EF DbContext-derived (Code-First) context exposing only collection property that .Include() underlying navigational property.

gistfile1.cs

 public class MyContext : DbContext
    {
        protected virtual IDbSet<Field> InnerFields
        {
            get { return base.Set<Field>(); }
        }

        protected virtual IDbSet<DimensionDefinition> InnerDimensionDefinitions
        {
            get { return base.Set<DimensionDefinition>(); }
        }
                
        public IQueryable<Field> Fields
        {
            get { return InnerFields.Include(x => x.Dimensions.Select(y => y.DimensionValue)); }
        }

        public MyContext()
            :base("MyContext")
        {
        }

        protected override void OnModelCreating(DbModelBuilder modelBuilder)
        {
            base.OnModelCreating(modelBuilder);
            modelBuilder.Entity<DimensionValue>().ToTable(typeof(DimensionValue).Name);
            modelBuilder.Entity<Field>().ToTable(typeof(Field).Name);
            modelBuilder.Entity<DimensionDefinition>().ToTable(typeof(DimensionDefinition).Name);
            modelBuilder.Entity<FieldDefinition>().ToTable(typeof(FieldDefinition).Name);
        }

        public void AddDimensionDefinition(DimensionDefinition dimensionDefinition)
        {
            if (dimensionDefinition == null) throw new ArgumentNullException("dimensionDefinition");

            InnerDimensionDefinitions.Add(dimensionDefinition);
        }

        public void AddField(Field field)
        {
            if (field == null) throw new ArgumentNullException("field");

            InnerFields.Add(field);
        }
    }