在 Xamarin MvvmCross 中将对象从父级传递给子级

Question

我有一个 SlideListViewModel：

public class SlideListViewModel : MvxViewModel
{
    private readonly IServerClient _serverClient;
    private ICollection<SlideListItemViewModel> _slides;
    private IMapperService _mapper;

    public ICollection<SlideListItemViewModel> Slides { get => _slides; set => SetProperty(ref _slides, value); }

    public SlideListViewModel(IServerClient serverClient, IMapperService mapper)
    {
        _serverClient = serverClient;
        _mapper = mapper;
    }

    public override async Task Initialize()
    {
        await base.Initialize();
        Slides = _mapper.Map<ICollection<SlideListItemViewModel>>(await _serverClient.GetSlideList());
    }
}

我有一个 SlideListItemViewModel：

public class SlideListItemViewModel : MvxViewModel
{
    private long _id;
    private string _title;

    public long Id { get => _id; set => SetProperty(ref _id, value); }

    public string Title { get => _title; set => SetProperty(ref _title, value); }

    public IMvxCommand DeleteCommand => new MvxCommand<IServerClient>(DeleteCommandHandler);

    public async void DeleteCommandHandler(IServerClient serverClient)
    {
        var delete = await UserDialogs.Instance.ConfirmAsync(new ConfirmConfig
        {
            Title = "Delete slide",
            Message = "Are you sure you want to delete this slide?",
            OkText = "Yes",
            CancelText = "No"
        });

        if (!delete)
            return;

        //Here I should user my serverClient
    }
}

是否可以从SlideListViewModel 向接口_serverClient 传递命令？我尝试在 slidelistitemviewmodel.axml 中绑定，但什么也没发生...

 <Button
    local:MvxBind="Click DeleteCommand, CommandParameter=_serverClient"
    style="@style/ButtonSlide"
    android:layout_width="wrap_content"
    android:layout_height="match_parent"
    android:text="Delete" />

有人可以帮我吗？？？

Answer 1

您需要在 SlideListItemViewModel 中使用它。 SlideListItemViewModel.xaml 无权访问 SlideListViewModel。 不必费心将其设为命令参数，只需在创建项目时从 SlideListViewModel 传入即可。在 SlideListItemViewModel.cs 中添加属性：

public class SlideListItemViewModel : MvxViewModel
{
    private long _id;
    private string _title;
    private IServerClient _serverClient;

    public long Id { get => _id; set => SetProperty(ref _id, value); }

    public string Title { get => _title; set => SetProperty(ref _title, value); }

    public IServerClient ServerClient {get => _serverClient; set => SetProperty(ref _serverClient, value; }

    public IMvxCommand DeleteCommand => new MvxCommand(DeleteCommandHandler);

    public async void DeleteCommandHandler()
    {
        var delete = await UserDialogs.Instance.ConfirmAsync(new ConfirmConfig
        {
            Title = "Delete slide",
            Message = "Are you sure you want to delete this slide?",
            OkText = "Yes",
            CancelText = "No"
        });

        if (!delete)
            return;

        //Here I should user my serverClient
    }
}

在 SlideListViewModel.cs 中创建时传递它：

public override async Task Initialize()
{
    await base.Initialize();
    Slides = _mapper.Map<ICollection<SlideListItemViewModel>>(await _serverClient.GetSlideList());
    foreach(var slide in Slides)
    {
        slide.ServerClient = _serverClient;
    }
}

并将其从 SlideListItemViewModel.xaml 中的绑定中取出：

local:MvxBind="Click DeleteCommand"