Question

请分析以下代码段：

<TextBox x:Name="TxtBox_CommandInfo"  Style="{DynamicResource MetroTextBox}"
    IsReadOnly="True" Controls:TextBoxHelper.Watermark="This is a textbox" 
    HorizontalAlignment="Left" Margin="0,236,0,0" TextWrapping="Wrap"
    VerticalAlignment="Top" Height="154" Width="780" 
    ScrollViewer.HorizontalScrollBarVisibility="Auto" 
    ScrollViewer.VerticalScrollBarVisibility="Auto">
  <TextBox.Text>
    <MultiBinding StringFormat="{}{0} {1} {2}" NotifyOnTargetUpdated="True">
      <Binding  Path="A" />
      <Binding  Path="B" />
      <Binding  Path="C"/>
      <Binding Path="D" Mode="TwoWay" NotifyOnTargetUpdated="True"
          UpdateSourceTrigger="PropertyChanged"/>
    </MultiBinding>
  </TextBox.Text>
</TextBox>

正如您所看到的那样TxtBox_CommandInfo文本框文本（目标）值将仅由A,B,C修改/格式化，但更新的文本应通过binding.Model通知D。如下：

A,B,C =＆gt; [TexBox.Text] =＆gt; D

问题是C＃方面的相应来源D在TxtBox_CommandInfo.Text发生变更时未获得通知和更新。

没有任何Converters如何解决此问题？
我是否错误配置了Multibinding设置？

确实需要StringFormat功能，因此如果没有注入转换，我们是否有StringFormat的替代方案？

Answer 1

我仍然感到困惑。不确切地知道你的意思：

我在评论中试图解释，这是一个解决方案。

XAML：

 <Grid>
    <StackPanel>
        <ComboBox ItemsSource="{Binding Path=MyTexts}" SelectedItem="{Binding Path=A}" Margin="10"/>
        <ComboBox ItemsSource="{Binding Path=MyTexts}" SelectedItem="{Binding Path=B}" Margin="10"/>
        <ComboBox ItemsSource="{Binding Path=MyTexts}" SelectedItem="{Binding Path=C}" Margin="10"/>

        <TextBox Height="80" Margin="10" Text="{Binding Path=D, Mode=OneWay}" IsReadOnly="True" AcceptsReturn="True" TextWrapping="Wrap">
        </TextBox>
    </StackPanel>
</Grid>

C＃:( ViewModel）

 public class MyViewModel : INotifyPropertyChanged
{
    private string _a;
    private string _b;
    private string _c;

    public string A
    {
        get => _a;
        set
        {
            _a = value;
            OnPropertyChanged(nameof(A));
            OnPropertyChanged(nameof(D));
        }
    }
    public string B
    {
        get => _b;
        set
        {
            _b = value;
            OnPropertyChanged(nameof(B));
            OnPropertyChanged(nameof(D));
        }
    }
    public string C
    {
        get => _c;
        set
        {
            _c = value;
            OnPropertyChanged(nameof(C));
            OnPropertyChanged(nameof(D));
        }
    }
    public string D => $"{A} {B} {C}";

    public List<string> MyTexts { get; }

    public MyViewModel()
    {
        MyTexts = new List<string>() { "FHAKWEFJ AWKEEF AWEKF LAEWKF LAWEF", "AAAAAAAAAAAAAAAAAAAAAA", "BBBBBBBBBBBBBBBBBBBBBBBBB", "EEEEEEEEEEEEEEEEEEEEEEEEE", "GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG", "GGGGGGGGGGGGGGGGGGGGGGGGGGGGGGG" };
    }

    #region INotifyPropertyChanged
    public event PropertyChangedEventHandler PropertyChanged;

    [NotifyPropertyChangedInvocator]
    protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }

    #endregion
}

没有黑客，没有魔法，也没有任何事件。普通MVVM

修改我想这就是你想要的（只显示对上面代码的修改）：

<TextBox Height="80" Margin="10" TextChanged="TextBoxBase_OnTextChanged" IsReadOnly="True" AcceptsReturn="True" TextWrapping="Wrap"> <TextBox.Text> <MultiBinding StringFormat="{}{0} {1} {2}" NotifyOnTargetUpdated="True" Mode="OneWay"> <Binding Path="A" Mode="OneWay"/> <Binding Path="B" Mode="OneWay"/> <Binding Path="C" Mode="OneWay"/> </MultiBinding> </TextBox.Text> </TextBox>

C＃：

private void TextBoxBase_OnTextChanged(object sender, TextChangedEventArgs e) { if (this.DataContext is MyViewModel dataContext) dataContext.D = ((TextBox) sender).Text; }

C＃（VM）：

private string _d; public string D { get => _d; set { _d = value; OnPropertyChanged(nameof(D)); } }

使用WPF中的StringFormat通过Multibinding通知和更新源

1 个答案: