c# - [Catel]如何将带有构造函数参数的ViewModel传递给TabServiceExtensions方法？

因此，上周我才刚开始使用Catel，但是我无法让选项卡式界面正常工作。我一直在使用以下资源，将选项卡式界面用于MVVM(https://catelproject.atlassian.net/wiki/display/CTL/Using+a+tabbed+interface+with+MVVM#UsingatabbedinterfacewithMVVM-CreatingClosableTabItem):

我有一个MainWindow(catel:Window)，其中包含带有xmlns:controls =“clr-namespace:AutoProgram.UI.Controls”的TabControl:

<Border Background="#50FFFFFF" BorderBrush="{StaticResource WindowFrameBrush}" BorderThickness="5" Margin="-6" Padding="0">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="30" />
            <RowDefinition />
            <RowDefinition />
        </Grid.RowDefinitions>
        <Border Grid.Row="0" Grid.Column="0" Background="{StaticResource WindowFrameBrush}" HorizontalAlignment="Stretch" VerticalAlignment="Stretch" CornerRadius="0,0,0,0" Margin="0" Padding="0">
            <Grid>
                <TextBlock Foreground="White" FontWeight="Bold" VerticalAlignment="Center" Margin="10,2,10,2" Text="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType={x:Type Window}}, Path=Title}"/>
                <Button Content="X" HorizontalAlignment="Right" VerticalAlignment="Center" Margin="1" FontSize="7" Width="15" Height="15" Padding="0" Command="ApplicationCommands.Close"/>
            </Grid>
        </Border>
        <catel:StackGrid Grid.Row="1" Grid.Column="0">
            <catel:StackGrid.RowDefinitions>
                <RowDefinition Height="Auto" />
                <RowDefinition Height="Auto" />
            </catel:StackGrid.RowDefinitions>
            <catel:StackGrid.ColumnDefinitions>
                <ColumnDefinition Width="*" />
            </catel:StackGrid.ColumnDefinitions>

            <ItemsControl x:Name="ItemsControlAutomators" Grid.Row="0" Grid.Column="0" ItemsSource="{Binding Automators}">
                <ItemsControl.ItemsPanel>
                    <ItemsPanelTemplate>
                        <UniformGrid Columns="3" />
                    </ItemsPanelTemplate>
                </ItemsControl.ItemsPanel>
                <ItemsControl.ItemTemplate>
                    <DataTemplate>
                        <Button x:Name="Button" Content="{Binding Automator.Name, Mode=OneWay}" Command="{Binding ElementName=ItemsControlAutomators, Path=DataContext.RunAutomator}" CommandParameter="{Binding}"></Button>
                    </DataTemplate>
                </ItemsControl.ItemTemplate>
            </ItemsControl>
        </catel:StackGrid>

        <catel:TabControl x:Name="TabControlAutomators" Grid.Row="2" Grid.Column="0" Margin="-2" LoadTabItems="LazyLoading">
            <TabControl.ItemTemplate>
                <DataTemplate>
                    <controls:ClosableTabItem Title="{Binding ViewModel.Title}" CanClose="{Binding CanClose}" />
                </DataTemplate>
            </TabControl.ItemTemplate>

            <TabControl.ContentTemplate>
                <DataTemplate>
                    <ContentControl Content="{Binding ViewModel, Converter={catel:ViewModelToViewConverter}}" />
                </DataTemplate>
            </TabControl.ContentTemplate>
        </catel:TabControl>
    </Grid>
</Border>

相关MainWindow.xaml.cs

public partial class MainWindow
{
    public MainWindow()
    {
        InitializeComponent();

        var serviceLocator = this.GetServiceLocator();
        var tabService = serviceLocator.ResolveType<ITabService>() as TabService;

        tabService?.SetTabControl(TabControlAutomators);
    }
}

相关的MainWindowViewModel.cs和失败的位置:

public class MainWindowViewModel : ViewModelBase
{
    private readonly IAutomatorService _automatorService;
    private readonly ITabService _tabService;

    public MainWindowViewModel(IAutomatorService automatorService, ITabService tabService)
    {
        Argument.IsNotNull(() => automatorService);
        Argument.IsNotNull(() => tabService);

        _automatorService = automatorService;
        _tabService = tabService;

