Question

更新模型时，UI会相应更新，但是当我更新具有双向绑定的文本框时，不会调用视图模型中的setter。我做错了什么？

以下是视图模型绑定视图的方式

public partial class MyView : MetroWindow
{
    public MyView()
    {
        try
        {
            InitializeComponent();
            DataContext = new MyViewModel(new DialogService(this));
        }
        catch (Exception exception)
        {
            throw exception;
        }
    }
}

XAML

<TextBox x:Name="TextBox1" Grid.Column="0" Text="{Binding SelectedEntity.Prop1, >Mode=TwoWay}"
controls:TextBoxHelper.ClearTextButton="True"
controls:TextBoxHelper.IsWaitingForData="True"
controls:TextBoxHelper.UseFloatingWatermark="True"
controls:TextBoxHelper.Watermark="{x:Static >properties:Resources.Prop1}" />
<TextBox x:Name="TextBox2" Grid.Column="0" Text="{Binding SelectedEntity.Prop2}"
controls:TextBoxHelper.ClearTextButton="True"
controls:TextBoxHelper.IsWaitingForData="True"
controls:TextBoxHelper.UseFloatingWatermark="True"
controls:TextBoxHelper.Watermark="{x:Static >properties:Resources.Prop2}"/>

视图模型

public class MyViewModel : IMyViewModel, INotifyPropertyChanged 
{

   private readonly IDialogService _dialogService;
   public event PropertyChangedEventHandler PropertyChanged;
    private readonly MyModel _model;
    private MyEntity _selectedEntity;

public MyViewModel(IDialogService dialogService)
{
    _dialogService = dialogService;

    _selectedEntity = new MyEntity();
    _model = new MyModel();
    _model.PropertyChanged += _model_PropertyChanged;
}

public MyEntity SelectedEntity 
{
    get
    {
            var information = _model.GetInformation();
            _selectedEntity.Flight = information.Prop1;
            information.Destination = information.Prop2;
            return _selectedEntity;
    }
    set
    {
        _selectedEntity = value;
        OnPropertyChanged("SelectedEntity");
    } 
}

private void OnPropertyChanged(string propertyName)
{
     PropertyChanged?.Invoke(this, new          PropertyChangedEventArgs(propertyName));
}

 }

Answer 1

<TextBox x:Name="TextBox1" Grid.Column="0" Text="{Binding SelectedEntity.Prop1, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"

TextBox的默认UpdateSourceTrigger是LostFocus我相信，所以你需要明确地将它设置为PropertyChanged。这样，只要属性发生变化，它就会触发。

Answer 2

为了记录，即使双向绑定也不足够。似乎从绑定实例更新值时不会调用绑定程序实例的setter，即使您成功为旧值分配了新值也是如此。您需要在声明期间设置Dependency属性的PropertyChangedCallback回调以捕获此更改。

详细信息： https://docs.microsoft.com/en-us/dotnet/api/system.windows.propertychangedcallback?view=netframework-4.8

WPF双向绑定未从UI更新

2 个答案: