So have the following code, where TimeSpans is a collection of ViewModels:

    <MenuItem Header="Time Ranges">
        <MenuItem.ItemsSource>
            <CompositeCollection>
                <CollectionContainer Collection="{Binding TimeSpans}" />
                <Separator />
                <MenuItem Header="Add New" cal:Message.Attach="NewTimeSpan()" />
            </CompositeCollection>
        </MenuItem.ItemsSource>
        <MenuItem.ItemTemplate>
            <ItemContainerTemplate>
                <MenuItem Header="{Binding Name}" cal:Message.Attach="ConfigureTimeSpan()" />
            </ItemContainerTemplate>
        </MenuItem.ItemTemplate>
    </MenuItem>

However, the view models are not populated like it was just using ItemsSource="{Binding TimeSpans}", it's not showing anything:

I suspect this is because I'm in the StackOverflow answer above the binding is actually a collection of MenuItems, so that composite collection makes sense. Whereas mine's mixing ViewModels & MenuItems.

Is there any way to construct the collection of menu-items created from ViewModels in the XAML so I can bind it?

回答1:

For anyone else who comes across this, as Szabolcs Dezsi said, I needed to use a resource for the CollectionViewSource (bad reading comprehension on my part, as that was in the answer linked in my question).

Working code below:

<MenuItem Header="Time Ranges" x:Name="TimeRangesMenuItem">
    <MenuItem.Resources>
        <CollectionViewSource Source="{Binding ElementName=TimeRangesMenuItem, Path=TimeSpans}" x:Key="TimeSpanMenuItems" />
    </MenuItem.Resources>
    <MenuItem.ItemsSource>
        <CompositeCollection>
            <CollectionContainer Collection="{Binding Source={StaticResource TimeSpanMenuItems}}" />
            <Separator />
            <MenuItem Header="Add New" cal:Message.Attach="NewTimeSpan()" />
        </CompositeCollection>
    </MenuItem.ItemsSource>
    <MenuItem.ItemTemplate>
        <ItemContainerTemplate>
            <MenuItem Header="{Binding Name}" cal:Message.Attach="ConfigureTimeSpan()" />
        </ItemContainerTemplate>
    </MenuItem.ItemTemplate>
</MenuItem>

来源：https://stackoverflow.com/questions/35688543/dynamically-binding-and-statically-adding-menuitems-using-view-models-mvvm

标签

wpf

mvvm

compositecollection