如何为 WPF 实现可选列表

Question

这似乎是一个简单的问题让我困惑了一段时间，所以我很感激一些建议。

我需要实现可选列表以在 WPF 中使用。由于列表可能很长，用户通常只会选择几个项目，我认为最好的方法是只获取一次完整列表，然后只列出我的主对象（MyParent）的每个实例的选定对象。 MyParent 也可以多次实例化，用户通常一次使用多个实例。我希望用户能够查看包含可能项目的整个列表并能够选择他们想要的内容。我不确定如何绑定这些属性

我的代码（简化和通用名称）：

// item model:
public class MyItem
{
    public int ItemId { get; set; }
    public string ItemName { get; set; }
    public bool IsSelected { get; set; } = false;
}

// items factory (ideally entire list should only be
// pulled once in a program lifetime hence singleton):
public class MyItemsFactory
{
    private ObservableCollection<MyItem> myItems => new ObservableCollection<MyItem>();
    public static ObservableCollection<MyItem> MyItems => Instance.myItems;

    private MyItemsFactory()
    {
        GetItems();
    }
    private void GetItems()
    {
        // generate some sample data
        var i1 = new MyItem() { ItemId = 1, ItemName = "Item 1" };
        var i2 = new MyItem() { ItemId = 2, ItemName = "Item 2" };
        var i3 = new MyItem() { ItemId = 3, ItemName = "Item 3" };
        var i4 = new MyItem() { ItemId = 4, ItemName = "Item 4" };
        myItems.Add(i1);
        myItems.Add(i2);
        myItems.Add(i3);
        myItems.Add(i4);
    }

    #region Singleton Implementation
    private static readonly Lazy<MyItemsFactory> instance = new Lazy<MyItemsFactory>(() => new MyItemsFactory());
    public static MyItemsFactory Instance => instance.Value;
    #endregion
}

// parent class
public class MyParent
{
    public int ParentId { get; set; }
    public ObservableCollection<MyItem> MySelectedItems { get; set; } = new ObservableCollection<MyItem>();
    public MyParent()
    {
        GetSelectedItems();
    }
    private void GetSelectedItems()
    {
        // generate some sample data
        var si2 = new MyItem() { ItemId = 2, ItemName = "Item 2", IsSelected = true };
        var si4 = new MyItem() { ItemId = 4, ItemName = "Item 4", IsSelected = true };
        MySelectedItems.Add(si2);
        MySelectedItems.Add(si4);
        // how to include remaining MyItemsFactory.MyItems here?
    }
}

我的用户控件：

<!-- DataContext is set to one of the instance of MyParent -->
<ListView ItemsSource="{Binding MySelectedItems}">
    <ListView.View>
        <GridView>
            <GridViewColumn Header="Selected">
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <ToggleButton
                            IsChecked="{Binding IsSelected}"
                            Content="Selected"/>
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>
            <GridViewColumn Header="Item Name">
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <ToggleButton Content="Selected"
                                        IsChecked="{Binding IsSelected}"
                                        Command="{x:Static c:CommandManager.SelectItem}"
                                        CommandParameter="{Binding}"/>
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>
        </GridView>
    </ListView.View>
</ListView>

这很好用，但当然只显示 MySelectedItems。我的意图是根据 MyParent 实例的 MySelectedItems 显示所有项目（例如来自 MyItemsFactory.MyItems 的项目）。非常感谢。

Answer 1

暴露MyParent中所有项目的单例集：

public class MyParent
{
    public MyItems 
    {
        get
        {
            return MyItemsFactory.MyItems;
        }
    }
}

ListView 然后可以绑定到该属性：

<!-- DataContext is set to one of the instance of MyParent -->
<ListView ItemsSource="{Binding MyItems}">
...