Question

我有一个prism unity应用程序，如何在viewmodel属性中更改一个子类？

如何在viewmodel中实现具有复杂对象的CanExecute？

MODEL

public class WardModel : BindableBase
{
    private string _Id;

    public string Id
    {
        get { return _Id; }
        set { SetProperty(ref _Id, value); }
    }
}

视图模型

public class ucAddViewModel : BindableBase
{
    private readonly IUnityContainer _unityContainer;
    private readonly IRegionManager _regionManager;

    private WardModel _Ward;

    public WardModel Ward
    {
        get
        {
            return _Ward;
        }
        set
        {
            SetProperty(ref _Ward, value);

            CanSaveExecute = Ward.Id != null && Ward.Id != string.Empty;
        }
    }
}

XAML

<TextBox Text="{Binding Ward.Id, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Height="30" VerticalAlignment="Top" Margin="0,0,0,10"></TextBox>

Answer 1

Execute和CanExecute方法与命令一起使用，不能在访问器中使用它们。如果您想确保您的Id没有错误的值，只需将您的验证规则放入Model类。

 public class WardModel : BindableBase
    {
        private string _Id;
        public string Id
        {
            get { return _Id; }
            set
            {
                if(!string.IsNullOrWhiteSpace(value)) SetProperty(ref _Id, value);
            }
        }
    }

Answer 2

假设您想在viewModel的属性发生更改后刷新命令。

型号：

public class MyModel : BindableBase
{
   private string Name _name;
   public Name 
   {
     get { return _name; }
     set { SetProperty(ref _name, value); }
   }
}

视图模型：

public class MyViewModel : BindableBase
{
   private DelegateCommand _myCommand;
   public DelegateCommand MyCommand => _myCommand ?? (_myCommand = new DelegateCommand(Execute, CanExecute));

   //your method that will be executed
   private void Execute()
   {
       //Do sth.
   }

   //will be triggered through MyCommand.RaiseCanExecuteChanged()
   private bool CanExecute()
   {
       //you validating logic, e.g.
       return MyComplexObject != null;
   }

   private MyModel _myComplexObject;
   public MyModel MyComplexObject
   {
      get { return _myComplexObject; }
      set 
      {
          SetProperty(ref _myComplexObject, value);
          //Trigger the CanExecuteChanged Event
          MyCommand.RaiseCanExecuteChanged();
      }
   }
}

Prism Unity - WPF在ViewModel中绑定子类

2 个答案: