我试图创建一个简单的程序,您可以在其中将汽车添加到列表中并查看品牌模型和年份.在我的xaml主窗口中,我有3个文本框来收集用户的信息：

<TextBox Text="{Binding NewCar.Model}"/>
<TextBox Text="{Binding NewCar.Make}"/>
<TextBox Text="{Binding NewCar.Year}"/>

然后,用户单击“添加”按钮,该车应添加到列表中：

<Button Content="Add" Command="{Binding TouchCommand}" CommandParameter="{Binding NewCar}"/>

我已经验证了touch命令可以正常添加汽车,但是似乎存在根本问题,因为文本框未将输入文本的内容绑定到NewCar对象的各个属性,因为当我单击添加按钮时,参数为仍然为空.

这是add的execute方法：

    public void Execute(object parameter)
    {
        Car param = parameter as Car;

        if (param != null)
        {
            lib.List.Add(param);
            Console.WriteLine("{0} {1} {2}", param.Make, param.Model, param.Year);
        }
        else
        {
            Console.WriteLine("Param is null");
        }
    }

这是我的视图模型中的相关代码：

namespace CarApp
{

public class Carvm : INotifyPropertyChanged
{
    private CarLib carLibrary;
    private Car currentCar;
    private DeleteCommand rmCommand;
    private AddCommand touchCommand;
    private Car newCar;

    public Car NewCar
    {
        get { return newCar; }
        set
        {
            newCar = value;
            NotifyPropertyChanged("NewCar");
        }
    }

    public Car CurrentCar
    {
        get { return currentCar; }
        set
        {
            currentCar = value;
            NotifyPropertyChanged("CurrentCar");
        }
    }

    public CarLib CarLibrary
    {
        get { return carLibrary; }
        set
        { 
            carLibrary = value;
            NotifyPropertyChanged("CarLibrary");
        }
    }

    public DeleteCommand RMCommand
    {
        get { return rmCommand; }
        set { rmCommand = value; }
    }

    public AddCommand TouchCommand
    {
        get { return touchCommand; }
        set { touchCommand = value; }
    }

    public Carvm()
    {
        carLibrary = new CarLib();

        carLibrary.List.Add(new Car("chevy", "corvette", "2016"));
        carLibrary.List.Add(new Car("ford", "gt", "2016"));
        carLibrary.List.Add(new Car("bmw", "m3", "2005"));

        rmCommand = new DeleteCommand(carLibrary);
        touchCommand = new AddCommand(carLibrary);

    }

    public event PropertyChangedEventHandler PropertyChanged;

    protected void NotifyPropertyChanged(String info)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(this, new PropertyChangedEventArgs(info));
        }
    }
}
}

解决方法:

public Carvm()
{
    carLibrary = new CarLib();

    carLibrary.List.Add(new Car("chevy", "corvette", "2016"));
    carLibrary.List.Add(new Car("ford", "gt", "2016"));
    carLibrary.List.Add(new Car("bmw", "m3", "2005"));

    rmCommand = new DeleteCommand(carLibrary);
    touchCommand = new AddCommand(carLibrary);
    NewCar = new Car(); // this line is added

}