Hi,
I wonder if someone can help me.
I'm using VS2010, .Net 4, EF4 and I'm trying to generate an objectcontext which is configured entirely in code (code-only as opposed to model-first or db-first).
In short, I do:
- Create a ContextBuilder
- Configure ContextBuilder for each entity (specifying PK, FKs, Nullable, etc.)
- I ask the ContextBuilder to create a context for me using the provided connection string.
The last step above fails with the following exception:
Unable to infer a key for entity type 'MyNamespace.MyEntityName'.
I take this to mean it can't infer a Primary Key/Identity column for my entity.
My code is below. The ContextExtension
referenced is a wrapper class which simply inherits from ObjectContext
.
''Process starts with a call to this function
Private Shared Function GenerateContext() As ObjectContext
Dim ConnectionStringDetails = System.Configuration.ConfigurationManager.ConnectionStrings("MyConnectionString")
Dim Builder = New ContextBuilder(Of ContextExtension)()
ConfigureDatabase(Builder)
'' Below line throws an exception:
'' Unable to infer a key for entity type 'MyNamespace.Sector'
Dim NewContext = Builder.Create(New SqlConnection(ConnectionStringDetails.ConnectionString))
Return DirectCast(NewContext, ObjectContext)
End Function
Private Shared Sub ConfigureDatabase(ByRef Builder As ContextBuilder(Of ContextExtension))
''Apply configurations for each of my 3 entities (see code blocks below for efinitions)
ConfigureEntity(Builder, New SectorConfig)
ConfigureEntity(Builder, New SolarSystemConfig)
ConfigureEntity(Builder, New UniverseConfig)
End Sub
Private Shared Sub ConfigureEntity(Of T)(ByRef Builder As ContextBuilder(Of ContextExtension), ByVal config As EntityConfiguration(Of T))
''simple pluralization of the entity set
ConfigureEntity(Builder, config, GetType(T).Name & "s")
End Sub
Private Shared Sub ConfigureEntity(Of T)(ByRef Builder As ContextBuilder(Of ContextExtension), ByVal config As EntityConfiguration(Of T), ByVal setName As String)
''add the configuration
Builder.Configurations.Add(config)
''register the set metadata
Builder.RegisterSet(Of T)(setName)
End Sub
My entities are defined as below:
Public Class Sector
Implements IEntity
Public Overridable Property id As Long Implements IEntity.id
Public Overridable Property Universe As Universe
Public Overridable Property SolarSystems As ICollection(Of SolarSystem)
End Class
And my entity configurations are like this:
Public Class SectorConfig
Inherits EntityConfiguration(Of Sector)
Public Sub New()
[Property](Function(x) x.id).IsIdentity()
Relationship(Function(x) x.Universe).FromProperty(Function(y) y.Sectors).IsRequired()
End Sub
End Class
If I exclude sector from the config, the same happens to the next entity an so on - so either all entities/configs are wrong or it's not an entity/config problem
If I examine Builder
just before the Create()
call, I can see 3 configurations which match my entities and the id
fields specified have the following: (My comments in []s)
Builder.Configurations.Items(0)[Sector].Items(0)[id].Value.StoreGeneratedPattern = Identity {1}
Which seems to imply that the configuration is being applied correctly.
Can someone please explain why I'm getting the exception and how to go about resolving the problem?
Many thanks