3
votes

Despite setting up mapping to be Not.Nullable() and Not.LazyLoad()

For some reason NH is joining a table twice, once with a INNER JOIN to appease the WHERE, and secondly on a OUTER JOIN to select the data.

Surely, as we've already JOINED the data, it would make sense to just use the joined table...

SELECT
     ...Tables..
from Tasks taskentity0_,
 outer Cases caseentity1_,
 outer Grades gradeentit2_,
 Cases caseentity5_ 
WHERE
....

My LINQ query for this is:

IQueryable<TaskEntity> tasks = TaskRepo.Find(
    t => t.DueDate <= DateTime.Now
      && (t.TaskInitials == userInitials || (t.TaskInitials == "" || t.TaskInitials == null))
      && t.Team.GST.Any
                    (x => x.Initials == userInitials
                        && x.WorkType.WorkTypeCode == t.WorkType.WorkTypeCode
                        && x.Team.TeamCode == t.Team.TeamCode
                    )
      && (t.Case.CaseOnHold <= DateTime.Now || t.Case.CaseOnHold == null || (t.SingleTask == "M" || t.SingleTask == "m"))
      && (t.Case.CaseMatter.StartsWith("0") || t.Case.CaseMatter.StartsWith("9"))
                ).Fetch(t => t.Case,FetchProvider)

My Reference Mapping:

        References(x => x.Case).Column("ta_c_ref").Not.Nullable();

Thoughts?

We are using the repository pattern, and have reimplemented the Fetch extension method to work this way (Hence passing the FetchProvider in).

Also, QueryOver<T> is not an option here as we require IQueryables..

I am using NH 3.1.

For the masses:

We no longer use the Fetch or LINQ, we moved to HQL...

    /// <summary>
    /// Interfaces for Fetch() statements
    /// </summary>

    public interface IFetchingProvider
    {
        IFetchRequest<TOriginating, TRelated> Fetch<TOriginating, TRelated>(IQueryable<TOriginating> query, Expression<Func<TOriginating, TRelated>> relatedObjectSelector);

        IFetchRequest<TOriginating, TRelated> FetchMany<TOriginating, TRelated>(IQueryable<TOriginating> query, Expression<Func<TOriginating, IEnumerable<TRelated>>> relatedObjectSelector);

        IFetchRequest<TQueried, TRelated> ThenFetch<TQueried, TFetch, TRelated>(IFetchRequest<TQueried, TFetch> query, Expression<Func<TFetch, TRelated>> relatedObjectSelector);

        IFetchRequest<TQueried, TRelated> ThenFetchMany<TQueried, TFetch, TRelated>(IFetchRequest<TQueried, TFetch> query, Expression<Func<TFetch, IEnumerable<TRelated>>> relatedObjectSelector);
    }


public class NhFetchingProvider : IFetchingProvider
    {
        public IFetchRequest<TOriginating, TRelated> Fetch<TOriginating, TRelated>(IQueryable<TOriginating> query, Expression<Func<TOriginating, TRelated>> relatedObjectSelector)
        {
            var fetch = EagerFetchingExtensionMethods.Fetch(query, relatedObjectSelector);
            return new FetchRequest<TOriginating, TRelated>(fetch);
        }

        public IFetchRequest<TOriginating, TRelated> FetchMany<TOriginating, TRelated>(IQueryable<TOriginating> query, Expression<Func<TOriginating, IEnumerable<TRelated>>> relatedObjectSelector)
        {
            var fecth = EagerFetchingExtensionMethods.FetchMany(query, relatedObjectSelector);
            return new FetchRequest<TOriginating, TRelated>(fecth);
        }

        public IFetchRequest<TQueried, TRelated> ThenFetch<TQueried, TFetch, TRelated>(IFetchRequest<TQueried, TFetch> query, Expression<Func<TFetch, TRelated>> relatedObjectSelector)
        {
            var impl = query as FetchRequest<TQueried, TFetch>;
            var fetch = EagerFetchingExtensionMethods.ThenFetch(impl.NhFetchRequest, relatedObjectSelector);
            return new FetchRequest<TQueried, TRelated>(fetch);
        }

        public IFetchRequest<TQueried, TRelated> ThenFetchMany<TQueried, TFetch, TRelated>(IFetchRequest<TQueried, TFetch> query, Expression<Func<TFetch, IEnumerable<TRelated>>> relatedObjectSelector)
        {
            var impl = query as FetchRequest<TQueried, TFetch>;
            var fetch = EagerFetchingExtensionMethods.ThenFetchMany(impl.NhFetchRequest, relatedObjectSelector);
            return new FetchRequest<TQueried, TRelated>(fetch);
        }
}

public static IFetchRequest<TOriginating, TRelated> Fetch<TOriginating, TRelated>(this IQueryable<TOriginating> query, Expression<Func<TOriginating, TRelated>> relatedObjectSelector, Func<IFetchingProvider> FetchingProvider)
        {
            return FetchingProvider().Fetch(query, relatedObjectSelector);
        }
2
The repository pattern kills the functionality of NHibernate. My opinion and many others share the same thought.CrazyCoderz
It would be helpful to see the Fetch extension source code..Hoghweed
Updated from history - bare in mind, that code is now nearly a year old and not used.Stuart.Sklinar

2 Answers

0
votes

Using inner joins with linq in NHibernate isn't supported yet. more info can be found here: https://nhibernate.jira.com/browse/NH-2790