        RunAutomator = new Command<AutomatorModel>(OnRunAutomator, OnRunAutomatorCanExecute);
    }

    public override string Title => "AutoProgram";

    public ObservableCollection<AutomatorModel> Automators
    {
        get { return GetValue<ObservableCollection<AutomatorModel>>(AutomatorsProperty); }
        set { SetValue(AutomatorsProperty, value); }
    }

    public static readonly PropertyData AutomatorsProperty = RegisterProperty("Automators", typeof(ObservableCollection<AutomatorModel>), () => new ObservableCollection<AutomatorModel>());

    public Command<AutomatorModel> RunAutomator { get; private set; }

    public async void OnRunAutomator(AutomatorModel automatorModel)
    {
        Debug.WriteLine($"NAME: {automatorModel.Automator.Name}");
        _tabService.AddAndActivate<AutomatorViewModel>(new AutomatorViewModel(automatorModel), true);   // Throws a null exception in TabItem.cs
        //_tabService.AddAndActivate<AutomatorViewModel>(new AutomatorViewModel(), true);   // But this works (sort of, see bottom error).
    }

}

TabServiceExtensions.cs

public static class TabServiceExtensions
{
    public static TabItem Add<TViewModel>(this ITabService tabService, object dataContext = null, bool canClose = false)
        where TViewModel : IViewModel
    {
        Argument.IsNotNull(() => tabService);

        var tabItem = CreateTabItem<TViewModel>(tabService, dataContext);
        tabItem.CanClose = canClose;

        tabService.Add(tabItem);

        return tabItem;
    }

    public static TabItem AddAndActivate<TViewModel>(this ITabService tabService, object dataContext = null, bool canClose = false)
        where TViewModel : IViewModel
    {
        Argument.IsNotNull(() => tabService);

        var tabItem = Add<TViewModel>(tabService, dataContext, canClose);
        tabService.Activate(tabItem);

        return tabItem;
    }

    public static TabItem CreateTabItem<TViewModel>(this ITabService tabService, object dataContext)
        where TViewModel : IViewModel
    {
        Argument.IsNotNull(() => tabService);

        var dependencyResolver = tabService.GetDependencyResolver();
        var viewModelFactory = dependencyResolver.Resolve<IViewModelFactory>();
        var vm = viewModelFactory.CreateViewModel<TViewModel>(typeof(TViewModel), dataContext);

        return new TabItem(vm);
    }

    public static void AddAndActivate(this ITabService tabService, TabItem tabItem)
    {
        Argument.IsNotNull(() => tabService);
        Argument.IsNotNull(() => tabItem);

        tabService.Add(tabItem);
        tabService.Activate(tabItem);
    }
}

TabItem.cs

public class TabItem
{
    public TabItem(IViewModel viewModel)
    {
        Argument.IsNotNull(() => viewModel);

        ViewModel = viewModel;
        CanClose = true;

        if (!viewModel.IsClosed)
        {
            viewModel.ClosedAsync += OnViewModelClosed;
        }
    }

    public IViewModel ViewModel { get; private set; }

    public bool CanClose { get; set; }

    public object Tag { get; set; }

    public event EventHandler<EventArgs> Closed;

    private async Task OnViewModelClosed(object sender, ViewModelClosedEventArgs e)
    {
        var vm = ViewModel;
        if (vm != null)
        {
            vm.ClosedAsync -= OnViewModelClosed;
        }

        Closed.SafeInvoke(this);
    }
}

我希望TabItems是AutomatorViewModels。后者是这样初始化的:

    public AutomatorViewModel(AutomatorModel automatorModel)
    {
        Title = "Test";
    }

但是上面的代码在TabItem.cs中引发了空Exception。如果我省略构造函数参数，即将其更改为
公共(public)AutomatorViewModel()
确实会以“测试”标题创建标签。尽管在这种情况下，手动关闭这些选项卡时出现以下错误:
System.Windows.Data错误:4:找不到引用'RelativeSource FindAncestor，AncestorType ='System.Windows.Controls.TabControl'，AncestorLevel ='1''的绑定(bind)源。 BindingExpression:Path = TabStripPlacement; DataItem = null;目标元素是'TabItem'(Name ='');目标属性为“NoTarget”(类型“Object”)

App.xaml.cs

    protected override void OnStartup(StartupEventArgs e)
    {
        LogManager.AddDebugListener();

        Log.Info("Starting application");

        StyleHelper.CreateStyleForwardersForDefaultStyles();

        var serviceLocator = ServiceLocator.Default;
        serviceLocator.RegisterType<IAutomatorService, AutomatorService>();
        serviceLocator.RegisterType<ITabService, TabService>();

