不确定我在尝试创建/添加此命令时做错了什么：

Question

XAML 按钮：

<Button Content="Test Connection" Name="btnTestConnection" Command="{Binding Path=TestCommand}" CommandParameter="{Binding ElementName=someObject}"/>

查看模型：

public ICommand TestCommand
{
    get;
    internal set;
}

private bool CanExecuteTestCommand()
{
    return !String.IsNullOrEmpty(txtControl);
}

private void CreateTestCommand()
{
    TestCommand = new TestCommand(TestExecute);
}

public void TestExecute(object parameter)
{
    //do stuff with parameter

    obj.TestConnection(parameter);
}

我想指出，CreateTestCommand() 在我的 VM 构造函数中被调用。

最后，我对TestCommand的实现：

class TestCommand : ICommand
{
   private Action<object> execute;

   private Predicate<object> canExecute;

   private event EventHandler CanExecuteChangedInternal;

   public TestCommand(Action<object> execute)
       : this(execute, DefaultCanExecute)
   {
   }

   public TestCommand(Action<object> execute, Predicate<object> canExecute)
   {
       if (execute == null)
       {
           throw new ArgumentNullException("execute");
       }

       if (canExecute == null)
       {
           throw new ArgumentNullException("canExecute");
       }

       this.execute = execute;
       this.canExecute = canExecute;
   }

   public event EventHandler CanExecuteChanged
   {
       add
       {
           CommandManager.RequerySuggested += value;
           this.CanExecuteChangedInternal += value;
       }

       remove
       {
           CommandManager.RequerySuggested -= value;
           this.CanExecuteChangedInternal -= value;
       }
   }

   public bool CanExecute(object parameter)
   {
       return this.canExecute != null && this.canExecute(parameter);
   }

   public void Execute(object parameter)
   {
       this.execute(parameter);
   }

   public void OnCanExecuteChanged()
   {
       EventHandler handler = this.CanExecuteChangedInternal;
       if (handler != null)
       {
           handler.Invoke(this, EventArgs.Empty);
       }
   }

   public void Destroy()
   {
       this.canExecute = _ => false;
       this.execute = _ => { return; };
   }

   private static bool DefaultCanExecute(object parameter)
   {
       return true;
   }
}

我在CreateTestCommand 中设置了断点，看起来配置正确：

但是当我点击btnTestConnection 时，什么也没有发生。我的视图模型中的TestExecute 没有被调用（它在实际模型上调用TestConnection）。我一定是错过了什么，但我一生都无法弄清楚是什么......

编辑包括我的视图模型的其余部分；

class FormProcessorViewModel
{
    FormProcessorModel obj;

    public FormProcessorViewModel()
    {
        obj = new FormProcessorModel();
        CreateTestCommand();
    }

    public FormProcessorViewModel(string server, string database, string username, bool specifyDateRange, DateTime startDate, DateTime endDate, string operation, string preprocessed, string processed, string failed) :this()
    {
        txtServer = server;
        txtDatabase = database;
        txtUsername = username;
        chkSpecifyDateRange = specifyDateRange;
        dpStartDate = startDate;
        dpEndDate = endDate;
        txtOperation = operation;
        txtPreprocessed = preprocessed;
        txtProcessed = processed;
        txtFailed = failed;
    }

    public ICommand TestCmd
    {
        get;
        internal set;
    }

    private bool CanExecuteTestCommand()
    {
        return !String.IsNullOrEmpty(txtUsername);
    }

    private void CreateTestCommand()
    {
        TestCmd = new TestCommand(TestExecute);
    }

    private void TestExecute(object parameter)
    {
        var passwordBox = parameter as PasswordBox;
        var password = passwordBox.Password;

        obj.TestConnection(password);
    }

}

我省略了在第二个构造函数中设置的所有属性，只是因为它们除了引用模型对象上的相应值之外并没有真正做任何事情。

Answer 1

编辑

查看模型

class ViewModel : INotifyPropertyChanged
{


    private string _test;

    public string TestValue
    {
        get { return _test; }
        set { _test = value; RaisePropertyChanged("TestValue"); }
    }

    public ICommand MyCommand { get; internal set; }


    public ViewModel()
    {
        TestValue = "Test";
        CreateTestCommand();
    }

    private void CreateTestCommand()
    {
        MyCommand = new TestCommand(ExecuteButton);
    }

    private void ExecuteButton(object obj)
    {
        TestValue = "Cool";
    }

    public event PropertyChangedEventHandler PropertyChanged;

    void RaisePropertyChanged(string propName)
    {
        var pc = PropertyChanged;
        if (pc != null)
        {
            pc(this, new PropertyChangedEventArgs(propName));
        }
    }
}

Xaml

<Button Content="{Binding TestValue}" Command="{Binding Path=MyCommand}" CommandParameter="{Binding RelativeSource={RelativeSource Self}}"/>

Xaml 代码。

public MainWindow()
{
    InitializeComponent();
    this.DataContext = new ViewModel();
}