更新ViewModel并查看

Question

有一个MainWindow，我通过单击菜单在UserControls之间导航，它可以正常工作。

我在Prism中使用以下模式：

https://rachel53461.wordpress.com/2011/05/08/simplemvvmexample/

保存信息后，我需要更新ViewModel， 我更新它但View不更新。 我该如何解决？

的 MainViewModel

    public class AdminMenuViewModel : ObservableObject, IPageViewModel
    {
        protected readonly IEventAggregator _eventAggregator;

        public AdminMenuViewModel(IEventAggregator eventAggregator) 
        { 
            PageViewModels.Add(new FoodSupplierViewModel());
            PageViewModels.Add(new ProductViewModel());
            PageViewModels.Add(new UnitViewModel());
            PageViewModels.Add(new PriceViewModel());

            this._eventAggregator = eventAggregator;
            this._eventAggregator.GetEvent<UpdateProduct>().Subscribe(UpdateProduct);

            // Set starting page
            CurrentUserControl = PageViewModels[0];
        }

        public string Name
        {
            get
            {
                return "Admin";
            }
        }

        private List<IUserContentViewModel> _pageViewModels;
        public List<IUserContentViewModel> PageViewModels
        {
            get
            {
                if (_pageViewModels == null)
                    _pageViewModels = new List<IUserContentViewModel>();

                return _pageViewModels;
            }
        }

        private void UpdateProduct()
        {
            PageViewModels[1] = new ProductViewModel(); //I update the ViewModel here
        }

        private void ChangeViewModel(IUserContentViewModel viewModel)
        {
            if (!PageViewModels.Contains(viewModel))
                PageViewModels.Add(viewModel);

            CurrentUserControl = PageViewModels
                .FirstOrDefault(vm => vm == viewModel);
        }



        private ICommand _changePageCommand;

        public ICommand ChangePageCommand
        {
            get
            {
                if (_changePageCommand == null)
                {
                    _changePageCommand = new RelayCommand(
                        p => ChangeViewModel((IUserContentViewModel)p),
                        p => p is IUserContentViewModel);
                }
                return _changePageCommand;
            }
        }
    }

的的MainView

<UserControl.Resources>

        <DataTemplate DataType="{x:Type avm:FoodSupplierViewModel}">
            <av:FoodSupplierView/>
        </DataTemplate>
        <DataTemplate DataType="{x:Type avm:ProductViewModel}">
            <av:ProductView/>
        </DataTemplate>
        <DataTemplate DataType="{x:Type avm:UnitViewModel}">
            <av:UnitView/>
        </DataTemplate>
        <DataTemplate DataType="{x:Type avm:PriceViewModel}">
            <av:PriceView/>
        </DataTemplate>

    </UserControl.Resources>

    <Grid  Margin="5" >
       <Border BorderThickness="1" BorderBrush="Black" CornerRadius="10">
            <Grid>
                <Border Name="mask" Background="White" CornerRadius="9"/>
                <StackPanel>
                    <Menu Grid.Row="0" Height="58">
                        <MenuItem Header="General" FontSize="20" Height="38" Margin="10" Foreground="SteelBlue">
                            <ItemsControl ItemsSource="{Binding PageViewModels}" Width="168" >
                                <ItemsControl.ItemsPanel>
                                    <ItemsPanelTemplate>
                                        <StackPanel Orientation="Vertical"/>
                                    </ItemsPanelTemplate>
                                </ItemsControl.ItemsPanel>
                                <ItemsControl.ItemTemplate>
                                    <DataTemplate>
                                        <TextBlock>
                                            <Hyperlink Command="{Binding DataContext.ChangePageCommand, RelativeSource={RelativeSource AncestorType={x:Type UserControl}}}"  
                                                       CommandParameter="{Binding}" TextDecorations="{x:Null}">
                                                <InlineUIContainer>
                                                    <TextBlock Text="{Binding Name}" FontSize="18"/>
                                                </InlineUIContainer>
                                            </Hyperlink>
                                        </TextBlock>
                                    </DataTemplate>
                                </ItemsControl.ItemTemplate>
                            </ItemsControl>
                        </MenuItem>
                   </Menu>
                </StackPanel>
            </Grid>
        </Border>
        <Border Grid.Row="1" BorderThickness="1" CornerRadius="8" >
            <ContentControl Content="{Binding CurrentUserControl}" Margin="0,0,-1,0"/>
        </Border>
    </Grid>

Answer 1

如果要在该集合中添加/删除时通知，请使用ObservableCollection<T>代替List<T>，如果项目中有更新，请使用OnPropertyChanged