Question

我有以下ItemsControl，它为我提供了一个可用集合中每个数据库的复选框。这些复选框允许用户选择要过滤的那些。要过滤的数据库位于单独的集合（FilteredDatabases）中。我到底该怎么做？我可以将InFilter属性添加到数据库项类。但是，我不想开始更改此代码。我无法解决的问题是我需要绑定到不在数据库项本身上的属性。有什么想法吗？

<ItemsControl ItemsSource="{Binding AvailableDatabases}">
   <ItemsControl.ItemTemplate>
      <DataTemplate>
         <CheckBox Content="{Binding Name}" IsChecked="{Binding ???}"/>
      </DataTemplate>
   </ItemsControl.ItemTemplate>
</ItemsControl>

// In view model

public IBindingList FilteredDatabases
{
  get;
  private set;  
}

public IBindingList AvailableDatabases
{
   get;
   private set;
}

Answer 1

将CheckBox.Command绑定到路由命令实例
将路由命令绑定到方法
使用IBindingList.Add和IBindingList.Remove方法

Answer 2

以下代码说明了您要执行的操作，为了做到这一点，最好使用ObservableCollection而不是作为集合对象，如果ItemsControl绑定到它，它将在添加视图模型时自动更新UI除去。

XAML：

<Grid>
    <Grid.ColumnDefinitions>
        <ColumnDefinition />
        <ColumnDefinition />
    </Grid.ColumnDefinitions>
    <ItemsControl Grid.Column="0" ItemsSource="{Binding AvailableDatabases}">
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <CheckBox Content="{Binding Name}" IsChecked="{Binding IsChecked}"/>
            </DataTemplate>
        </ItemsControl.ItemTemplate>
    </ItemsControl>
    <ItemsControl Grid.Column="1" ItemsSource="{Binding FilteredDatabases}">
        <ItemsControl.ItemTemplate>
            <DataTemplate>
                <TextBlock Text="{Binding Name}" />
            </DataTemplate>
        </ItemsControl.ItemTemplate>
    </ItemsControl>
</Grid>

查看模特：

public class MainViewModel
{
    private ObservableCollection<DBViewModel> _availableDatabases;
    private ObservableCollection<DBViewModel> _filteredDatabases;

    public ObservableCollection<DBViewModel> AvailableDatabases
    {
        get
        {
            if (_availableDatabases == null)
            {
                _availableDatabases = new ObservableCollection<DBViewModel>(new List<DBViewModel>()
                    {
                        new DBViewModel(this) { Name = "DB1" , IsChecked = true},
                        new DBViewModel(this) { Name = "DB2" },
                        new DBViewModel(this) { Name = "DB3" },
                        new DBViewModel(this) { Name = "DB4" },
                        new DBViewModel(this) { Name = "DB5" },
                        new DBViewModel(this) { Name = "DB6" },
                        new DBViewModel(this) { Name = "DB7" , IsChecked = true },
                    });


            }
            return this._availableDatabases;
        }
    }

    public ObservableCollection<DBViewModel> FilteredDatabases
    {
        get
        {
            if (_filteredDatabases == null)
                _filteredDatabases = new ObservableCollection<DBViewModel>(new List<DBViewModel>());

            return this._filteredDatabases;
        }
    }
}

public class DBViewModel
{
    private MainViewModel _parentVM;
    private bool _isChecked;

    public string Name { get; set; }

    public DBViewModel(MainViewModel _parentVM)
    {
        this._parentVM = _parentVM;
    }

    public bool IsChecked
    {
        get
        {
            return this._isChecked;
        }
        set
        {
            //This is called when checkbox state is changed
            this._isChecked = value;

            //Add or remove from collection on parent VM, perform sorting here
            if (this.IsChecked)
                _parentVM.FilteredDatabases.Add(this);
            else
                _parentVM.FilteredDatabases.Remove(this);

        }
    }
}

View模型也应该实现INotifyPropertyChanged，我省略了它，因为在这种特殊情况下没有必要。

如何在ItemsControl中绑定CheckBox的IsChecked属性？

2 个答案: