Question

我有以下ViewModel：

public class TransportationUnit : ViewModelBase {
    private string _TypeOfFuel;
    private string _Model;
    private string _Manufacturer;
    private string _LicencePlate;
    private Guid _Key = Guid.Empty;

    public ICommand CmdAddTransportationUnit { get; set; }

    public TransportationUnit() {
        CmdAddTransportationUnit = new GalaSoft.MvvmLight.Command.RelayCommand( () => AddTransportationUnitDo(), () => AddTransportationUnitCan() );
    }

    /// <summary>manufacturer</summary>
    public string Manufacturer {
          get { return _Manufacturer; }
          set {
            if (_Manufacturer == value )
                return;
            RaisePropertyChanging( "Manufacturer" );
            _Manufacturer = value;
            RaisePropertyChanged( "Manufacturer" );
        }
    }

    /* ommitted some equal properties */

    public bool AddTransportationUnitCan() {
        return !string.IsNullOrWhiteSpace( Model ) && !string.IsNullOrWhiteSpace( Manufacturer ) & !string.IsNullOrWhiteSpace( LicencePlate );
    }

    public async void AddTransportationUnitDo() {
        await LogbookRepository.Instance.Add<TransportationUnit>( this );
    }
}

我的文本框以这种方式绑定：

<TextBox x:Name="CarManufacturerNameText" Width="400" HorizontalAlignment="Left" VerticalAlignment="Center" Grid.Row="0" Grid.Column="1" Text="{Binding Manufacturer,Mode=TwoWay}" />

AppBar（底部）中的我的按钮是这样绑定的：

<Button Style="{StaticResource SaveAppBarButtonStyle}" AutomationProperties.Name="" x:Name="save" x:Uid="StandardSave" Command="{Binding CmdAddTransportationUnit}" />

我希望当方法AddTransportationUnitCan评估为false时禁用该按钮，反之亦然。当所有文本框都被填充时，它会一直被禁用，甚至方法中设置的断点也只在创建RelayCommand时触发一次。我已经测试了很长时间，但还没有找到解决方案。其他人有这个问题吗？

修改：当我在AddTransportationUnitCan中返回true时按钮已启用

Answer 1

尝试将RaiseCanExecuteChanged添加到您的属性设置器中。这将告诉您的RelayCommand重新评估CanExecute。

public string Manufacturer {
          get { return _Manufacturer; }
          set {
            _Manufacturer = value;
            RaisePropertyChanged( "Manufacturer" );
            CmdAddTransportationUnit.RaiseCanExecuteChanged(); 
        }
    }

MVVMLight：RelayCommand似乎无法在Windows 8 App中运行

1 个答案: