通知集合跨视图模型更改

Question

我有一个场景，主窗口具有内容控制，我通过它切换特定视图的用户控制并分别具有视图模型

在我的一个用户控件中有另一个用户控件。两者都有一个视图模型

<UserControl DataContext="ViewModel1">

<Grid>

 <ListView ItemsSource="{Binding TimeSlotCollection}"  <!--This Collection is in ViewModel 1-->
                  ">
  </ListView>

  <UserControl DataContext="ViewModel2">
      <DataGrid x:Name="DataGrid" 
              CanUserAddRows="True"                 
              ItemsSource="{Binding TimeSlotCollection,Mode=TwoWay,
              UpdateSourceTrigger=PropertyChanged}"/>  <!--This Collection is in ViewModel 2-->
 </Grid>

</UserControl>  

我想在视图模型 2 集合发生更改时通知视图模型 1 集合

MyViewModel 1

    private ObservableCollection<AttendanceTimeSlotModel> _timeslotCollection;

    public ObservableCollection<AttendanceTimeSlotModel> TimeSlotCollection
    {
        get { return _timeslotCollection; }
        set
        {
            Set(TimeSlotCollectionPropertyName, ref _timeslotCollection, value);
        }
    }



    public const string EmployeesCollectionPropertyName = "Employees";

    private ObservableCollection<EmployeeModel> _employees;

    public ObservableCollection<EmployeeModel> Employees
    {
        get { return _employees; }
        set
        {
            Set(EmployeesCollectionPropertyName, ref _employees, value);
        }
    }


    public const string IsBusyPropertyName = "IsBusy";

    private bool _isBusy = false;
    public bool IsBusy
    {
        get
        {
            return _isBusy;
        }
        set
        {
            Set(IsBusyPropertyName, ref _isBusy, value);
        }
    }

MyViewModel 2

    public const string AttendanceTimeSlotCollectionPropertyName = "TimeSlotCollection";

    private ObservableCollection<AttendanceTimeSlotModel> _timeSlotCollection = null;

    public ObservableCollection<AttendanceTimeSlotModel> TimeSlotCollection
    {
        get
        {
            return _timeSlotCollection;
        }
        set
        {
            Set(AttendanceTimeSlotCollectionPropertyName, ref _timeSlotCollection, value);
        }
    } 

    /// What i trying 
     public void AddNewTimeSlot(AttendanceTimeSlotModel timeSlot)
    {


        _designdataService.InsertTimeSlot(timeSlot);
        var Vm = SimpleIoc.Default.GetInstance<ViewModels.AssignTimeSlotViewModel>();
        RaisePropertyChanged(Vm.TimeSlotCollection);
    }

当我在 View-model 2 中的集合更新时我想要在 View-model 1 中通知我想要实现的目标。

Answer 1

在使用 MVVM 时，我喜欢只对一个视图使用一个视图模型。如果您只是将您的内部UserControl 视为其父UserControl 的一部分，那么您只需要一个视图模型。尝试像这样重新排列您的代码：

<UserControl DataContext="ViewModel1">
    <Grid>    
        <ListView ItemsSource="{Binding TimeSlotCollection}" />
        <UserControl DataContext="{Binding TimeSlotCollection}">
            ... 
            <!-- Then inside the inner control -->
            <DataGrid x:Name="DataGrid" ItemsSource="{Binding}" ... />
            ...
        </UserControl>
    </Grid>
</UserControl> 

这样，您只需要在一个视图模型中管理一个集合，大部分问题就会消失。