Entity Framework - Eagerly load object graph using stored procedures

Question

Background

I am changing my LINQ-to-SQL code in my project to Entity Framework. Most of the change over was relatively simple, however, I have run into

Answer 1

It can be done in a fairly simple way but takes some manual effort. Here is an MSDN post on handling stored procedures with multiple result sets which shows both a code first and database first approach.

Example:

Load EntityB proc:

create proc dbo.Get_EntityB_by_EntityAId( @aId int )
as

select distinct
    b.EntityBId
    , b.Description
from
    EntityA a
    left outer join EntityB b
     on a.PrimaryEntityB_EntityBId = b.EntityBId
    left outer join EntityB b2
     on a.AlternativeEntityB_EntityBId = b2.EntityBId
where
    a.EntityAId = @aId
go

Load EntityA proc (which calls load B proc)

create proc dbo.Get_EntityA_by_Id( @id int )
as

-- use a select statement
select 
    a.EntityAId
    , a.Description
    , a.PrimaryEntityB_EntityBId
    , a.AlternativeEntityB_EntityBId
from
    EntityA a
where
    a.EntityAId = @id

-- and/or other sprocs
exec dbo.Get_EntityB_by_EntityAId @id

go

Entity classes

[Table("EntityA")]
public partial class EntityA
{
    public int EntityAId { get; set; }
    public string Description { get; set; }


    public virtual EntityB PrimaryEntityB { get; set; }

    public virtual EntityB AlternativeEntityB { get; set; }
}


[Table("EntityB")]
public partial class EntityB
{
    public int EntityBId { get; set; }
    public string Description { get; set; }

    [InverseProperty("PrimaryEntityB")]
    public virtual ICollection EntityAsViaPrimary { get; set; }
    [InverseProperty( "AlternativeEntityB" )]
    public virtual ICollection EntityAsViaAlternative { get; set; }
}

Method that calls sproc and handles results (for this method, you could return the one EntityA if you'd like)

public static void EagerLoadEntityA( int aId )
{
    using( var db = new TestEntities() )
    {
        // if using code first
        db.Database.Initialize( false );

        var cmd = db.Database.Connection.CreateCommand();
        cmd.CommandText = "dbo.Get_EntityA_by_Id";

        db.Database.Connection.Open();

        try
        {
            var reader = cmd.ExecuteReader();

            var objContext = ( ( IObjectContextAdapter )db ).ObjectContext;

            var aEntities = objContext
                .Translate( reader, "EntityAs", MergeOption.AppendOnly );

            reader.NextResult();

            var bEntities = objContext
                .Translate( reader, "EntityBs", MergeOption.AppendOnly );

        }
        finally
        {
            db.Database.Connection.Close();
        }
    }
}

Usage:

EagerLoadEntityA( 1234 );
var entityA = db.EntityAs.Find( 1234 ); // cached
var primB = entityA.PrimaryEntityB; // this is already loaded