从Collection创建MenuItems(Create MenuItems from Collection)

 我试图创建收集项的MenuItems - 并失败。 详细说明：我有一个简单的类ClassA，它定义了一个字符串属性'HeadText'。 在我的MainViewModel中，我定义了一个ObservableCollection属性。 该系列包含3个项目。 现在在XAML中，我想创建这三个ClassA类型的MenuItems。 我做了以下事情： 
 
<Window.Resources>
    <CompositeCollection x:Key="CollA">
        <ItemsControl ItemsSource="{Binding Path=MItems}">
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <MenuItem Header="{Binding HeadText}"/>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </CompositeCollection>
</Window.Resources>

<Grid>
    <Menu DockPanel.Dock="Top" ItemsSource="{Binding Source={StaticResource CollA}}"/>
</Grid>
 
 但我得到的只是一个空的菜单栏。 我有什么想法可以做到这一点？ 
 
 viewmodel和类ClassA： 
 
public class MainVM
{
    public MainVM() {
        _mItems.Add(new ClassA() { HeadText = "A" });
        _mItems.Add(new ClassA() { HeadText = "B" });
        _mItems.Add(new ClassA() { HeadText = "C" });
    }

    private ObservableCollection<ClassA> _mItems = new ObservableCollection<ClassA>();
    public ObservableCollection<ClassA> MItems{
        get { return _mItems; }
    }
}

public class ClassA
{
    public ClassA() { }
    public String HeadText { get; set; }
}
 
 提前致谢。 
 
 编辑： 
 
 如果我写这个，它的工作原理： 
 
<Menu DockPanel.Dock="Top" ItemsSource="{Binding MItems}">
    <Menu.ItemContainerStyle>
        <Style TargetType="MenuItem" BasedOn="{StaticResource {x:Type MenuItem}}">
            <Setter Property="Header" Value="{Binding HeadText}"/>
        </Style>
    </Menu.ItemContainerStyle>
</Menu>
 
 但我想以另一种方式做到这一点。 我很感兴趣为什么另一种方式不起作用。 

i tried to create MenuItems of collection items - and failed. In detail: I have a simple class ClassA that defines a string-property 'HeadText'. In my MainViewModel i defined an ObservableCollection property. The collection is filled with 3 items. Now in XAML i want to create MenuItems of these 3 items of type ClassA. I did the following:
 
<Window.Resources>
    <CompositeCollection x:Key="CollA">
        <ItemsControl ItemsSource="{Binding Path=MItems}">
            <ItemsControl.ItemTemplate>
                <DataTemplate>
                    <MenuItem Header="{Binding HeadText}"/>
                </DataTemplate>
            </ItemsControl.ItemTemplate>
        </ItemsControl>
    </CompositeCollection>
</Window.Resources>

<Grid>
    <Menu DockPanel.Dock="Top" ItemsSource="{Binding Source={StaticResource CollA}}"/>
</Grid>
 
But all i get is an empty menu bar. Any ideas how i can do this?
 
The viewmodel and the class ClassA:
 
public class MainVM
{
    public MainVM() {
        _mItems.Add(new ClassA() { HeadText = "A" });
        _mItems.Add(new ClassA() { HeadText = "B" });
        _mItems.Add(new ClassA() { HeadText = "C" });
    }

    private ObservableCollection<ClassA> _mItems = new ObservableCollection<ClassA>();
    public ObservableCollection<ClassA> MItems{
        get { return _mItems; }
    }
}

public class ClassA
{
    public ClassA() { }
    public String HeadText { get; set; }
}
 
Thanks in advance.
 
Edit:
 
If i write this, it works:
 
<Menu DockPanel.Dock="Top" ItemsSource="{Binding MItems}">
    <Menu.ItemContainerStyle>
        <Style TargetType="MenuItem" BasedOn="{StaticResource {x:Type MenuItem}}">
            <Setter Property="Header" Value="{Binding HeadText}"/>
        </Style>
    </Menu.ItemContainerStyle>
</Menu>
 
But i want to do it the other way. And i'm interested why the other way does not work.

原文：https://stackoverflow.com/questions/28432867