(repost updated)

Imagine I have (pseudo tables)

A
{
    Id,
    SomeDate Date
}

B
{
    A.Id,
    C.Id
}

C
{
    Id
}

D
{
    C.Id,
    StartDate Date,
    EndDate Date,
}

A and C is many to many relation through B, C and D is one to many relation.

Now I'd like to fetch A and prefetch D, like pseudo

A.WithPath(aPath => aPath
  .Prefetch<CEntity>(a => a.CCollectionViaB)
     .SubPath(cp => cp
        .Prefetch<DEntity>(c => c.D)
              .FilterOn(only D where A.SomeDate between D.StartDate and D.EndDate)
)

The problem is FilterOn where I can't reach A.SomeDate.

v3.5 17.1.2013

I think you are trying to filter a prefetch query as if it was a joined query. That's not how prefetchs are meant to be used. These queries are not joined with the root entity.

To achieve what you want you will need to treat it as a separate quer, i.e. join with A and use fields from A in filtering.

Walaa wrote:

I think you are trying to filter a prefetch query as if it was a joined query. That's not how prefetchs are meant to be used. These queries are not joined with the root entity.

To achieve what you want you will need to treat it as a separate quer, i.e. join with A and use fields from A in filtering.

Yep, that's what I could do but then I'd loose entities. But yes, that's a possible way.

In theory, another way would be:

A.WithPath(aPath => aPath
.Prefetch<CEntity>(a => a.CCollectionViaB)
     .SubPath(cp => cp
        .Prefetch<DEntity>(c => c.D)
             .FilterOn(d => d.C.Bs.Where(b => b.A.SomeDate >= d.StartDate 
                                                              && b.A.SomeDate <= d.EndDate).Count() > 0
                                            
                          )
      )

I used it here: http://www.llblgening.com/archive/2009/10/prefetchpaths-in-depth/#filteringandsorting In my example It's just two levels and I used discrete values, but it should work.

Hi dealmo,

Yep, that does the trick. I could have thought of that before I greatly improved it though by substituting Count() > 0 with Any()