子视图模型更新时如何更新父视图模型

在我的第一个视图模型（重命名为MainViewModel）中，我有一个ActionViewModels列表。在我的xaml中，我有一个绑定到列表的列表框，在该列表框中，我有一个模板，该模板绑定到ActionViewModel的属性。

到目前为止，一切都很好。当选择我导航到ActionViewModel并与它通过该ID的listItems中的一个。ActionViewModel从内存中的静态列表中检索信息，MainViewModel也从该列表中检索信息以创建actionviewmodels列表。

到目前为止还算不错，我可以编辑属性，所有绑定都可以正常工作，我也很高兴。通过单击保存按钮，信息将被收集并存储在静态列表中。当我按下“后退”按钮时，我返回到列表，但是不幸的是，显示的值仍然相同，是否可以通过某种方式发送命令以重新加载列表中的项目？要传递完整的ViewModel作为对新ActionViewModel的引用？还是告诉父级“您列表中的此视图模型已更新”的某些属性？

我敢肯定，上面的文字有点让人困惑，所以这里有一些代码可以澄清一下（希望如此）

MainViewModel.cs

private List<ActionViewModel> _actionViewModels;
public List<ActionViewModel> ActionViewModels
{
    get { return _actionViewModels; }
    set { _actionViewModels = value; RaisePropertyChanged(() => ActionViewModels); }
}


private Cirrious.MvvmCross.ViewModels.MvxCommand<int> _navigateToAction;
public System.Windows.Input.ICommand NavigateToAction
{
    get
    {
        _navigateToAction = _navigateToAction ?? new Cirrious.MvvmCross.ViewModels.MvxCommand<int>((action) => NavigateToTheDesiredAction(action));
        return _navigateToAction;
    }
}

private void NavigateToTheDesiredAction(int action)
{
    ShowViewModel<ActionViewModel>(new { id = action });
}

// Get DTOs from server or from cache and fill the list of ActionViewModels
public async Task Load()
{
    ActionService actionService = new ActionService();

    List<ActionViewModel> actionViewModels = new List<ActionViewModel>();

    MyActions = await actionService.GetMyActions();
    foreach (ActionDTO action in MyActions)
    {
        ActionViewModel actionViewModel = new ActionViewModel();
        await actionViewModel.Load(action.id);
        actionViewModels.Add(actionViewModel);
    }

    ActionViewModels = actionViewModels;
}

ActionViewModel.cs

public int ID
{
    get { return TheAction.id; }
    set { TheAction.id = value; RaisePropertyChanged(() => ID); }
}

public string Title
{
    get { return TheAction.Title; }
    set { TheAction.Title = value; RaisePropertyChanged(() => Title); }
}

public async Task Load(int actionId)
{
    ActionDTO TheAction = await actionService.GetAction(actionId);
    this.ID = TheAction.id;
    this.Title = TheAction.Title;
}

private Cirrious.MvvmCross.ViewModels.MvxCommand _save;
public System.Windows.Input.ICommand Save
{
    get
    {
        _save = _save ?? new Cirrious.MvvmCross.ViewModels.MvxCommand(PreSaveModel);
        return _save;
    }
}

private void PreSaveModel()
{
    SaveModel();
}

private async Task SaveModel()
{
    ValidationDTO result = await actionService.SaveAction(TheAction);
}

ActionService.cs

public static List<ActionDTO> AllActions = new List<ActionDTO>();

public async Task<ActionDTO> GetAction(int actionId)
{
    ActionDTO action = AllActions.FirstOrDefault(a => a.id == actionId);
    if (action == null)
    {
        int tempActionId = await LoadAction(actionId);
        if (tempActionId > 0)
            return await GetAction(actionId);
        else
            return new ActionDTO() { Error = new ValidationDTO(false, "Failed to load the action with id " + actionId, ErrorCode.InvalidActionId) };
    }
    return action;
}

private async Task<int> LoadAction(int actionId)
{
    ActionDTO action = await webservice.GetAction(actionId);
    AllActions.Add(action);
    return action.id;
}

public async Task<ValidationDTO> SaveAction(ActionDTO action)
{
    List<ActionDTO> currentList = AllActions;
    ActionDTO removeActionFromList = currentList.FirstOrDefault(a => a.id == action.id);
    if (removeActionFromList != null)
        currentList.Remove(removeActionFromList);

    currentList.Add(action);
    AllActions = currentList;
    return await webservice.SaveAction(action);
}