C# 文本框上的StringFormat阻止输入

我需要在文本框中显示和设置汇率。 My ViewModel包含一个名为

ExchangeRate

的

decimal

属性。默认情况下，最多只能输入两位小数

汇率通常包含两位以上的小数位，因此我尝试使用StringFormat实现这一点：

        <TextBox HorizontalAlignment="Left"
             IsEnabled="{Binding ExchangeRateNeeded}"
             Text="{Binding ExchangeRate, UpdateSourceTrigger=PropertyChanged, Delay=250, Mode=TwoWay, StringFormat={}{0:0.00000}}"
             Height="23" Margin="130,92,0,0" TextWrapping="Wrap" VerticalAlignment="Top" Width="80" MaxLength="4"/>

---

您也可以显示您的ViewModel吗？

MaxLength=“4”

您确定要这样做吗？删除MaxLength=“4”哦，天哪，复制并粘贴。。。。这就解决了我的问题：（只是一个小提示，很少的例子真的很有帮助。如果你将文本框剥离到基本部分

，你会马上注意到除了绑定之外的其他问题。

 public class SetupWindowViewModel : ViewModelBase
{
    public ObservableCollection<SapVkorg> SapVkOrgs { get; }

    public SapVkorg SelectedVkOrg { get; set; }
    public ICommand OkCommand { get;  }
    public int Year { get; set; }
    public bool ApertumNumbers { get; set; }
    public ObservableCollection<Currency> Currencies { get; }
    public Currency SelectedCurrency { get; set; }
    public decimal ExchangeRate { get; set; }
    public bool ExchangeRateNeeded { get { return SelectedCurrency != Currency.EUR; }  }

    public SetupWindowViewModel(Window window) : base(window)
    {
        OkCommand = new RelayCommand(Save, CanSave);

        SapVkOrgs = mainController.GetSapVkorgs();
        Currencies = mainController.GetCurrencies();

        SelectedVkOrg = SettingsHolder.SapVkorg;
        Year = SettingsHolder.Year;
        ApertumNumbers = SettingsHolder.ApertumNumbers;
        ExchangeRate = SettingsHolder.ExchangeRate;
        SelectedCurrency = SettingsHolder.Currency;
    }


    public void Save()
    {
        SettingsHolder.SapVkorg = SelectedVkOrg;
        SettingsHolder.Year = Year;
        SettingsHolder.Currency = SelectedCurrency;
        SettingsHolder.ExchangeRate = ExchangeRate;
        SettingsHolder.ApertumNumbers = ApertumNumbers;

        CloseWindow();
    }

    public bool CanSave()
    {
        return Year > 0 &&
            SelectedVkOrg != null &&
            ((ExchangeRateNeeded && ExchangeRate != 1) || (!ExchangeRateNeeded));
    }
}

[AddINotifyPropertyChangedInterface]
public abstract class ViewModelBase
{
    protected readonly MainController mainController;
    protected static readonly log4net.ILog log = LogHelper.GetLogger();

    protected readonly Window window;

    public ICommand CloseWindowCommand { get; }

    protected ViewModelBase(Window window)
    {
        mainController = MainController.GetInstance();
        this.window = window;

        CloseWindowCommand = new RelayCommand(CloseWindow);

        Initialize();
    }

    protected void CloseWindow()
    {
        window.Close();
    }

    protected bool? ShowDialog(Window windowToOpen)
    {
        windowToOpen.Owner = window;
        return windowToOpen.ShowDialog();
    }

    private void Initialize()
    {
        window.WindowStartupLocation = WindowStartupLocation.CenterOwner;
        window.DataContext = this;
    }

    protected void DisplayAlertAndLogError(string message, Exception ex)
    {
        log.Error(message, ex);
        MessageBox.Show(message, "Fehler", MessageBoxButton.OK, MessageBoxImage.Error);
    }
}