MVVMCROSS-將參數傳遞給ViewModel

Question

我正在嘗試將參數傳遞給引發“ MvvmCross.Platform.Exceptions.MvxException的子ViewModel構造函數：無法構造和初始化ViewModel ... MvxIoCResolveException：無法解析MyType類型的參數myParam的參數”。

MyChildViewModel.cs

public class MyChildViewModel : MvxViewModel
{
    private MyType _myParam;
    public MyType MyParam
    {
        get { return _myParam; }
        set
        {
            if (SetProperty(ref _myParam, value))
            {
                RaisePropertyChanged(() => MyParam);
            }
        }
    }

    public MyChildViewModel(MyType myParam)
    {
        _myParam = myParam;
    }

}

在我的父ViewModel中，我有：

public ICommand ShowDialogCommand { get; private set; }
ShowDialogCommand = new MvxCommand<MyType>(e => ShowViewModel<MyChildViewModel>(e));

家長活動電話：

ViewModel.ShowDialogCommand.Execute(VarOfMyType);

我顯然做錯了。 這是將數據傳遞給子ViewModel的遠程接受方法嗎？ 最佳做法是什么？

預先感謝您的寶貴時間。

Answer 1

如果您閱讀了文檔，則可以使用MvxNavigationService輕松傳遞對象： https ://www.mvvmcross.com/documentation/fundamentals/navigation

請注意，該文檔是針對MvvmCross 5.2的，該文檔當前在夜間發布，但適用於5.0及更高版本。

在您的ViewModel中，它可能類似於：

public class MyViewModel : MvxViewModel
{
    private readonly IMvxNavigationService _navigationService;
    public MyViewModel(IMvxNavigationService navigationService)
    {
        _navigationService = navigationService;
    }

    public override void Prepare()
    {
        //Do anything before navigating to the view
    }

    public async Task SomeMethod()
    {
        await _navigationService.Navigate<NextViewModel, MyObject>(new MyObject());
    }
}

public class NextViewModel : MvxViewModel<MyObject>
{
    public override void Prepare(MyObject parameter)
    {
        //Do anything before navigating to the view
        //Save the parameter to a property if you want to use it later
    }

    public override async Task Initialize()
    {
        //Do heavy work and data loading here
    }
}

Answer 2

在此網站上 ，他們的工作方式是（針對您的情況進行了修改和修改）：

public ICommand ShowDialogCommand { get; private set; }
ShowDialogCommand = new MvxCommand<MyType>(ShowMyVM);

private void ShowMyVM(MyType e)
{
    if (e != null)
        ShowViewModel<SingleClientViewModel>(e);
    else
    {
        //handle case where your parameter is null
    }
}