实体框架:无法加载上下文

Question

我正在设置实体框架，但遇到了一些麻烦。我正在使用MVC，EF 6.0，.net Framework 4.5.1

在我的 Web 配置中，我在实体框架节点中拥有以下内容：

<contexts>
      <context type="MyApp.Data.UserContext">
        <databaseInitializer type="MyApp.Data.UserContextInit" />
      </context>
    </contexts>

但是，当我尝试运行我的应用程序时，出现以下错误：

Could not load type 'MyApp.Data.UserContext' from assembly 'EntityFramework'.

这是来自 Web 配置的完整实体框架节点：

<entityFramework>
    <contexts>
      <context type="MyApp.Data.UserContext">
        <databaseInitializer type="MyApp.Data.UserContextInit" />
      </context>
    </contexts>
    <defaultConnectionFactory type="System.Data.Entity.Infrastructure.LocalDbConnectionFactory, EntityFramework">
      <parameters>
        <parameter value="mssqllocaldb" />
      </parameters>
    </defaultConnectionFactory>
    <providers>
      <provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
    </providers>
  </entityFramework>

这是整个堆栈跟踪：

[TypeLoadException: Could not load type 'MyApp.Data.UserContext' from assembly 'EntityFramework'.]
   System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMarkHandle stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName, ObjectHandleOnStack type) +0
   System.RuntimeTypeHandle.GetTypeByName(String name, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark, IntPtr pPrivHostBinder, Boolean loadTypeFromPartialName) +70
   System.RuntimeType.GetType(String typeName, Boolean throwOnError, Boolean ignoreCase, Boolean reflectionOnly, StackCrawlMark& stackMark) +40
   System.Type.GetType(String typeName, Boolean throwOnError) +34
   System.Data.Entity.Internal.InitializerConfig.TryGetInitializer(Type requiredContextType, String contextTypeName, String initializerTypeName, Boolean isDisabled, Func`1 initializerArgs, Func`3 exceptionMessage) +39
[InvalidOperationException: Failed to set database initializer of type 'MyApp.Data.UserContextInit' for DbContext type 'MyApp.Data.UserContext, EntityFramework' specified in the application configuration. See inner exception for details.]
   System.Data.Entity.Internal.InitializerConfig.TryGetInitializer(Type requiredContextType, String contextTypeName, String initializerTypeName, Boolean isDisabled, Func`1 initializerArgs, Func`3 exceptionMessage) +232
   System.Data.Entity.Internal.<>c__DisplayClass6.<TryGetInitializerFromEntityFrameworkSection>b__1(ContextElement e) +199
   System.Linq.WhereSelectEnumerableIterator`2.MoveNext() +164
   System.Linq.Enumerable.FirstOrDefault(IEnumerable`1 source, Func`2 predicate) +94
   System.Data.Entity.Internal.InitializerConfig.TryGetInitializerFromEntityFrameworkSection(Type contextType) +250
   System.Data.Entity.Internal.InitializerConfig.TryGetInitializer(Type contextType) +18
   System.Data.Entity.Infrastructure.DependencyResolution.AppConfigDependencyResolver.GetServiceFactory(Type type, String name) +439
   System.Data.Entity.Infrastructure.DependencyResolution.<>c__DisplayClass1.<GetService>b__0(Tuple`2 t) +42
   System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd(TKey key, Func`2 valueFactory) +72
   System.Data.Entity.Infrastructure.DependencyResolution.AppConfigDependencyResolver.GetService(Type type, Object key) +140
   System.Data.Entity.Infrastructure.DependencyResolution.<>c__DisplayClass3.<GetService>b__0(IDbDependencyResolver r) +19
   System.Linq.WhereSelectArrayIterator`2.MoveNext() +58
   System.Linq.Enumerable.FirstOrDefault(IEnumerable`1 source, Func`2 predicate) +94
   System.Data.Entity.Infrastructure.DependencyResolution.ResolverChain.GetService(Type type, Object key) +160
   System.Data.Entity.Infrastructure.DependencyResolution.CompositeResolver`2.GetService(Type type, Object key) +39
   System.Data.Entity.Infrastructure.DependencyResolution.DbDependencyResolverExtensions.GetService(IDbDependencyResolver resolver, Type type) +56
   System.Data.Entity.Internal.InternalContext.PerformDatabaseInitialization() +125
   System.Data.Entity.Internal.LazyInternalContext.<InitializeDatabase>b__4(InternalContext c) +7
   System.Data.Entity.Internal.RetryAction`1.PerformAction(TInput input) +110
