EF4 POCO (not using T4): Mapping and metadata information could not be found for EntityType

Question

I have a pretty simple console project with an entity model (containing two simple entities), two handmade POCOs and a handmade Context class. The program fires a simple query against the DB and everything including LazyLoading works fine.

The problem: As soon as i add another Entity data model (even if i add an empty one), the calls to CreateObjectSet in Ef2PlaygroundModel_3Container throw the following exception:

Unhandled Exception: System.InvalidOperationException: Mapping and metadata information could not be found for EntityType 'EF2_Playground.Driver'.
  at System.Data.Objects.ObjectContext.GetTypeUsage(Type entityCLRType)
  at System.Data.Objects.ObjectContext.GetEntitySetFromContainer(EntityContainer container, Type entityCLRType, String exceptionParameterName)
  at System.Data.Objects.ObjectContext.GetEntitySetForType(Type entityCLRType, String exceptionParameterName)
  at System.Data.Objects.ObjectContext.CreateObjectSet[TEntity]()
  at EF2_Playground.Ef2PlaygroundModel_3Container.get_Drivers() in C:\...\Ef2PlaygroundModel_3Pocos.cs:line 64
  at EF2_Playground.Program.Main(String[] args) in C:\...\Program.cs:line 15

Does anyone have an idea about what is going wrong here?

---

That is the working project:

Ef2PlaygroundModel_3.edmx:

Code Generation Strategy is set to "None"

<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="2.0" xmlns:edmx="http://schemas.microsoft.com/ado/2008/10/edmx">
  <!-- EF Runtime content -->
  <edmx:Runtime>
    <!-- SSDL content -->
    <edmx:StorageModels>
      <Schema Namespace="Ef2PlaygroundModel_3.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2008" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" xmlns="http://schemas.microsoft.com/ado/2009/02/edm/ssdl">
        <EntityContainer Name="Ef2PlaygroundModel_3StoreContainer">
          <EntitySet Name="Cars" EntityType="Ef2PlaygroundModel_3.Store.Cars" store:Type="Tables" Schema="dbo"/>
          <EntitySet Name="Drivers" EntityType="Ef2PlaygroundModel_3.Store.Drivers" store:Type="Tables" Schema="dbo"/>
          <EntitySet Name="CarDriver" EntityType="Ef2PlaygroundModel_3.Store.CarDriver" store:Type="Tables" Schema="dbo"/>
          <AssociationSet Name="FK_CarDriver_Car" Association="Ef2PlaygroundModel_3.Store.FK_CarDriver_Car">
            <End Role="Car" EntitySet="Cars"/>
            <End Role="CarDriver" EntitySet="CarDriver"/>
          </AssociationSet>
          <AssociationSet Name="FK_CarDriver_Driver" Association="Ef2PlaygroundModel_3.Store.FK_CarDriver_Driver">
            <End Role="Driver" EntitySet="Drivers"/>
            <End Role="CarDriver" EntitySet="CarDriver"/>
          </AssociationSet>
        </EntityContainer>
        <EntityType Name="Cars">
          <Key>
            <PropertyRef Name="Id"/>
          </Key>
          <Property Name="Id" Type="int" StoreGeneratedPattern="Identity" Nullable="false"/>
          <Property Name="Brand" Type="nvarchar(max)" Nullable="false"/>
          <Property Name="Model" Type="nvarchar(max)" Nullable="false"/>
          <Property Name="ReleaseDate" Type="datetime" Nullable="true"/>
        </EntityType>
        <EntityType Name="Drivers">
          <Key>
            <PropertyRef Name="Id"/>
          </Key>
          <Property Name="Id" Type="int" StoreGeneratedPattern="Identity" Nullable="false"/>
          <Property Name="Name" Type="nvarchar(max)" Nullable="false"/>
        </EntityType>
        <EntityType Name="CarDriver">
          <Key>
            <PropertyRef Name="Cars_Id"/>
            <PropertyRef Name="Drivers_Id"/>
          </Key>
          <Property Name="Cars_Id" Type="int" Nullable="false"/>
          <Property Name="Drivers_Id" Type="int" Nullable="false"/>
        </EntityType>
        <Association Name="FK_CarDriver_Car">
          <End Role="Car" Type="Ef2PlaygroundModel_3.Store.Cars" Multiplicity="1"/>
          <End Role="CarDriver" Type="Ef2PlaygroundModel_3.Store.CarDriver" Multiplicity="*"/>
          <ReferentialConstraint>
            <Principal Role="Car">
              <PropertyRef Name="Id"/>
            </Principal>
            <Dependent Role="CarDriver">
              <PropertyRef Name="Cars_Id"/>
            </Dependent>
          </ReferentialConstraint>
        </Association>
        <Association Name="FK_CarDriver_Driver">
          <End Role="CarDriver" Type="Ef2PlaygroundModel_3.Store.CarDriver" Multiplicity="*"/>
          <End Role="Driver" Type="Ef2PlaygroundModel_3.Store.Drivers" Multiplicity="1"/>
          <ReferentialConstraint>
            <Principal Role="Driver">
              <PropertyRef Name="Id"/>
            </Principal>
            <Dependent Role="CarDriver">
              <PropertyRef Name="Drivers_Id"/>
            </Dependent>
          </ReferentialConstraint>
        </Association>
      </Schema>
    </edmx:StorageModels>
    <!-- CSDL content -->
    <edmx:ConceptualModels>
      <Schema xmlns="http://schemas.microsoft.com/ado/2008/09/edm" xmlns:cg="http://schemas.microsoft.com/ado/2006/04/codegeneration" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" Namespace="Ef2PlaygroundModel_3" Alias="Self" xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation">
        <EntityContainer Name="Ef2PlaygroundModel_3Container" annotation:LazyLoadingEnabled="true">
          <EntitySet Name="Cars" EntityType="Ef2PlaygroundModel_3.Car"/>
          <EntitySet Name="Drivers" EntityType="Ef2PlaygroundModel_3.Driver"/>
          <AssociationSet Name="CarDriver" Association="Ef2PlaygroundModel_3.CarDriver">
            <End Role="Car" EntitySet="Cars"/>
            <End Role="Driver" EntitySet="Drivers"/>
          </AssociationSet>
        </EntityContainer>
        <EntityType Name="Car">
          <Key>
            <PropertyRef Name="Id"/>
          </Key>
          <Property Type="Int32" Name="Id" Nullable="false" annotation:StoreGeneratedPattern="Identity"/>
          <Property Type="String" Name="Brand" Nullable="false"/>
          <Property Type="String" Name="Model" Nullable="false"/>
          <Property Type="DateTime" Name="ReleaseDate" Nullable="true"/>
          <NavigationProperty Name="Drivers" Relationship="Ef2PlaygroundModel_3.CarDriver" FromRole="Car" ToRole="Driver"/>
        </EntityType>
        <EntityType Name="Driver">
          <Key>
            <PropertyRef Name="Id"/>
          </Key>
          <Property Type="Int32" Name="Id" Nullable="false" annotation:StoreGeneratedPattern="Identity"/>
          <Property Type="String" Name="Name" Nullable="false"/>
          <NavigationProperty Name="Cars" Relationship="Ef2PlaygroundModel_3.CarDriver" FromRole="Driver" ToRole="Car"/>
        </EntityType>
        <Association Name="CarDriver">
          <End Type="Ef2PlaygroundModel_3.Car" Role="Car" Multiplicity="*"/>
          <End Type="Ef2PlaygroundModel_3.Driver" Role="Driver" Multiplicity="*"/>
        </Association>
      </Schema>
    </edmx:ConceptualModels>
    <!-- C-S mapping content -->
    <edmx:Mappings>
      <Mapping Space="C-S" xmlns="http://schemas.microsoft.com/ado/2008/09/mapping/cs">
        <EntityContainerMapping StorageEntityContainer="Ef2PlaygroundModel_3StoreContainer" CdmEntityContainer="Ef2PlaygroundModel_3Container">
          <EntitySetMapping Name="Cars">
            <EntityTypeMapping TypeName="IsTypeOf(Ef2PlaygroundModel_3.Car)">
              <MappingFragment StoreEntitySet="Cars">
                <ScalarProperty Name="Id" ColumnName="Id"/>
                <ScalarProperty Name="Brand" ColumnName="Brand"/>
                <ScalarProperty Name="Model" ColumnName="Model"/>
                <ScalarProperty Name="ReleaseDate" ColumnName="ReleaseDate"/>
              </MappingFragment>
            </EntityTypeMapping>
          </EntitySetMapping>
          <EntitySetMapping Name="Drivers">
            <EntityTypeMapping TypeName="IsTypeOf(Ef2PlaygroundModel_3.Driver)">
              <MappingFragment StoreEntitySet="Drivers">
                <ScalarProperty Name="Id" ColumnName="Id"/>
                <ScalarProperty Name="Name" ColumnName="Name"/>
              </MappingFragment>
            </EntityTypeMapping>
          </EntitySetMapping>
          <AssociationSetMapping Name="CarDriver" TypeName="Ef2PlaygroundModel_3.CarDriver" StoreEntitySet="CarDriver">
            <EndProperty Name="Car">
              <ScalarProperty Name="Id" ColumnName="Cars_Id"/>
            </EndProperty>
            <EndProperty Name="Driver">
              <ScalarProperty Name="Id" ColumnName="Drivers_Id"/>
            </EndProperty>
          </AssociationSetMapping>
        </EntityContainerMapping>
      </Mapping>
    </edmx:Mappings>
  </edmx:Runtime>
  <!-- EF Designer content (DO NOT EDIT MANUALLY BELOW HERE) -->
  <edmx:Designer xmlns="http://schemas.microsoft.com/ado/2008/10/edmx">
    <edmx:Connection>
      <DesignerInfoPropertySet>
        <DesignerProperty Name="MetadataArtifactProcessing" Value="EmbedInOutputAssembly"/>
      </DesignerInfoPropertySet>
    </edmx:Connection>
    <edmx:Options>
      <DesignerInfoPropertySet>
        <DesignerProperty Name="ValidateOnBuild" Value="true"/>
        <DesignerProperty Name="EnablePluralization" Value="False"/>
        <DesignerProperty Name="CodeGenerationStrategy" Value="None"/>
      </DesignerInfoPropertySet>
    </edmx:Options>
    <!-- Diagram content (shape and connector positions) -->
    <edmx:Diagrams>
      <Diagram Name="Ef2PlaygroundModel_3">
        <EntityTypeShape EntityType="Ef2PlaygroundModel_3.Car" Width="1.5" PointX="3.25" PointY="1.625" Height="1.787985026041667"/>
        <EntityTypeShape EntityType="Ef2PlaygroundModel_3.Driver" Width="1.5" PointX="5.375" PointY="1.625" Height="1.59568359375"/>
        <AssociationConnector Association="Ef2PlaygroundModel_3.CarDriver">
          <ConnectorPoint PointX="4.75" PointY="2.422841796875"/>
          <ConnectorPoint PointX="5.375" PointY="2.422841796875"/>
        </AssociationConnector>
      </Diagram>
    </edmx:Diagrams>
  </edmx:Designer>
</edmx:Edmx>

