Question

遵循MVVM模式。每当TextBox中的Text发生更改时，我都需要TextBox来触发viewModel上的属性设置器。问题是从不调用ViewModel上的setter。这就是我所拥有的：

查看（.cs）

public partial class AddShowView : PhoneApplicationPage
{
    public AddShowView()
    {
        InitializeComponent();
    }

    private void PhoneApplicationPage_Loaded_1(object sender, RoutedEventArgs e)
    {
        DataContext = new AddShowViewModel(this.NavigationService);
    }

    private void SearchTextBox_TextChanged_1(object sender, TextChangedEventArgs e)
    {
        var textBox = (TextBox)sender;
        var binding = textBox.GetBindingExpression(TextBox.TextProperty);
        binding.UpdateSource();
    }
}

查看（.xaml），只有相关部分

<TextBox Grid.Row="0" HorizontalAlignment="Stretch" VerticalAlignment="Center" Text="{Binding SearchText, UpdateSourceTrigger=Explicit}" TextChanged="SearchTextBox_TextChanged_1" />

视图模型

public class AddShowViewModel : PageViewModel
{
    #region Commands

    public RelayCommand SearchCommand { get; private set; }

    #endregion

    #region Public Properties

    private string searchText = string.Empty;
    public string SearchText
    {
        get { return searchText; }
        set
        {
            searchText = value;
            SearchCommand.RaiseCanExecuteChanged();
        }
    }

    #endregion

    public AddShowViewModel(NavigationService navigation) : base(navigation)
    {
        SearchCommand = new RelayCommand(() => MessageBox.Show("Clicked!"), () => !string.IsNullOrEmpty(SearchText));
    }
}

从源到目标的绑定工作，我已经双重检查，因此DataContext设置正确。我不知道我哪里出错了。谢谢你的帮忙。

Answer 1

您需要将绑定模式设置为TwoWay，否则它只会从ViewModel中读取值，而不是更新它。

Text="{Binding SearchText, Mode=TwoWay, UpdateSourceTrigger=Explicit}"

绑定源不更新

1 个答案: