Question

我必须在我的应用程序上绑定两次数据。我有两个列表视图。第一个是复选框中显示的所有元素的列表。第二个列表视图必须仅获取选中复选框的值。

所以我试图处理一个ViewMode和两个ObservableCollection。一个完整的，一个将被过滤。但是我不能让它发挥作用。是这样做的好方法吗？

谢谢你！

以下是XAML代码：

<!-- The full collection -->
<ListView Grid.Row="1" Grid.Column="0" ItemsSource="{Binding Cycles.MyData}">
    <ListView.View>
        <GridView AllowsColumnReorder="False">
            <GridViewColumn>
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <CheckBox Style="{DynamicResource SwitchOnly}" IsChecked="{Binding Cycles.Used, UpdateSourceTrigger=PropertyChanged}"/>
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
            </GridViewColumn>
            <GridViewColumn>
                <GridViewColumn.CellTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding Name}"/>
                    </DataTemplate>
                </GridViewColumn.CellTemplate>
        </GridViewColumn>
    </GridView>
</ListView.View>
<!-- The filtered collection -->
<ListView Grid.Column="2" Grid.Row="0" Grid.RowSpan="2" ItemsSource="{Binding Cycles.MyDataFiltered}">
    <ListView.View>
        <GridView AllowsColumnReorder="False">
            <GridViewColumn>
                 <GridViewColumn.CellTemplate>
                     <DataTemplate>
                         <CheckBox Style="{DynamicResource VisualOnly}" IsChecked="{Binding Check}"/>
                     </DataTemplate>
                 </GridViewColumn.CellTemplate>
             </GridViewColumn>
             <GridViewColumn>
                 <GridViewColumn.CellTemplate>
                     <DataTemplate>
                         <TextBlock Text="{Binding Name}"/>
                     </DataTemplate>
                 </GridViewColumn.CellTemplate>
             </GridViewColumn>
         </GridView>
     </ListView.View>
 </ListView>

这是ViewModel：

public class ViewModel : PropertyChangedBase
{
    public ObservableCollection<Cycles> MyData { get; set; }
    public ObservableCollection<Cycles> MyDataFiltered { get; set; }

    private bool _used = true;
    public bool Used
    {
        get => _used;
        set
        {
            _used = value;
            _myDataView.Filter = Filter;
            OnPropertyChanged("Used");
        }
    }

    private Cycles _currentSelectedCycle;
    public Cycles CurrentSelectedFamily
    {
        get => _currentSelectedCycle;
        private set
        {
            _currentSelectedCycle = value;
            OnPropertyChanged("CurrentSelectedFamily");
        }
    }


    readonly ICollectionView _myDataView;

    public ViewModel()
    {
        MyData = new ObservableCollection<Cycles>();
        MyDataFiltered = new ObservableCollection<Cycles>();
        _myDataView = CollectionViewSource.GetDefaultView(MyDataFiltered);
        _myDataView.CurrentChanged += delegate
        {
            CurrentSelectedFamily = (Cycles)_myDataView.CurrentItem;
        };
    }
    private static bool Filter(object item)
    {
        var value = (Cycles)item;
        return value != null && value.Check;
    }
}

这是我的Cycle类：

public class Cycles : PropertyChangedBase
{
    internal Cycles()
    {
        _check = false;
        _firstDay = 1;
    }

    private bool _check;
    private string _name;
    private int _firstDay;
    private int _lastDay;

    public bool Check
    {
        get => _check;
        set
        {
            if (_check == value) return;
            _check = value;
            OnPropertyChanged("Check");
        }
    }
    public string Name
    {
        get => _name;
        set
        {
            if (_name == value) return;
            _name = value;
            OnPropertyChanged("Name");
        }
    }
    public int FirstDay
    {
        get => _firstDay;
        set
        {
            if (_firstDay == value) return;
            _firstDay = value;
            OnPropertyChanged("FirstDay")
        }
    }
    public int LastDay
    {
        get => _lastDay;
        set
        {
            if (_lastDay == value) return;
            _lastDay = value;
            OnPropertyChanged("LastDay");
        }
    }
}
public class PropertyChangedBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;
    protected void OnPropertyChanged(string propertyName)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

Answer 1

在第二个列表中使用以下绑定

ItemsSource="{Binding SelectedCycles}"

并在视图模型中

public IEnumerable<Cycles> SelectedCycles
 {
  get { return MyData.Where(x => x.Check== true); }
 }

ViewModel中的值更改时，在ViewModel中应用过滤器

1 个答案: