Null Reference Exception requests data in EF6 after upgrade from EF4
I am having trouble getting data from my infrastructure context. I am updating my app from entities 4 to 6 and it was not a party.
Right now, if I try to query any records from my database, I get a null reference exception.
DBSet<EntityObject> test1 = context.EntityObjects;
List<EntityObject> test2 = test1.ToList();
The first line works without error. The second line throws a System.NullReferenceException with the following stack trace:
at System.Data.Entity.Core.Metadata.Edm.OSpaceTypeFactory.TypesMatchByConvention(Type type, EdmType cspaceType)
at System.Data.Entity.Core.Metadata.Edm.OSpaceTypeFactory.TryCreateStructuralType(Type type, StructuralType cspaceType, EdmType& newOSpaceType)
at System.Data.Entity.Core.Metadata.Edm.OSpaceTypeFactory.TryCreateType(Type type, EdmType cspaceType)
at System.Data.Entity.Core.Metadata.Edm.ObjectItemConventionAssemblyLoader.LoadTypesFromAssembly()
at System.Data.Entity.Core.Metadata.Edm.ObjectItemAssemblyLoader.Load()
at System.Data.Entity.Core.Metadata.Edm.AssemblyCache.LoadAssembly(Assembly assembly, Boolean loadReferencedAssemblies, ObjectItemLoadingSessionData loadingData)
at System.Data.Entity.Core.Metadata.Edm.AssemblyCache.LoadAssembly(Assembly assembly, Boolean loadReferencedAssemblies, KnownAssembliesSet knownAssemblies, EdmItemCollection edmItemCollection, Action`1 logLoadMessage, Object& loaderCookie, Dictionary`2& typesInLoading, List`1& errors)
at System.Data.Entity.Core.Metadata.Edm.ObjectItemCollection.LoadAssemblyFromCache(Assembly assembly, Boolean loadReferencedAssemblies, EdmItemCollection edmItemCollection, Action`1 logLoadMessage)
at System.Data.Entity.Core.Metadata.Edm.ObjectItemCollection.ExplicitLoadFromAssembly(Assembly assembly, EdmItemCollection edmItemCollection, Action`1 logLoadMessage)
at System.Data.Entity.Core.Metadata.Edm.MetadataWorkspace.ExplicitLoadFromAssembly(Assembly assembly, ObjectItemCollection collection, Action`1 logLoadMessage)
at System.Data.Entity.Core.Metadata.Edm.MetadataWorkspace.LoadFromAssembly(Assembly assembly, Action`1 logLoadMessage)
at System.Data.Entity.Core.Metadata.Edm.MetadataWorkspace.LoadFromAssembly(Assembly assembly)
at System.Data.Entity.Internal.InternalContext.TryUpdateEntitySetMappingsForType(Type entityType)
at System.Data.Entity.Internal.InternalContext.UpdateEntitySetMappingsForType(Type entityType)
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.GetEnumerator()
at System.Data.Entity.Infrastructure.DbQuery`1.System.Collections.Generic.IEnumerable<TResult>.GetEnumerator()
at System.Collections.Generic.List`1..ctor(IEnumerable`1 collection)
at System.Linq.Enumerable.ToList[TSource](IEnumerable`1 source)
at ConnectServer.ConnectModule.handleReceive(Message message, ClientConnection client) in c:\Users\Eric Bowman\Documents\Visual Studio 2012\Projects\NXConnect_ME578_Interoperability\CADInteroperabilityCATIA\ConnectServer\ConnectModule.cs:line 137
Now I guess the problem is with my connection string that prevents the context from connecting to the database, so here is my config file:
<?xml version="1.0" encoding="utf-8"?>
<configuration>
<configSections>
<section name="entityFramework" type="System.Data.Entity.Internal.ConfigFile.EntityFrameworkSection, EntityFramework, Version=6.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089" requirePermission="false" />
<!-- For more information on Entity Framework configuration, visit http://go.microsoft.com/fwlink/?LinkID=237468 -->
</configSections>
<connectionStrings>
<add name="FancyEntities" connectionString="metadata=res://*/ConnectData.csdl|res://*/ConnectData.ssdl|res://*/ConnectData.msl;provider=System.Data.SqlClient;provider connection string="data source=localhost,1433;initial catalog=Fancy_Dev;Persist Security Info=True;User ID=******;Password=************;MultipleActiveResultSets=True""
providerName="System.Data.EntityClient"/>
</connectionStrings>
<entityFramework>
<defaultConnectionFactory type="System.Data.Entity.Infrastructure.SqlConnectionFactory, EntityFramework" />
<providers>
<provider invariantName="System.Data.SqlClient" type="System.Data.Entity.SqlServer.SqlProviderServices, EntityFramework.SqlServer" />
</providers>
</entityFramework>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5" />
</startup>
Did I miss something? Could it be something else?
UPDATE
The connection string was bad, but even after fixing it, I get exactly the same error. I can open a database connection, but when I try to look at any of the collections in context, it throws a null reference exception.
This is very frustrating
Another update
I didn’t help very well, so I am posting some of the information I found.
I found the Entity Framework source and this is the method that fails:
internal static bool TypesMatchByConvention(Type type, EdmType cspaceType)
{
return type.Name == cspaceType.Name;
}
And here's the previous block of code that calls the method:
if (cspaceType.BaseType != null)
{
if (TypesMatchByConvention(type.BaseType, cspaceType.BaseType))
{
TrackClosure(type.BaseType);
referenceResolutionListForCurrentType.Add(
() => ospaceType.BaseType = ResolveBaseType((StructuralType)cspaceType.BaseType, type));
}
else
{
var message = Strings.Validator_OSpace_Convention_BaseTypeIncompatible(
type.BaseType.FullName, type.FullName, cspaceType.BaseType.FullName);
LogLoadMessage(message, cspaceType);
return false;
}
}
Note that it checks for cspaceType.BaseType for null, but not type.BaseType.
I created a new project with the same entity model and it works great, so it has to do with my specific settings or project or whatever.
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I had a bad link line when I posted it, so watch out for this, but it wasn't really the problem
the problem was a name conflict. One of my classes in Entity Framework had the same name as a class in one of my other links.
So, as a general practice, I recommend giving each of your Entity Framework classes a prefix so that it is absolutely sure that it will never be the same as any class you might use in any library.
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I cannot find the EntityObjects property in the EF6 documentation. Are you sure you have completely removed all references to EF4 from your project?
Perhaps you can also replace the code like this:
EntityObject e = context.EntityObjects.FirstOrDefault();
And see what is the meaning e
? Finally, if you are trying to select all objects from a table in your database and put them in List
, isn't that an option?
var myObjects = (from s in context.tableName select s).ToList();
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I had a somewhat similar problem where every time I called ToListAsync () on the DbSet EF a NullReferenceException was thrown. For the sake of anyone getting here from Google (I didn't find any help on the web), in my case it was a confusion from calling asynchronous code synchronously (attribute constraint from third party framework).
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