app.config:

<configuration>
  <connectionStrings>
    <add 
      name="Ef2PlaygroundModel_3Container" 
      connectionString="metadata=res://*/Ef2PlaygroundModel_3.csdl|res://*/Ef2PlaygroundModel_3.ssdl|res://*/Ef2PlaygroundModel_3.msl;provider=System.Data.SqlClient;provider connection string=&quot;Data Source=.\SqlExpress;Initial Catalog=Ef2PlaygroundModel_3;Integrated Security=True;MultipleActiveResultSets=True&quot;" 
      providerName="System.Data.EntityClient" 
    />
  </connectionStrings>
</configuration>

Ef2PlaygroundModel_3Pocos.cs:

using System;
using System.Collections.Generic;
using System.Data.Objects;

namespace EF2_Playground
{
  public class Car
  {
    public Car()
    {
      Drivers = new List<Driver>();
    }

    public int Id { get; set; }
    public string Brand { get; set; }
    public string Model { get; set; }
    public DateTime? ReleaseDate { get; set; }

    public virtual List<Driver> Drivers { get; private set; }
  }

  public class Driver
  {
    public Driver()
    {
      Cars = new List<Car>();
    }

    public int Id { get; set; }
    public string Name { get; set; }

    public virtual List<Car> Cars { get; private set; }
  }

  public class Ef2PlaygroundModel_3Container : ObjectContext
  { 
    public Ef2PlaygroundModel_3Container()
      : base("name=Ef2PlaygroundModel_3Container") 
    {
      ContextOptions.LazyLoadingEnabled = true;
    }

    public IObjectSet<Car> Cars
    {
      get { return CreateObjectSet<Car>(); }
    }

    public IObjectSet<Driver> Drivers
    {
      get { return CreateObjectSet<Driver>(); }
    }
  }
}

Program.cs:

using System;

namespace EF2_Playground
{
  class Program
  {
    static void Main(string[] args)
    {
      using (var ctx = new Ef2PlaygroundModel_3Container())
      {
        foreach (var driver in ctx.Drivers)
        {
          Console.WriteLine(driver.Name);
          foreach (var car in driver.Cars)
          {
            Console.WriteLine("   drives a {0} - {1} (released on {2})", car.Brand, car.Model, car.ReleaseDate);
          }
        }
      }
    }
  }
}

And finally Model1.edmx that breaks the whole thing as soon as i add it to the project:

<?xml version="1.0" encoding="utf-8"?>
<edmx:Edmx Version="2.0" xmlns:edmx="http://schemas.microsoft.com/ado/2008/10/edmx">
  <!-- EF Runtime content -->
  <edmx:Runtime>
    <!-- SSDL content -->
    <edmx:StorageModels>
      <Schema xmlns="http://schemas.microsoft.com/ado/2009/02/edm/ssdl" Namespace="Model1.Store" Alias="Self" Provider="System.Data.SqlClient" ProviderManifestToken="2005">
        <EntityContainer Name="Model1TargetContainer">
        </EntityContainer>
      </Schema>
    </edmx:StorageModels>
    <!-- CSDL content -->
    <edmx:ConceptualModels>
      <Schema xmlns="http://schemas.microsoft.com/ado/2008/09/edm" xmlns:cg="http://schemas.microsoft.com/ado/2006/04/codegeneration" xmlns:store="http://schemas.microsoft.com/ado/2007/12/edm/EntityStoreSchemaGenerator" Namespace="Model1" Alias="Self" xmlns:annotation="http://schemas.microsoft.com/ado/2009/02/edm/annotation">
        <EntityContainer Name="Model1Container" annotation:LazyLoadingEnabled="true">
        </EntityContainer>
      </Schema>
    </edmx:ConceptualModels>
    <!-- C-S mapping content -->
    <edmx:Mappings>
      <Mapping xmlns="http://schemas.microsoft.com/ado/2008/09/mapping/cs" Space="C-S">
        <Alias Key="Model" Value="Model1"/>
        <Alias Key="Target" Value="Model1.Store"/>
        <EntityContainerMapping CdmEntityContainer="Model1Container" StorageEntityContainer="Model1TargetContainer">
        </EntityContainerMapping>
      </Mapping>
    </edmx:Mappings>
  </edmx:Runtime>
  <!-- EF Designer content (DO NOT EDIT MANUALLY BELOW HERE) -->
  <edmx:Designer xmlns="http://schemas.microsoft.com/ado/2008/10/edmx">
    <edmx:Connection>
      <DesignerInfoPropertySet>
        <DesignerProperty Name="MetadataArtifactProcessing" Value="EmbedInOutputAssembly"/>
      </DesignerInfoPropertySet>
    </edmx:Connection>
    <edmx:Options>
      <DesignerInfoPropertySet>
        <DesignerProperty Name="ValidateOnBuild" Value="true"/>
        <DesignerProperty Name="EnablePluralization" Value="False"/>
      </DesignerInfoPropertySet>
    </edmx:Options>
    <!-- Diagram content (shape and connector positions) -->
    <edmx:Diagrams>
      <Diagram Name="Model1"/>
    </edmx:Diagrams>
  </edmx:Designer>
</edmx:Edmx>

Answer 1

Ok, i guess i've got it. I reduced the second model (the one that brakes the project) to the following:

Class1.cs

using System.Data.Objects.DataClasses;
[assembly: EdmSchemaAttribute()]

Bang! The well known exception appears.

As in so many cases, reading the documentation helps:

Mapping POCO entities is not supported if any mapping attributes are applied to custom data classes, including EdmSchemaAttribute at the assembly level.

Sure, i do not literally add mapping attributes to CUSTOM data classes but that doesn't matter for the EdmSchemaAttribute since that one lives on the assembly level.

Adding the second non-POCO model causes code generation resulting in a class that contains (at least) the EdmSchemaAttribute and that is not supported.

What i've learned: Don't mix POCO and non-POCO models in one assembly.