Question

我希望能够将ListBox绑定到List<>或ObservableCollection<>，并且能够在保持绑定的同时更改列表本身。

在ViewModel中：

public event PropertyChangedEventHandler PropertyChanged;
protected void RaisePropertyChangedEvent(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));

private ObservableCollection<string> items = new ObservableCollection<string>();
public ObservableCollection<string> Items
{
    get
    {
        return items;
    }
    set
    {
        items = value;
        RaisePropertyChangedEvent(nameof(Items));
    }
}

private void FillItems()
{
    Items1 = new ObservableCollection<string>();
    Items.Add("1");
    Items.Add("2");
}

在视图中：

<ListBox x:Name="listBox" ItemsSource="{Binding Items}"/>

现在，当我调用FillItems()函数时，列表不会显示项目。但如果我改变下面的代码，它将起作用：

private void FillItems()
{
    Items.Clear();
    Items.Add("1");
    Items.Add("2");
}

Answer 1

确保视图模型实现INotifyPropertyChanged并在目标属性发生更改时通知视图。

使用以下简单视图

<Window x:Class="WpfApplication1.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
        xmlns:local="clr-namespace:WpfApplication1"
        mc:Ignorable="d"
        Title="MainWindow" Height="350" Width="525">
    <Grid >
        <Grid.RowDefinitions>
            <RowDefinition Height="*"/>
            <RowDefinition Height="auto"/>
        </Grid.RowDefinitions>
        <ListBox x:Name="listBox" ItemsSource="{Binding Items}"/>
        <Button Grid.Row="1" Content="Fill" Click="Button_Click" />
    </Grid>
</Window>

以下代码和视图模型

namespace WpfApplication1 {
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window {
        private MainViewModel viewModel;

        public MainWindow() {
            InitializeComponent();
            viewModel = new MainViewModel() {
                Items = new List<string>() {
                     "a", "b"
                }
            };
            this.DataContext = viewModel;
        }

        private void Button_Click(object sender, RoutedEventArgs e) {
            viewModel.FillItems();
        }
    }

    public class MainViewModel : INotifyPropertyChanged {
        public event PropertyChangedEventHandler PropertyChanged;
        protected void RaisePropertyChangedEvent(string propertyName) => PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
        Random random = new Random();

        private List<string> items = new List<string>();
        public List<string> Items {
            get {
                return items;
            }
            set {
                items = value;
                RaisePropertyChangedEvent(nameof(Items));
            }
        }

        public void FillItems() {    
            var list = Enumerable.Range(0, 10).Select(i => random.Next(100).ToString()).Distinct().ToList();
            Items = new List<string>(list);
        }
    }
}

每次点击该按钮时，ListBox和List都会按预期更新ObservableCollection。

您应该再次检查您的代码，并确保遵循可能影响您的代码的常见做法，因为您在示例中提供的内容应该有效。

ListBox与更改的通用List的数据绑定

1 个答案: