如何recomposit空DirectoryCatalog为MEF在WPF

Question

我与这些步骤中的应用：

1. 启动应用程序和ConfigureAggregateCatalog
2. 登录用户到App
3. 下载DLL MEF模块，以所谓的“模块”目录
4. 刷新目录目录 - 有问题

我有空的目录'模块'后下载DLL我试图加载模块，但没有成功。有上线的错误，我叫DirectoryCatalog.Refresh（）

System.ComponentModel.Composition.ChangeRejectedException was unhandled by user code Message=The composition remains unchanged. The changes were rejected because of the following error(s): The composition produced multiple composition errors, with 14 root causes. The root causes are provided below. Review the CompositionException.Errors property for more detailed information.

1) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleInitializer..ctor (Parameter="downloadedPartCatalogs", ContractName="Microsoft.Practices.Prism.MefExtensions.Modularity.DownloadedPartCatalogCollection")' on part 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleInitializer'.

2) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager.mefFileModuleTypeLoader (ContractName="Microsoft.Practices.Prism.MefExtensions.Modularity.MefFileModuleTypeLoader")' on part 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager'.

3) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager..ctor (Parameter="moduleInitializer", ContractName="Microsoft.Practices.Prism.Modularity.IModuleInitializer")' on part 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager'.

4) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager.mefFileModuleTypeLoader (ContractName="Microsoft.Practices.Prism.MefExtensions.Modularity.MefFileModuleTypeLoader")' on part 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager'.

5) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager..ctor (Parameter="moduleInitializer", ContractName="Microsoft.Practices.Prism.Modularity.IModuleInitializer")' on part 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager'.

6) Change in exports prevented by non-recomposable import 'GXBilling.ViewsModels.ShellViewModel.ModuleManager (ContractName="Microsoft.Practices.Prism.Modularity.IModuleManager")' on part 'GXBilling.ViewsModels.ShellViewModel'.

7) More than one export was found that matches the constraint '((exportDefinition.ContractName == "Microsoft.Practices.Prism.Regions.RegionAdapterMappings") AndAlso (exportDefinition.Metadata.ContainsKey("ExportTypeIdentity") AndAlso "Microsoft.Practices.Prism.Regions.RegionAdapterMappings".Equals(exportDefinition.Metadata.get_Item("ExportTypeIdentity"))))'.

Resulting in: Cannot set import 'Microsoft.Practices.Prism.MefExtensions.Regions.Behaviors.MefDelayedRegionCreationBehavior..ctor (Parameter="regionAdapterMappings", ContractName="Microsoft.Practices.Prism.Regions.RegionAdapterMappings")' on part 'Microsoft.Practices.Prism.MefExtensions.Regions.Behaviors.MefDelayedRegionCreationBehavior'. Element: Microsoft.Practices.Prism.MefExtensions.Regions.Behaviors.MefDelayedRegionCreationBehavior..ctor (Parameter="regionAdapterMappings", ContractName="Microsoft.Practices.Prism.Regions.RegionAdapterMappings") --> Microsoft.Practices.Prism.MefExtensions.Regions.Behaviors.MefDelayedRegionCreationBehavior --> AssemblyCatalog (Assembly="Microsoft.Practices.Prism.MefExtensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35")

8) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Regions.MefSelectorRegionAdapter..ctor (Parameter="regionBehaviorFactory", ContractName="Microsoft.Practices.Prism.Regions.IRegionBehaviorFactory")' on part 'Microsoft.Practices.Prism.MefExtensions.Regions.MefSelectorRegionAdapter'.

9) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Regions.MefItemsControlRegionAdapter..ctor (Parameter="regionBehaviorFactory", ContractName="Microsoft.Practices.Prism.Regions.IRegionBehaviorFactory")' on part 'Microsoft.Practices.Prism.MefExtensions.Regions.MefItemsControlRegionAdapter'.

10) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Regions.MefContentControlRegionAdapter..ctor (Parameter="regionBehaviorFactory", ContractName="Microsoft.Practices.Prism.Regions.IRegionBehaviorFactory")' on part 'Microsoft.Practices.Prism.MefExtensions.Regions.MefContentControlRegionAdapter'.

11) More than one export was found that matches the constraint '((exportDefinition.ContractName == "Microsoft.Practices.Prism.Regions.IRegionViewRegistry") AndAlso (exportDefinition.Metadata.ContainsKey("ExportTypeIdentity") AndAlso "Microsoft.Practices.Prism.Regions.IRegionViewRegistry".Equals(exportDefinition.Metadata.get_Item("ExportTypeIdentity"))))'.

Resulting in: Cannot set import 'Microsoft.Practices.Prism.MefExtensions.Regions.Behaviors.MefAutoPopulateRegionBehavior..ctor (Parameter="regionViewRegistry", ContractName="Microsoft.Practices.Prism.Regions.IRegionViewRegistry")' on part 'Microsoft.Practices.Prism.MefExtensions.Regions.Behaviors.MefAutoPopulateRegionBehavior'. Element: Microsoft.Practices.Prism.MefExtensions.Regions.Behaviors.MefAutoPopulateRegionBehavior..ctor (Parameter="regionViewRegistry", ContractName="Microsoft.Practices.Prism.Regions.IRegionViewRegistry") --> Microsoft.Practices.Prism.MefExtensions.Regions.Behaviors.MefAutoPopulateRegionBehavior --> AssemblyCatalog (Assembly="Microsoft.Practices.Prism.MefExtensions, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35")

12) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleInitializer..ctor (Parameter="downloadedPartCatalogs", ContractName="Microsoft.Practices.Prism.MefExtensions.Modularity.DownloadedPartCatalogCollection")' on part 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleInitializer'.

13) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager.mefFileModuleTypeLoader (ContractName="Microsoft.Practices.Prism.MefExtensions.Modularity.MefFileModuleTypeLoader")' on part 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager'.

14) Change in exports prevented by non-recomposable import 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager..ctor (Parameter="moduleInitializer", ContractName="Microsoft.Practices.Prism.Modularity.IModuleInitializer")' on part 'Microsoft.Practices.Prism.MefExtensions.Modularity.MefModuleManager'.

Source=System.ComponentModel.Composition StackTrace: at System.ComponentModel.Composition.CompositionResult.ThrowOnErrors(AtomicComposition atomicComposition) at System.ComponentModel.Composition.Hosting.ExportProvider.OnExportsChanging(ExportsChangeEventArgs e) at System.ComponentModel.Composition.Hosting.CatalogExportProvider.OnCatalogChanging(Object sender, ComposablePartCatalogChangeEventArgs e) at System.ComponentModel.Composition.Hosting.ComposablePartCatalogCollection.OnChanging(Object sender, ComposablePartCatalogChangeEventArgs e) at System.ComponentModel.Composition.Hosting.AggregateCatalog.OnChanging(ComposablePartCatalogChangeEventArgs e) at System.ComponentModel.Composition.Hosting.ComposablePartCatalogCollection.OnContainedCatalogChanging(Object sender, ComposablePartCatalogChangeEventArgs e) at System.ComponentModel.Composition.Hosting.DirectoryCatalog.OnChanging(ComposablePartCatalogChangeEventArgs e) at System.ComponentModel.Composition.Hosting.DirectoryCatalog.Refresh() at GXBilling.Bootstrapper.RefreshCatalog() in E:\Projects!New!\GXBilling\GXBilling\Bootstrapper.cs:line 36 at GXBilling.ViewsModels.WinLogOnViewModel.FWCore_OnDownloadedModulesCompleted(Object sender, EventArgs e) in E:\Projects!New!\GXBilling\GXBilling\ViewsModels\WinLogOnViewModel.cs:line 168 at BillingCore.FWCore.FWCore_ModuleDownloadedCompleted(Object sender, ModuleDownloadedEventArgs e) in E:\Projects!New!\GXBilling\BillingCore\FWCore.cs:line 169 at BillingCore.FWCore.client_DownloadFileCompleted(Object sender, DownloadFileCompletedEventArgs e) in E:\Projects!New!\GXBilling\BillingCore\FWCore.cs:line 207 at BillingCore.BillingServiceRef.FileTransferServiceClient.OnDownloadFileCompleted(Object state) in E:\Projects!New!\GXBilling\BillingCore\Service References\BillingServiceRef\Reference.cs:line 739 at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.DispatcherOperation.InvokeImpl() at System.Windows.Threading.DispatcherOperation.InvokeInSecurityContext(Object state) at System.Threading.ExecutionContext.runTryCode(Object userData) at System.Runtime.CompilerServices.RuntimeHelpers.ExecuteCodeWithGuaranteedCleanup(TryCode code, CleanupCode backoutCode, Object userData) at System.Threading.ExecutionContext.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx) at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state) at System.Windows.Threading.DispatcherOperation.Invoke() at System.Windows.Threading.Dispatcher.ProcessQueue() at System.Windows.Threading.Dispatcher.WndProcHook(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndWrapper.WndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam, Boolean& handled) at MS.Win32.HwndSubclass.DispatcherCallbackOperation(Object o) at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs) at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler) at System.Windows.Threading.Dispatcher.InvokeImpl(DispatcherPriority priority, TimeSpan timeout, Delegate method, Object args, Int32 numArgs) at MS.Win32.HwndSubclass.SubclassWndProc(IntPtr hwnd, Int32 msg, IntPtr wParam, IntPtr lParam) at MS.Win32.UnsafeNativeMethods.DispatchMessage(MSG& msg) at System.Windows.Threading.Dispatcher.PushFrameImpl(DispatcherFrame frame) at System.Windows.Threading.Dispatcher.PushFrame(DispatcherFrame frame) at System.Windows.Window.ShowHelper(Object booleanBox) at System.Windows.Window.Show() at System.Windows.Window.ShowDialog() InnerException:

还有就是通过属性导入标记的部分代码：

[Import] 
public ShellViewModel ViewModel 

[Import(AllowRecomposition = false)] 
public IModuleManager ModuleManager { get; set; } 

[Import(typeof(IShell), AllowRecomposition = true)] 
public IShell MainShell { get; set; } 

[ImportingConstructor] 
public ModuleImporting(IRegionManager regionManager) 

这就是全部。我没有IEnureable或IList或在代码中。那么问题在哪里？

Answer 1

刷新DirectoryCatalog触发recomposition。在MEF部分的进口只能重新构图，如果它被明确标出，例如像这样：

[ImportMany(typeof(IFoo),AllowRecomposition=true)] 
IEnumerable<IFoo> Foos { private get; set; } 

如果导入由重排的影响，但没有打上AllowRecomposition=true，那么你出现错误：“由不可重新导入导致的出口更改”。

另外，通过构造函数导入根本不支持重构。但是，you can work around this。

Answer 2

每当有类似的错误：

"Activation error occurred while trying to get instance of type , key "" "

然后请[Export]属性是否在<User Control page>规定，我们将会在Region注入。

这是一件小事情，但可以浪费你的时间在调试！

谢谢！ Bassi