c# - NHibernate LINQ projection using helper class -

i'm trying add projection nhibernate linq query (via .select()), since have bit of logic want use helper class rather returning projected model directly.

my code looks (shortened):

var query = session.query<messageinstance>(); ... (a few .fetch , .thenfetch calls) var result = query.where(specification.issatisfiedby())                   .orderby(m => m.creationdate)                   .select(m => _messagemodelhelper.buildmessagemodel(m)); 

_messagemodelhelper object transforms messageinstance object messagemodel , contains logic handle different scenarios, since depends on related entities.

this fails error:

field dal.repositories.messagerepository._messagemodelhelper' not defined type 'nhibernate.linq.nhqueryable`1 [domain.entities.message]'

if avoid using field (which necessary di), , this:

.select(m => new messagemodelhelper().buildmessagemodel(m)) 

i system.notsupportedexception.

it appears approach won't work. can do, while avoiding need return new messagemodel directly? need keep projection, can't operate on enumerable.

you have call buildmessagemodel() "locally":

var result = query.where(specification.issatisfiedby())                   .orderby(m => m.creationdate)                   .asenumerable() // point onward query                                   // executed c#-side                   .select(m => _messagemodelhelper.buildmessagemodel(m)); 

note that, written, won't sql projection, full object selected db.