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我有一个程序，我可以在其中更改comboBox. 我之前在这个问题中谈到过。无论如何，我现在正在使用自定义集合，因为observableCollection没有selectedItem属性。自定义集合中有一个selectedItem属性，但我只是不确定如何设置它以便保存数据。

自定义集合类

public class MyCustomCollection<T>: ObservableCollection<T>
{
    private T _mySelectedItem;

    public MyCustomCollection(IEnumerable<T> collection) : base(collection) { }

    public T MySelectedItem
    {
        get { return _mySelectedItem; }
        set
        {
            if (Equals(value, _mySelectedItem)) return;
            _mySelectedItem = value;
            OnPropertyChanged(new PropertyChangedEventArgs("MySelectedItem"));
        }
    }
}

ViewModel - 我在其中更改集合comboBox并selectedItem为每个集合设置

//Property for the selected command in the LIST BOX
//**For clarity: the collection in the comboBox is changed based on what is
//selected in the list box
public string SelectedCommand
{
    get { return _selectedCommand; }
    set
    {
        _selectedCommand = value;
        NotifyPropertyChange(() => SelectedCommand);

        if (SelectedCommand == "1st Collection of type A")
        {
            ComboBoxEnabled = true;
            ComboBoxList = new MyCustomCollection<string>(collectionA);
            //collectionA.MySelectedItem = ??(What would I put here?) 
        }
        if (SelectedCommand == "2nd Collection of type A")
        {
            ComboBoxEnabled = true;
            ComboBoxList = new MyCustomCollection<string>(collectionA);
            //collectionA.MySelectedItem = ??(What would I put here?)
        }
    }
}

MySelectedItem我将如何为我创建并添加到的每个新集合分配一个值comboBox？这将使每当我切换到 中的不同集合时comboBox，selectedItem都会显示 。

更新

我的收藏现在设置为ObservableCollection<string>.

XAMLListBox和ComboBox

<ListBox ItemsSource="{Binding Model.CommandList}" SelectedItem="{Binding Model.SelectedCommand}" ... />

<ComboBox ItemsSource="{Binding Model.ComboBoxList}" SelectedItem="{Binding Model.SelectedOperation}"  ... />

**SelectedCommand以下新物业ListBox：

public string SelectedCommand
{
    get { return _selectedCommand; }
    set
    {
        _selectedCommand = value;
        NotifyPropertyChange(() => SelectedCommand);

        switch (SelectedCommand)
        {
            case "Collection A":
                {
                    ComboBoxList = CollectionA;
                    break;
                }
            case "Collection B":
                {
                    ComboBoxList = CollectionB;
                    break;
                }
        }
        NotifyPropertyChange(() => ComboBoxList);
    }
}

该程序仍然没有保留selectedItem为每个集合选择的那个。我一定是忘记了，或者不明白什么。

4

1 回答 1

0

您不需要自定义集合来绑定所选项目。以下是如何完成此操作的示例：

   <StackPanel>
        <!-- your listbox -->
        <ListBox x:Name="listbox">
            <sys:String>Fruits</sys:String>
            <sys:String>Vegetables</sys:String>
            <sys:String>Others</sys:String>
            <i:Interaction.Triggers>
                <i:EventTrigger EventName="SelectionChanged">
                    <i:InvokeCommandAction Command="{Binding SelectionChangedCommand}" CommandParameter="{Binding ElementName=listbox, Path=SelectedItem}"/>
                </i:EventTrigger>
            </i:Interaction.Triggers>
        </ListBox>

        <!-- your combo box -->
        <ComboBox ItemsSource="{Binding Items}" SelectedItem="{Binding CurrentItem}"/>
    </StackPanel>

xaml 包含一个ListBox带有项目（在此示例中为简单字符串）和一个SelectionChangedCommand在列表中的选择发生更改时调用的命令。

这是视图模型

public class MainWindowViewModel : NotificationObject
{
    // your collections
    private ObservableCollection<string> fruits;
    private ObservableCollection<string> vegetables;
    private ObservableCollection<string> others;

    public MainWindowViewModel()
    {
        fruits = new ObservableCollection<string>
            {
                "Apple", "Banana"
            };
        vegetables = new ObservableCollection<string>
            {
                "Tomato", "Cabbage"
            };
        others = new ObservableCollection<string>
            {
                "Pizza", "Steak"
            };

        SelectionChangedCommand = new DelegateCommand<string>(item =>
            {
                // When user selects item in the listbox change the collection of your comboBox
                switch (item)
                {
                    case "Fruits":
                        {
                            Items = fruits;
                            break;
                        }
                    case "Vegetables":
                        {
                            Items = vegetables;
                            break;
                        }
                    case "Others":
                        {
                            Items = others;
                            break;
                        }
                }

                // Raise property change to make combobox update
                RaisePropertyChanged(() => Items);
            });               
    }

    // the collection currently displayed in the comboBox
    public ObservableCollection<string> Items { get; set; }

    // The selected item of the combobox
    public string CurrentItem { get; set; }

    public DelegateCommand<string> SelectionChangedCommand { get; set; }
}

ViewModel 包含：

  1. 多个私人收藏（水果、蔬菜等）

  2. Items这是一个集合属性，表示ComboBox基于 ListBox` 中的选择的当前项目。

  3. CurrentItem绑定到 的SelectedItem属性ComboBox。

  4. SelectionChangedCommand调用时，会根据给定的参数（ 中的选定项ListBox）更改集合。

请注意，此示例使用Prism框架，但您可以使用任何支持命令的MVVM 框架来实现这一点。

如果您没有使用任何框架，只需将“命令”中的代码视为每当ListBox更改选择项时执行的代码（但是您已经实现了）。

希望这可以帮助

于 2013-10-10T19:06:53.510 回答