Schema invalid and types cannot be loaded because the assembly contains EdmSchemaAttribute - entity-framework

Question

Getting the following error:
Schema specified is not valid. Errors:
The types in the assembly 'x, Version=1.0.0.0, Culture=neutral,
PublicKeyToken=null' cannot be loaded because the assembly contains
the EdmSchemaAttribute, and the closure of types is being loaded by
name. Loading by both name and attribute is not allowed.
What does this error mean exactly?
I'm trying to shoe-horn into my application an EF model from an existing database.
Before this application was based on CodeFirst and using the repository pattern but for the life of me I can't get this working.
Before I had:
public class BaseModelContext : DbContext
{
public DbSet<User> Users { get; set; }
public DbSet<Role> Roles { get; set; }
}
But in a EF model-first scenario (one where tables already exist in the db), I had to remove these as it didn't seem to like having a repository pattern on DbSet properties.
So I stripped these out, and the repository can then use repository on the classes already defined on the .designer.cs context class (the EF model). This has the EdmSchemaAttribute set inside the generated code.
So how do I get my repository pattern to work in the model-first scenario? What does the above error mean exactly?
EDIT
Added new code:
public class BaseModelContext : DbContext
{
// public DbSet<Location> Locations { get; set; }
public BaseModelContext(string nameOrConnection)
: base(nameOrConnection)
{
}
public BaseModelContext()
{
}
}
public class VisitoriDataContext : BaseModelContext
{
public VisitoriDataContext()
: base("visitoriDataConnection")
{
}
}
public interface IVisitoriDataContextProvider
{
VisitoriDataContext DataContext { get; }
}
public class VisitoriDataContextProvider : IVisitoriDataContextProvider
{
public VisitoriDataContext DataContext { get; private set; }
public VisitoriDataContextProvider()
{
DataContext = new VisitoriDataContext();
}
}
public class VisitoriRepository<T> : IRepository<T> where T : class
{
protected readonly IVisitoriDataContextProvider _ctx;
public VisitoriRepository(IVisitoriDataContextProvider ctx)
{
_ctx = ctx;
}
public T Get(int id)
{
return _ctx.DataContext.Set<T>().Find(id);
}
}
public interface ILocationRepo : IRepository<Location>
{
IEnumerable<Location> GetSuggestedLocationsByPrefix(string searchPrefix);
}
public class LocationRepo : VisitoriRepository<Location>, ILocationRepo
{
public LocationRepo(IVisitoriDataContextProvider ctx)
: base(ctx)
{
}
public IEnumerable<Location> GetSuggestedLocationsByPrefix(string searchPrefix)
{
return Where(l => l.name.Contains(searchPrefix)).ToList();
}
}

Answer 1

The error means that you cannot combine code first mapping (data annotations and fluent API) and EDMX mapping (with EntityObjects!) for entity with the same name. These two approaches are disjunctive.
The rest of your question is not clear.
Btw. building mapping from existing database is called database first not model first.

Answer 2

Decorate the assembly containing the GILayerModel type with [assembly: EdmSchema] attribute.

Answer 3

In my case, I had a class that derived from an entity (code-first class) in another assembly, and I was adding an instance of this class to the DBContext:
in DBEntities project:
public class GISLayer
{
[Key]
[DatabaseGenerated(System.ComponentModel.DataAnnotations.Schema.DatabaseGeneratedOption.Identity)]
public int GISLayerId { get; set; }
[StringLength(200)]
public string LayerName { get; set; }
public List<GISNode> Nodes { get; set; }
}
in the second assembly:
public class GISLayerModel : DBEntities.GISLayer
{
public new List<GISNodeModel> NodesModel { get; set; }
}
and the cause of error:
[WebMethod]
public void SaveGISLayers(GISLayerModel[] layers)
{
using (DBEntities.DBEntities db = new DBEntities.DBEntities())
{
foreach (var l in layers)
{
if (l.GISLayerId > 0)
{
db.GISLayers.Attach(l); //attaching a derived class
db.Entry(l).State = System.Data.EntityState.Modified;
}
else
db.GISLayers.Add(l); //adding a derived class
SaveGISNodes(l.NodesModel.ToArray(), db);
}
db.SaveChanges();
}
}
So, I used AutoMapper to copy properties of derived class to a new instance of base class:
DBEntities.GISLayer gl = AutoMapper.Mapper.Map<DBEntities.GISLayer>(l);
if (gl.GISLayerId > 0)
{
db.GISLayers.Attach(gl);
db.Entry(gl).State = System.Data.EntityState.Modified;
}
else
db.GISLayers.Add(gl);
That solved the problem.