小编典典

如何将WPF按钮绑定到ViewModelBase中的命令?

c#

我有一个AttributeView包含各种属性的视图。还有一个按钮,当按下该按钮时,应将默认值设置为属性。我还有一个ViewModelBase类,它是我拥有的所有ViewModel的基类。问题是我似乎无法使用WPF将按钮绑定到命令。

我已经尝试过了,但是它什么也没做:

<Button Command="{Binding DataInitialization}" Content="{x:Static localProperties:Resources.BtnReinitializeData}"></Button>

该命令的定义ViewModelBase如下:

public CommandBase DataInitialization { get; protected set; }

在应用程序启动时,将为命令创建一个新实例:

DataInitialization = new DataInitializationCommand()

但是,WPF绑定似乎无法“找到”命令(按按钮不会执行任何操作)。当前视图中使用的ViewModel源自ViewModelBase。还有什么可以尝试的(我对WPF还是很陌生,所以这可能是一个非常简单的问题)?


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2020-05-19

共1个答案

小编典典

 <Grid >
    <Grid.ColumnDefinitions>
        <ColumnDefinition Width="*"/>
    </Grid.ColumnDefinitions>
    <Button Command="{Binding ClickCommand}" Width="100" Height="100" Content="wefwfwef"/>
</Grid>

窗口后面的代码:

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();
        DataContext = new ViewModelBase();
    }
}

ViewModel:

public class ViewModelBase
{
    private ICommand _clickCommand;
    public ICommand ClickCommand
    {
        get
        {
            return _clickCommand ?? (_clickCommand = new CommandHandler(() => MyAction(), ()=> CanExecute));
        }
    }
     public bool CanExecute
     {
        get
        {
            // check if executing is allowed, i.e., validate, check if a process is running, etc. 
            return true/false;
        }
     }

    public void MyAction()
    {

    }
}

命令处理程序:

 public class CommandHandler : ICommand
{
    private Action _action;
    private Func<bool> _canExecute;

    /// <summary>
    /// Creates instance of the command handler
    /// </summary>
    /// <param name="action">Action to be executed by the command</param>
    /// <param name="canExecute">A bolean property to containing current permissions to execute the command</param>
    public CommandHandler(Action action, Func<bool> canExecute)
    {
        _action = action;
        _canExecute = canExecute;
    }

    /// <summary>
    /// Wires CanExecuteChanged event 
    /// </summary>
    public event EventHandler CanExecuteChanged
    {
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }
    }

    /// <summary>
    /// Forcess checking if execute is allowed
    /// </summary>
    /// <param name="parameter"></param>
    /// <returns></returns>
    public bool CanExecute(object parameter)
    {
        return _canExecute.Invoke();
    }

    public void Execute(object parameter)
    {
        _action();
    }
}

我希望这会给你这个主意。

2020-05-19