Wpf 多个嵌套用户控件与 MvvmCross

Question

我是 MvvmCross 的新手，但我在 mvvm 工作了一段时间。我知道如何使用嵌套的用户控件组合用户控件。现在使用 mvvmcross 我不得不在另一个用户控件中显示两个或更多用户控件。除了 MvvmCross，我不使用任何其他框架。我的 Rootview 看起来像这样：

`<views:MvxWpfView
    x:Class="MvvmCrossTest.Wpf.Views.RootView"
    xmlns:views="clr-namespace:MvvmCross.Platforms.Wpf.Views;assembly=MvvmCross.Platforms.Wpf"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
    mc:Ignorable="d" 
    d:DesignHeight="450" d:DesignWidth="800">

    <DockPanel>  
        <TextBlock Text="Root" DockPanel.Dock="Top"/>
        <ContentControl x:Name="MainMenuVM" Content="{Binding MainMenuVM}" DockPanel.Dock="Top" />
    </DockPanel>
</views:MvxWpfView>`

相应的 ViewModel 如下所示：

using MvvmCross.Commands;
using MvvmCross.Logging;
using MvvmCross.Navigation;
using MvvmCross.ViewModels;

namespace MvvmCrossTest.Core.ViewModels
{
    public class RootViewModel: MvxNavigationViewModel
    {
        private readonly IMvxViewModelLoader _mvxViewModelLoader;
        public RootViewModel(IMvxLogProvider logProvider, IMvxNavigationService navigationService, IMvxViewModelLoader mvxViewModelLoader) : base(logProvider, navigationService)
        {
            _mvxViewModelLoader = mvxViewModelLoader;
            ShowMainMenu();
        }

        private MainMenuViewModel _mainMenuVM;

        public MainMenuViewModel MainMenuVM
        {
            get { return _mainMenuVM; }
            set 
            {
                SetProperty(ref _mainMenuVM, value);
                RaisePropertyChanged(() => MainMenuVM);
            }
        }

         public MvxCommand ShowMainMenuCommand { get; set; }

        public void ShowMainMenu()
        {
            MainMenuVM = (MainMenuViewModel)_mvxViewModelLoader.LoadViewModel(MvxViewModelRequest.GetDefaultRequest(typeof(MainMenuViewModel)), null, null);
        }
    }
}

我想在内容控件中显示的简化视图如下所示：

<views:MvxWpfView
    x:Class="MvvmCrossTest.Wpf.Views.MainMenuView"
    xmlns:views="clr-namespace:MvvmCross.Platforms.Wpf.Views;assembly=MvvmCross.Platforms.Wpf"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
    mc:Ignorable="d"
    Background="Aqua"
    d:DesignHeight="450" d:DesignWidth="800">
    <Grid>
            
    </Grid>
</views:MvxWpfView>

还有对应的ViewModel。

using MvvmCross.Logging;
using MvvmCross.Navigation;
using MvvmCross.ViewModels;

namespace MvvmCrossTest.Core.ViewModels
{
    public class MainMenuViewModel : MvxNavigationViewModel
    {
        public MainMenuViewModel(IMvxLogProvider logProvider, IMvxNavigationService navigationService) : base(logProvider, navigationService)
        {

        }
    }
}

而不是 View/ViewModel 我看到了一条文字，上面写着“MvvmCrossTest.Core.ViewModels.MainMenuViewModel”。

我不想使用 Xamarin！

Answer 1

it seems that MvvmCross is wiring up Views and ViewModels automatically

我对 MvvmCross 一无所知，但要“自动”工作，应该有一个协议和规则，例如属性或匹配名称（xViewModel <-> xView）。目前我看不到 MainMenuViewModel 与 views:MvxWpfView.

有什么联系

随便你看到什么

I see a text that says "MvvmCrossTest.Core.ViewModels.MainMenuViewModel"

是由于缺少数据模板而试图将非控件可视化为文本的视图。

只需添加数据模板即可轻松修复

<DataTemplate DataType="{x:Type local:MainMenuViewModel}">
    <views:MvxWpfView />
</DataTemplate>

某处（例如进入 views:MvxWpfView.Resources），将显示该视图。

Answer 2

我创建了一个 project 向您展示了一些基础知识。

简单

您可以找到示例 here。

RootView;

<views:MvxWpfView xmlns:local="clr-namespace:SomeProject.Views" ...>
     <Grid>
           <Label Content="Hello from RootView" />
           <local:NestedView />    
     </Grid>
</views:MvxWpfView>

NestedView;

<views:MvxWpfView ...>
     <Grid>
           <Label Content="Hello from NestedView" />  
     </Grid>
</views:MvxWpfView>

扩展（自定义演示者）

使用此自定义 wpf 演示器，您可以在容器中指定视图时轻松导航到视图。这样，您可以在使用 mvvmcross 导航服务时从视图模型关闭和打开视图。

我从另一个 project. You can find the whole implementation in my sample project here.

复制了这个

RootView;

<views:MvxWpfView ...>
      <Grid>
           <Label Content="Hello" />
           <ItemsControl region:MvxContainer.Id="RootViewRegion"/>    
      </Grid>
</views:MvxWpfView>

后面的RootView代码；

[MvxContentPagePresentation(WrapInNavigationPage = true, NoHistory = false)]
public partial class RootView: MvxWpfView<RootViewModel>
{
     public RootView()
     {
          InitializeComponent();
     }
}

RootViewModel;

public class RootViewModel: MvxNavigationViewModel
{
      private readonly IMvxNavigationService _navigationService;

      public IMvxAsyncCommand ShowNestedViewModelCommand { get; protected set; }

      public RootViewModel(IMvxLogProvider logProvider, IMvxNavigationService navigationService) : base(logProvider, navigationService)
      {
            this._navigationService = navigationService;
    
            // navigate to nested view
            this.ShowNestedViewModelCommand = new MvxAsyncCommand(() => this._navigationService.Navigate<NestedViewModel>());

            ShowNestedViewModelCommand.Execute();
      }
}

后面的NestedView代码；

[MvxWpfPresenter("RootViewRegion", mvxViewPosition.NewOrExsist)]
public partial class NestedView : MvxWpfView<NestedViewModel>
{
    public NestedView()
    {
        InitializeComponent();
    }
}

很高兴知道

当您遇到导航和视图模型连接问题时，请使用后面的代码。它加载特定视图的视图模型；

[MvxContentPagePresentation(WrapInNavigationPage = true, NoHistory = false)]
public partial class SomeView : MvxWpfView<ViewModels.SomeViewModel>
{
    public SomeView()
    {
         InitializeComponent();
    
         if (!(ViewModel is ViewModels.SomeViewModel))
         {
              if (Mvx.IoCProvider.TryResolve<ViewModels.SomeViewModel>(out var someViewModel))
              {
                   ViewModel = someViewModel;
                   return;
              }
    
              var _viewModelLoader = Mvx.IoCProvider.Resolve<IMvxViewModelLoader>();
              var request = new MvxViewModelInstanceRequest(typeof(ViewModels.SomeViewModel));
              request.ViewModelInstance = _viewModelLoader.LoadViewModel(request, null);
              ViewModel = request.ViewModelInstance as ViewModels.SomeViewModel;
    
              Mvx.IoCProvider.RegisterSingleton<ViewModels.SomeViewModel>(ViewModel);
         }
    }
}

Wpf 多个嵌套用户控件与 MvvmCross

Wpf Multiple nested Usercontrols with MvvmCross

c#

wpf

mvvm

mvvmcross

简单

扩展（自定义演示者）

很高兴知道