Question

我正在使用Prism（MVVM）与WPF合作。我想设置visibililty 来自ViewModel calss的StackPanel。 StackPanel的可见性是绑定如：

 <StackPanel x:Name="spVisibility"  Orientation="Horizontal" 
          Visibility="{Binding spVisibility, Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}">

我查看模型类，如：

  public class SearchId : BindableBase, INotifyPropertyChanged
  {
      private Visibility _visibility = Visibility.Collapsed;

      private DelegateCommand<object> searchCommand;

      public event PropertyChangedEventHandler PropertyChanged;

      public SearchId()
      {
            searchCommand = new DelegateCommand<object>(this.SearchData);
      }///

       public Visibility spVisibility
       {
            get { return _visibility; }
            set
            {
                if (!string.Equals(_visibility, value))
                {
                    _visibility = value;
                    RaisePropertyChanged("spVisibility");
                }
            }
        }

        private void RaisePropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, 
                 new PropertyChangedEventArgs  (propertyName));
            }

        }

        private async void SearchData(object parameter)
        {
            _visibility = Visibility.Visible;
        }
   }

但这不起作用。请帮帮我。

Answer 1

_visibility = Visibility.Visible设置私有属性而不是使用公共属性，因此绕过了RaisePropertyChanged("spVisibility")。您需要使用spVisibility = Visibility.Visible。

Answer 2

如果您使用MVVM，我建议使用布尔值而不是可见性。 MVVM的整个目的是从DataLogic中分离View Logic。

查看逻辑：

<StackPanel Orientation="Horizontal" 
      Visibility="{Binding ShowStackPanel, Converter={StaticResource BooleanToVisibilityConverter}}">

使用转换器将boolan转换为Visibility属性.BnoleanToVisibilityConverter是.NET的一部分，无需在xaml中手动定义即可引用。

public class SearchId : BindableBase, INotifyPropertyChanged
{
  private bool _showStackPanel;

  private DelegateCommand<object> searchCommand;

  public event PropertyChangedEventHandler PropertyChanged;

  public SearchByIDVM()
  {
        searchCommand = new DelegateCommand<object>(this.SearchData);
  }///

   public bool ShowStackPanel
   {
        get { return _showStackPanel; }
        set
        {
            if (!Equals(_showStackPanel, value))
            {
                _showStackPanel= value;
                RaisePropertyChanged("ShowStackPanel");
            }
        }
    }

    private void RaisePropertyChanged(string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, 
             new PropertyChangedEventArgs  (propertyName));
        }

    }

    private async void SearchData(object parameter)
    {
        ShowStackPanel= true;
    }

}

在MVVM中StackPanel的可见性

2 个答案: