无法从MVVM Light项目中的删除命令删除DataGrid中的行

Question

我设计了一个视图，用于从Datagrid UI获取用户想要的输入。 添加(+)按钮更好用意味着它一个接一个地添加行但是当我按下删除(X)按钮时它会抛出一个异常。其实我想通过单击删除按钮删除特定行。我怎么解决？

XMAL和GridView：

这是代码

 public class SaleViewModel : ViewModelBase, INotifyPropertyChanged
 {

    private ViewModelLocator _locator;
    public SaleViewModel():base()
    {
        _locator = new ViewModelLocator();
        _myObject = new ObservableCollection<Sale>();
        _Item = new Sale();
        Items = new ObservableCollection<Sale>();
        Items.Add(new Sale());
    }

    private RelayCommand _createNewRowCommand;
    public RelayCommand CreateNewRow
    {
        get { return _createNewRowCommand ?? (_createNewRowCommand = new RelayCommand(() => createNewRow())); }
    }

    void createNewRow()
    {
        Items.Add(new Sale());
    }

    private RelayCommand<Sale> _deleteRowCommand;
    public RelayCommand<Sale> DeleteRow
    {
        get { return _deleteRowCommand ?? (_deleteRowCommand = new RelayCommand<Sale>((p) => deleteRow(p))); }
    }

    void deleteRow(Sale p)
    {
            Items.Remove(p);
            Items = new ObservableCollection<Sale>(Items);
    }

    private RelayCommand _SaveItemCommand;
    public RelayCommand SaveItem
    {
        get { return _SaveItemCommand ?? (_SaveItemCommand = new RelayCommand(() => saveItem())); }
    }

    TestEntities3 context;
    void saveItem()
    {
        context = new TestEntities3(); ;

            context.Sales.Add(Item);
            context.SaveChanges();
    }

    private ObservableCollection<Sale> _myObject;

    public ObservableCollection<Sale> Items
    {
        get { return _myObject; }
        set
        {
            _myObject = value;
            base.RaisePropertyChanged("Items");
        }
    }
    private Sale _Item;

    public Sale Item
    {
        get { return _Item; }
        set { _Item = value; base.RaisePropertyChanged("Item"); }
    }

    public int? Qty
    {
        get { return _Item.Qty; }
        set { _Item.Qty = value; base.RaisePropertyChanged("Qty"); }
    }
 }

请告诉我我在哪里做错了？

Answer 1

试试这个

if(p!=null)
{
  Items.Remove(p);
  .......
}