Question

我刚刚将项目切换到尝试使用.NET 4.0运行的Entity Framework 5.0 RC。除了更新命名空间引用之外，我们还没有进行任何代码更改。我们第一次尝试访问实体框架对象时，我得到以下内容：

   at System.Data.Entity.ModelConfiguration.Conventions.ForeignKeyNavigationPropertyAttributeConvention.System.Data.Entity.ModelConfiguration.Conventions.IEdmConvention<System.Data.Entity.Edm.EdmNavigationProperty>.Apply(EdmNavigationProperty navigationProperty, EdmModel model)
   at System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.EdmConventionDispatcher.Dispatch[TEdmDataModelItem](TEdmDataModelItem item)
   at System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.EdmConventionDispatcher.VisitEdmNavigationProperty(EdmNavigationProperty item)
   at System.Data.Entity.Edm.Internal.DataModelItemVisitor.VisitCollection[T](IEnumerable`1 collection, Action`1 visitMethod)
   at System.Data.Entity.Edm.Internal.EdmModelVisitor.VisitDeclaredNavigationProperties(EdmEntityType entityType, IEnumerable`1 navigationProperties)
   at System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.EdmConventionDispatcher.VisitEdmEntityType(EdmEntityType item)
   at System.Data.Entity.Edm.Internal.DataModelItemVisitor.VisitCollection[T](IEnumerable`1 collection, Action`1 visitMethod)
   at System.Data.Entity.Edm.Internal.EdmModelVisitor.VisitEntityTypes(EdmNamespace edmNamespace, IEnumerable`1 entityTypes)
   at System.Data.Entity.Edm.Internal.EdmModelVisitor.VisitEdmNamespace(EdmNamespace item)
   at System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.EdmConventionDispatcher.VisitEdmNamespace(EdmNamespace item)
   at System.Data.Entity.Edm.Internal.DataModelItemVisitor.VisitCollection[T](IEnumerable`1 collection, Action`1 visitMethod)
   at System.Data.Entity.Edm.Internal.EdmModelVisitor.VisitNamespaces(EdmModel model, IEnumerable`1 namespaces)
   at System.Data.Entity.Edm.Internal.EdmModelVisitor.VisitEdmModel(EdmModel item)
   at System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.EdmConventionDispatcher.VisitEdmModel(EdmModel item)
   at System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.EdmConventionDispatcher.Dispatch()
   at System.Data.Entity.ModelConfiguration.Configuration.ConventionsConfiguration.ApplyModel(EdmModel model)
   at System.Data.Entity.DbModelBuilder.Build(DbProviderManifest providerManifest, DbProviderInfo providerInfo)
   at System.Data.Entity.DbModelBuilder.Build(DbConnection providerConnection)
   at System.Data.Entity.Internal.LazyInternalContext.CreateModel(LazyInternalContext internalContext)
   at System.Data.Entity.Internal.RetryLazy`2.GetValue(TInput input)
   at System.Data.Entity.Internal.LazyInternalContext.InitializeContext()
   at System.Data.Entity.Internal.InternalContext.Initialize()
   at System.Data.Entity.Internal.InternalContext.GetEntitySetAndBaseTypeForType(Type entityType)
   at System.Data.Entity.Internal.Linq.InternalSet`1.Initialize()
   at System.Data.Entity.Internal.Linq.InternalSet`1.get_InternalContext()
   at System.Data.Entity.Infrastructure.DbQuery`1.System.Linq.IQueryable.get_Provider()
   at System.Linq.Queryable.FirstOrDefault[TSource](IQueryable`1 source, Expression`1 predicate)
   at BackEnd.Facade.Implementations.UserService.GetUserByUserName(String userName) in c:\Development\FundApps\Rapptr\src\FundApps.Rapptr.ServiceLayer\Facade\Implementations\UserService.cs:line 61
   at FundApps.Rapptr.Common.Web.Security.WebUserContextModule.OnPostAuthenticateRequest(HttpContextBase context) in c:\Development\FundApps\Rapptr\src\FundApps.Rapptr.Common.Web\Security\WebUserContextModule.cs:line 54
   at FundApps.Common.Mvc.BaseHttpModule.<Init>b__1(Object sender, EventArgs e) in c:\Development\FundApps\Rapptr\src\FundApps.Common.Mvc\BaseHttpModule.cs:line 14
   at System.Web.HttpApplication.SyncEventExecutionStep.System.Web.HttpApplication.IExecutionStep.Execute()
   at System.Web.HttpApplication.ExecuteStep(IExecutionStep step, Boolean& completedSynchronously)

有没有人对可能导致这种情况的原因以及如何缩小范围提出任何建议？

Answer 1

更新：此错误已在EF5 RTM中修复。

这是EF5中的一个错误。当您具有1：1关系并且还使用ForeignKey属性来明确指定FK时，会发生这种情况。例如：

public class OneToOneResult
{
    public int OneToOneResultId { get; set; }

    [ForeignKey("OneToOneResultId")]
    public virtual OneToOneResultDetail Detail { get; set; }
}

public class OneToOneResultDetail
{
   [Key]
   public int OneToOneResultId { get; set; }
   public DateTime DataDate { get; set; }
}

在OnModelCreating：

modelBuilder.Entity<OneToOneResult>()
   .HasRequired(r => r.Detail)
   .WithRequiredPrincipal();

解决方法是删除ForeignKey属性。在这种情况下不需要它，因为1：1关系必须是PK到PK，因为在这种情况下，这就是EF支持的所有内容。

实体框架4.3.1到5.0 RC - 模型创建期间的NullReferenceException

1 个答案: