NpgSql, EF6, NTS: EntityType 'Point' has no key defined

Question

I'm working on a simple import tool written in C# for .NET Framework 4.7 to read a MS-Access file and save it to a PostGIS database.

I'm having trouble letting EF6 now my Point object is a NetTopology class and not another table.

When I read of write my data from my PostGIS database I get this error:

System.Data.Entity.ModelConfiguration.ModelValidationException
  HResult=0x80131500
  Message=One or more validation errors were detected during model generation:

Importer.Point: : EntityType 'Point' has no key defined. Define the key for this EntityType.
Points: EntityType: EntitySet 'Points' is based on type 'Point' that has no keys defined.

Here is some code:

    public static void Main(string[] args)
    {
        // Place this at the beginning of your program to use NetTopologySuite everywhere (recommended)
        NpgsqlConnection.GlobalTypeMapper.UseNetTopologySuite();

        using (var context = new PostGisContext())
        {
            var newKey = context.MyLocations.Count();
        }
    }

context.MyLocations.Count() is throwing the error.

public class PostGisContext : DbContext
{
    public DbSet<MyLocation> MyLocations { get; set; }

    public PostGisContext() : base("name=PostgreSql")
    {        }

    protected override void OnModelCreating(DbModelBuilder modelBuilder)
    {
        // PostgreSQL uses the data schema by default - not dbo.
        modelBuilder.HasDefaultSchema("data");

        // Don't use plural table names:
        modelBuilder.Conventions.Remove<PluralizingTableNameConvention>();

        // Change CamelCase to lower-case:
        modelBuilder.Types().Configure(c => c.ToTable(LowerCaseTableName(c.ClrType)));

        modelBuilder.Conventions.Add(new LowerCaseConvention());

        base.OnModelCreating(modelBuilder);
    }

    private static string LowerCaseTableName(Type type)
    {
        var result = Regex.Replace(type.Name, ".[A-Z]", m => m.Value[0] + "_" + m.Value[1]);

        return result.ToLower();
    }
}

// A custom convention.
internal class LowerCaseConvention : IStoreModelConvention<EdmProperty>
{
    public void Apply(EdmProperty property, DbModel model)
    {
        property.Name = Regex.Replace(property.Name, ".[A-Z]", m => m.Value[0] + "_" + m.Value[1]).ToLower();
    }
}

When changing the Location column to string the above code works fine.

public class MyLocation
{
    [Key] 
    public int Id { get; set; }
    public string LocationId { get; set; }
    public NetTopologySuite.Geometries.Point Location { get; set; }
} 

public class NpgSqlConfiguration : DbConfiguration
{
    public NpgSqlConfiguration()
    {
        const string name = "Npgsql";

        SetProviderFactory(providerInvariantName: name, 
            providerFactory: NpgsqlFactory.Instance);

        SetProviderServices(providerInvariantName: name, 
            provider: NpgsqlServices.Instance);

        SetDefaultConnectionFactory(connectionFactory: new NpgsqlConnectionFactory());
    }
}

I must be forgetting a setting or something, but I can't find it. Any help will be much appreciated.

Answer 1

NetTopologySuite and PostGIS aren't supported in Entity Framework 6, only in Entity Framework Core. This is because EF6's type system is closed and does not allow for flexible provider-specific extensions in the way that EF Core does.