Nhibernate generating OUTER JOIN for a fetch
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 IQueryable s..
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);
}
Using inner joins with linq in NHibernate isn't supported yet. more info can be found here: https://nhibernate.jira.com/browse/NH-2790
I've added support for it!!
https://www.nuget.org/packages/NHibernate.Linq.InnerJoinFetch
Enjoy!!!
链接地址: http://www.djcxy.com/p/60998.html