   System.Data.Entity.Internal.LazyInternalContext.InitializeDatabaseAction(Action`1 action) +198
   System.Data.Entity.Internal.LazyInternalContext.InitializeDatabase() +73
   System.Data.Entity.Internal.InternalContext.Initialize() +30
   System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType) +16
   System.Data.Entity.Internal.Linq.InternalSet`1.Initialize() +53
   System.Data.Entity.Internal.Linq.InternalSet`1.GetEnumerator() +15
   System.Data.Entity.Infrastructure.DbQuery`1.System.Collections.Generic.IEnumerable<TResult>.GetEnumerator() +53
   System.Collections.Generic.List`1..ctor(IEnumerable`1 collection) +375
   System.Linq.Enumerable.ToList(IEnumerable`1 source) +58
   MyApp.WebMS.Controllers.HomeController.Index() in C:UsersBen DonnellyDocumentsVisual Studio 2017ProjectsTechTestMyAppMyApp.WebMSControllersHomeController.cs:18
   lambda_method(Closure , ControllerBase , Object[] ) +61
   System.Web.Mvc.ActionMethodDispatcher.Execute(ControllerBase controller, Object[] parameters) +14
   System.Web.Mvc.ReflectedActionDescriptor.Execute(ControllerContext controllerContext, IDictionary`2 parameters) +157
   System.Web.Mvc.ControllerActionInvoker.InvokeActionMethod(ControllerContext controllerContext, ActionDescriptor actionDescriptor, IDictionary`2 parameters) +27
   System.Web.Mvc.Async.AsyncControllerActionInvoker.<BeginInvokeSynchronousActionMethod>b__39(IAsyncResult asyncResult, ActionInvocation innerInvokeState) +22
   System.Web.Mvc.Async.WrappedAsyncResult`2.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethod(IAsyncResult asyncResult) +32
   System.Web.Mvc.Async.AsyncInvocationWithFilters.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3d() +50
   System.Web.Mvc.Async.<>c__DisplayClass46.<InvokeActionMethodFilterAsynchronouslyRecursive>b__3f() +228
   System.Web.Mvc.Async.<>c__DisplayClass33.<BeginInvokeActionMethodWithFilters>b__32(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeActionMethodWithFilters(IAsyncResult asyncResult) +34
   System.Web.Mvc.Async.<>c__DisplayClass2b.<BeginInvokeAction>b__1c() +26
   System.Web.Mvc.Async.<>c__DisplayClass21.<BeginInvokeAction>b__1e(IAsyncResult asyncResult) +100
   System.Web.Mvc.Async.WrappedAsyncResult`1.CallEndDelegate(IAsyncResult asyncResult) +10
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Async.AsyncControllerActionInvoker.EndInvokeAction(IAsyncResult asyncResult) +27
   System.Web.Mvc.Controller.<BeginExecuteCore>b__1d(IAsyncResult asyncResult, ExecuteCoreState innerState) +13
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Controller.EndExecuteCore(IAsyncResult asyncResult) +36
   System.Web.Mvc.Controller.<BeginExecute>b__15(IAsyncResult asyncResult, Controller controller) +12
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +22
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.Controller.EndExecute(IAsyncResult asyncResult) +26
   System.Web.Mvc.Controller.System.Web.Mvc.Async.IAsyncController.EndExecute(IAsyncResult asyncResult) +10
   System.Web.Mvc.MvcHandler.<BeginProcessRequest>b__5(IAsyncResult asyncResult, ProcessRequestState innerState) +21
   System.Web.Mvc.Async.WrappedAsyncVoid`1.CallEndDelegate(IAsyncResult asyncResult) +29
   System.Web.Mvc.Async.WrappedAsyncResultBase`1.End() +49
   System.Web.Mvc.MvcHandler.EndProcessRequest(IAsyncResult asyncResult) +28
   System.Web.Mvc.MvcHandler.System.Web.IHttpAsyncHandler.EndProcessRequest(IAsyncResult result) +9
   System.Web.CallHandlerExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute() +9748665
   System.Web.HttpApplication.ExecuteStepImpl(IExecutionStep step) +48
   System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously) +159

我一直在按照 Microsoft 文档进行设置，我注意到的一件事是他们在指定上下文的完整路径后将程序集放在我第一次显示的上下文节点中。这是文档链接;https://learn.microsoft.com/en-us/aspnet/mvc/overview/getting-started/getting-started-with-ef-using-mvc/creating-an-entity-framework-data-model-for-an-asp-net-mvc-application#main

Answer 1

该错误几乎说明了问题所在，代码正在查找您在错误程序集中指定的类型。若要解决此问题，您需要使用可以找到它的程序集限定您的类型。例如：

<databaseInitializer type="MyApp.Data.UserContextInit, MyAssemblyName" />