EF Including Other Entities (Generic Repository pattern)

Say goodbye to the hardcoded ObjectQuery(T).Include calls

If you're using EF > 4, then it's built in, check DbExtensions.Include on MSDN.

//I have included the bare minimum here. Below is how to use it.

     IQueryable<File> xg= UnitOfWork.Files.GetAllLazyLoad(d => d.FileId == 1, 
            r => r.FileCategory);
//where r.FileCategory is a navigational property.

//Interface


    namespace Msh.Intranet.Repository.GenericRepoPattern
    {
        public interface IRepository<T> where T:class
        {

            IQueryable<T> GetAllLazyLoad(Expression<Func<T, bool>> filter, params Expression<Func<T, object>>[] children);

        }
    }



        namespace Msh.Intranet.Repository.GenericRepoPattern
        {
            /// <summary>
            /// The EF-dependent, generic repository for data access
            /// </summary>
            /// <typeparam name="T">Type of entity for this Repository.</typeparam>
            public class EFRepository<T> : IRepository<T> where T : class
            {
                public EFRepository(DbContext dbContext)
                {
                    if (dbContext == null)
                        throw new ArgumentNullException("dbContext");
                    DbContext = dbContext;
                    DbSet = DbContext.Set<T>();

                }

                protected DbContext DbContext { get; set; }

                protected DbSet<T> DbSet { get; set; }


                public virtual IQueryable<T> GetAllLazyLoad(Expression<Func<T, bool>> filter, params Expression<Func<T, object>>[] children) 
                {


                        children.ToList().ForEach(x=>DbSet.Include(x).Load());
                        return DbSet;
                }

            }
        }

Use just the Include extension on IQueryable. It is available in EF 4.1 assembly. If you don't want to reference that assembly in your upper layers create wrapper extension method in your data access assembly.

Here you have example:

public static IQueryable<T> IncludeMultiple<T>(this IQueryable<T> query, params Expression<Func<T, object>>[] includes)
    where T : class
{
    if (includes != null)
    {
        query = includes.Aggregate(query, 
                  (current, include) => current.Include(include));
    }

    return query;
}

You will use it for example like:

var query = context.Customers
                   .IncludeMultiple(
                       c => c.Address,
                       c => c.Orders.Select(o => o.OrderItems));

This query will load all customers with their addresses and orders and every order will contain its order items.