Demo for http://stackoverflow.com/questions/9136923/eager-loading-in-entityframework-with-dbcontext-database-sqlquery

gistfile1.cs

using System.Collections.Generic;
using System.ComponentModel.DataAnnotations.Schema;
using System.Data.Common;
using System.Data.Entity;
using System.Linq;
using Npgsql;

namespace ConsoleApplication1
{
    [Table("books", Schema = "public")]
    public class book
    {
        public int id { get; set; }
        public string name { get; set; }
        public int author_id { get; set; }
        [ForeignKey("author_id")]
        public virtual author Author { get; set; }
    }

    [Table("authors", Schema = "public")]
    public class author
    {

        public int id { get; set; }
        public string name { get; set; }
        public virtual ICollection<book> Books { get; set; }
    }

    class Program
    {
        class c : DbContext
        {
            public IDbSet<book> Books { get; set; } 
            public IDbSet<author> Authors { get; set; }

            public c(DbConnection existingConnection, bool contextOwnsConnection) : base(existingConnection, contextOwnsConnection)
            {
            }

        }

        static void Main(string[] args)
        {
            var csb = new NpgsqlConnectionStringBuilder();
            csb.Host = "localhost";
            csb.Port = 5432;
            csb.UserName = "postgres";
            csb.Password = "z";

            using (var c = new c(new NpgsqlConnection(csb.ConnectionString), true))
            {
                // both entities are no-tracking
                var bookFromSet = c.Set<book>().SqlQuery("select * from books").AsNoTracking().First();
                var bookFromDatabase = c.Database.SqlQuery<book>("select * from books").First();
                // this is not null, as expected
                var authorFromSet = bookFromSet.Author;
                // this is strangely null, I cannot find this behavior documented...
                var authorFromDatabase = bookFromDatabase.Author;
            }
        }

    }
}