        // SOME THINGS I'VE TRIED/CURRENTLY TRYING.
        //var dependencyResolver = this.GetDependencyResolver();
        //var viewModelLocator = dependencyResolver.Resolve<IViewModelLocator>();
        //viewModelLocator.Register<AutomatorView, AutomatorViewModel>();
        //viewModelLocator.Register(typeof(AutomatorView), typeof(AutomatorViewModel));
        //viewModelLocator.Register<MainWindow, MainWindowViewModel>();

        Log.Info("Calling base.OnStartup");
        base.OnStartup(e);
    }

卡特尔调试信息:

11:22:39:117 => [DEBUG] [Catel.MVVM.ViewModelBase] [8]创建具有唯一标识符2的'AutomatorViewModel'类型的 View 模型

11:22:39:117 => [DEBUG] [Catel.MVVM.ViewModelCommandManager] [8]为具有唯一标识符“2”的 View 模型“AutoProgram.UI.ViewModels.AutomatorViewModel”创建ViewModelCommandManager

11:22:39:118 => [DEBUG] [Catel.MVVM.ViewModelCommandManager] [8]为具有唯一标识符'2'的 View 模型'AutoProgram.UI.ViewModels.AutomatorViewModel'创建了ViewModelCommandManager

11:22:39:119 => [DEBUG] [Catel.MVVM.ManagedViewModel] [8]添加了 View 模型实例，当前包含类型为'AutoProgram.UI.ViewModels.AutomatorViewModel'的'1'实例

11:22:39:123 => [DEBUG] [Catel.IoC.TypeFactory] ​​[8]使用特定参数创建类型为'AutoProgram.UI.ViewModels.AutomatorViewModel'的实例。在缓存中找不到构造函数，因此请搜索正确的构造函数

11:22:39:124 => [调试] [Catel.IoC.TypeFactory] ​​[8]检查是否可以使用构造函数'public ctor(AutomatorModel automatorModel)'

11:22:39:126 => [DEBUG] [Catel.IoC.TypeFactory] ​​[8]构造函数无效，因为值'AutoProgram.UI.ViewModels.AutomatorViewModel'不能用于参数'AutoProgram.UI.ViewModels.AutomatorViewModel '

11:22:39:126 => [DEBUG] [Catel.IoC.TypeFactory] ​​[8]构造函数有效且可以使用

11:22:39:127 => [DEBUG] [Catel.IoC.TypeFactory] ​​[8]无法使用构造函数，无法使用指定参数构造类型'AutoProgram.UI.ViewModels.AutomatorViewModel'

11:22:39:128 => [DEBUG] [Catel.IoC.TypeFactory] ​​[8]使用特定参数创建类型为'AutoProgram.UI.ViewModels.AutomatorViewModel'的实例。在缓存中找不到构造函数，因此请搜索正确的构造函数

11:22:39:128 => [调试] [Catel.IoC.TypeFactory] ​​[8]检查是否可以使用构造函数'public ctor(AutomatorModel automatorModel)'

11:22:39:129 => [DEBUG] [Catel.IoC.TypeFactory] ​​[8]构造函数无效，因为无法从依赖关系解析器解析参数'automatorModel'

11:22:39:129 => [DEBUG] [Catel.IoC.TypeFactory] ​​[8]构造函数有效且可以使用

11:22:39:130 => [DEBUG] [Catel.IoC.TypeFactory] ​​[8]无法使用构造函数，无法使用指定参数构造类型'AutoProgram.UI.ViewModels.AutomatorViewModel'

11:22:39:130 => [DEBUG] [Catel.MVVM.ViewModelFactory] ​​[8]无法使用注入(inject)数据上下文'AutomatorViewModel'来构建 View 模型'AutoProgram.UI.ViewModels.AutomatorViewModel'
AutoProgram.UI.vshost.exe错误:0:11:22:39:131 => [错误] [Catel.Argument] [8]参数'viewModel'不能为null
引发异常:Catel.Core.dll中的“System.ArgumentNullException”

编辑＃1:

添加了调试信息(未注释的LogManager.AddDebugListener();)

添加了App.xaml.cs

编辑2:

通过将 View 模型的初始化更改为无构造函数的初始化并显式设置模型属性，找到了一种解决方法，如下所示:

_tabService.AddAndActivate(new AutomatorViewModel {AutomatorModel = automatorModel}，false);

最佳答案

您应该将DataContext对象而不是ViewModel传入AddAndActivate。因此，这应该工作(并将为您构建并注入(inject)vm):

_tabService.AddAndActivate<AutomatorViewModel>(automatorModel, true);

关于c# - [Catel]如何将带有构造函数参数的ViewModel传递给TabServiceExtensions方法？，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/42014978/