Question

我的主窗口ViewModel中有以下ICommand。

RelayCommand busyIndicatorCommand;

public ICommand BusyIndicatorCommand
{
    get
    {
        if (busyIndicatorCommand == null)
            busyIndicatorCommand = new RelayCommand(BusyIndicatorCommandExecute, CanBusyIndicatorCommand);
        return busyIndicatorCommand;
    }
}

在XAML中你有一个按钮时，从子视图调用这样的东西是一个简单的过程。

<Button Content="Press Me" 
        Command="{Binding DataContext.BusyIndicatorCommand, RelativeSource={RelativeSource AncestorType=Window}}"
        CommandParameter="{Binding EnableIndicator}"/>

我想做同样的事情，除了我的ViewModel并且没有按钮。我该怎么做？

[编辑]最终解决方案

创建了一个新的类项目

namespace Libs_SharedCommands
{    public class Commands
    {
        public enum CommandType
        {
            BusyIndicator
        }
        public static RoutedCommand cmd_BusyIndicator = new RoutedCommand();
    }
}

在我的用户控件视图模型中添加了对它的引用，并执行它。

namespace UserControls
{
    class UserControlViewModel
    {

        public UserControlViewModel()
        {
            setBusyIndicator(true);
            Task.Factory.StartNew(() =>
            {
                //Do stuff here
            })
            .ContinueWith(t =>
            {
                Application.Current.Dispatcher.Invoke(new Action(() => setBusyIndicator(false)));
            });
        }

        private void setBusyIndicator(bool enable)
        {
            Libs_SharedCommands.Commands.cmd_BusyIndicator.Execute(enable, null);
        }

    }
}

最后将RoutedCommand处理程序添加到我的主窗口View中，View窗口又调用主窗口ViewModel。对此非常满意，MVVM仍然完好无损。

namespace Application
{
    public partial class MainView
    {
        public MainView()
        {
            InitializeComponent();

            CommandBinding cbBusyIndicator = new CommandBinding(Libs_SharedCommands.Commands.cmd_BusyIndicator, BusyIndicator_MainNavCmdExecute, MainNavCmdCanExecute);
            this.CommandBindings.Add(cbBusyIndicator);
        }

        private void BusyIndicator_MainNavCmdExecute(object sender, ExecutedRoutedEventArgs e)
        {
            setCommand(Libs_SharedCommands.Commands.CommandType.BusyIndicator, e.Parameter);
        }
        private void MainNavCmdCanExecute(object sender, CanExecuteRoutedEventArgs e)
        {
            e.CanExecute = true;
        }

        private void setCommand(Libs_SharedCommands.Commands.CommandType view_type, object parameter)
        {
            var viewModel = (MainViewModel)DataContext;
            if (viewModel != null)
            {
                switch (view_type)
                {
                    case Libs_SharedCommands.Commands.CommandType.BusyIndicator:
                        viewModel.ShowBusyIndicator = Convert.ToBoolean(parameter);
                        break;
                    default:
                        break;
                }
            }
        }
    }
}

Answer 1

使用命令的Execute method：

BusyIndicatorCommand.Execute(EnableIndicator);

如何以编程方式发送命令

1 个答案: