The session-management. How you are managing the NH's session ? The session shouldn't be closed during page rendering... more exactly... the session shouldn't be closed before the end of the request.
2010/3/15 SedulousTurtle <[email protected]> > Sorry, I didn't mean to imply that there was a bug in NHibernate... > > I'm sure I do have a few things wrong in my the code, but I don't know > what they are, and I'm sure I'm misunderstanding some things, but I > don't know what they are. Can you kindly elaborate about how I'm > messing up? > > Brian > > On Mar 15, 4:42 pm, Fabio Maulo <[email protected]> wrote: > > Your problem is not lazy loading but the session-management (well... only > to > > give mention to one) and the bug is there for sure but in your > application > > and not in NHibernate. > > > > 2010/3/15 SedulousTurtle <[email protected]> > > > > > > > > > > > > > And I should also note: of course, using lazy="false" in the > > > Institution class mapping > > > (as in: <class name="Institution" lazy="false">) > > > keeps the exception from being thrown...but I can't make this the > > > default fix whenever I get a bug like this! > > > > > On Mar 15, 4:16 pm, SedulousTurtle <[email protected]> > > > wrote: > > > > Hi List, > > > > > > I'm responsible for looking at NHibernate as a potential DB solution > > > > on our next product release -- but I'm having trouble getting my > > > > prototype to work properly. In a few cases, I'm getting perplexing > > > > behaviour associated with lazy loading and proxies. I suspect that > > > > these are all occuring because I have some error in my understanding > > > > of how these work. > > > > > > Here's my first problem. I'm encountering a > > > > LazyInitializationException when my WebApp testing front end tries to > > > > display a DataGrid with information about objects of type Instrument. > > > > > > ---------------- Application information ------------------ > > > > The application manages electronic medical instruments in a hospital. > > > > > > Part of our object system is a heiarchy of parent/child relationships > > > > (parent owns a collection of children; children have a reference to > > > > their parent; I don't think either end is set inverse="true") > > > > > > Institution (e.g. Springfield Hospital) > > > > Location (e.g. Emergency Room) > > > > Instrument > > > > > > Institution and Location are effectively "virtual" classes (though > > > > they're not explicitly marked as such); they each have 2 subclasses > > > > that are used in the database. > > > > > > References in the source code to other objects such as > > > > HealthCareSystem and Method are unimportant. > > > > > > ------------------------------------ Source Code > > > > ------------------------------------------- > > > > <Locations.aspx.cs> > > > > ... > > > > private void BindInstrumentGrid() > > > > { > > > > ... > > > > > > grInstr.DataSource = > > > > Facade.InstLoc.GetInstruments(<various parameters>); > > > > grInstr.DataBind(); > > > > } > > > > > > <InstrumentFacade.cs> > > > > ... > > > > public IList GetInstruments(<various parameters>) > > > > { > > > > IList<Instrument> instrumentList; > > > > ... > > > > > > using (ISession ses = NHibernateHelper.OpenSession()) > > > > using (ses.BeginTransaction()) > > > > { > > > > instrumentList = ses.CreateQuery( > > > > @"SELECT instr FROM Instrument AS instr > > > > JOIN instr.Method AS md > > > > JOIN md.Method AS meth > > > > JOIN instr.Location AS loc > > > > JOIN loc.Institution AS instit > > > > JOIN instit.HCSystem AS hcs > > > > WHERE meth.Name=:method_name > > > > AND loc.Name=:location_name > > > > AND instit.Name=:institution_name > > > > AND hcs.Name=:healthcaresystem_name") > > > > .SetString("method_name", methodName) > > > > .SetString("location_name", asLocationName) > > > > .SetString("institution_name", asInstName) > > > > .SetString("healthcaresystem_name", > > > > asHCSystemName) > > > > .List<Instrument>(); > > > > > > foreach (Instrument i in instrumentList) > > > > { > > > > NHibernateUtil.Initialize(i.Location); > > > > > NHibernateUtil.Initialize(i.Location.Institution); > > > > } > > > > > > ses.Transaction.Commit(); > > > > } > > > > return instrumentList.ToList(); > > > > } > > > > ... > > > > > > ---------------------------------------------------------------------------------------------------- > > > > > > On application execution, when BindInstrumentGrid() executes > > > > "grInstr.DataBind();" I get the following NHibernate exception: > > > > "Initializing[TestRecordProto.Domain.Institution#2]-Could not > > > > initialize proxy - no Session." > > > > > > I partially understand why I'm getting this error, because I'm seeing > > > > weird behavior during NHibernateUtil.Initialize() when I run in debug > > > > mode. Initially, i.Location is of type LocationProxy -- with its > only > > > > set property being "string Name". All other properties, including > the > > > > int ID, is uninitialized. But after "Initialize(i.Location)", I > would > > > > expect i.Location proxy would be replaced with a real object of type > > > > Location. But it is not in fact replaced -- the reference is left as > > > > a proxy, and its properties do not change! And of course then > > > > "Initialize(i.Location.Institution)" can not really initialize the > > > > Institution field -- because i.Location.Institution is null, because > > > > i.Location is a proxy without instantiated properties! > > > > > > So I don't know what I'm doing wrong -- I'm supposed to call > > > > Initialize() on the referenced objects that I'll need to access after > > > > the session is closed -- and yet Initialize() isn't solving the > > > > problem for me. Why does this happen? > > > > > > The information in the database all looks correct, with the correct > > > > links between these objects. I have 1 record saved of type > > > > Instrument, which is linked by foreign key to a valid Location, which > > > > is linked by foreign key to a valid Institution. > > > > > > Thank you in advance. > > > > > -- > > > You received this message because you are subscribed to the Google > Groups > > > "nhusers" group. > > > To post to this group, send email to [email protected]. > > > To unsubscribe from this group, send email to > > > [email protected]<nhusers%[email protected]> > <nhusers%[email protected]<nhusers%[email protected]> > > > > > . > > > For more options, visit this group at > > >http://groups.google.com/group/nhusers?hl=en. > > > > -- > > Fabio Maulo- Hide quoted text - > > > > - Show quoted text - > > -- > You received this message because you are subscribed to the Google Groups > "nhusers" group. > To post to this group, send email to [email protected]. > To unsubscribe from this group, send email to > [email protected]<nhusers%[email protected]> > . > For more options, visit this group at > http://groups.google.com/group/nhusers?hl=en. > > -- Fabio Maulo -- You received this message because you are subscribed to the Google Groups "nhusers" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/nhusers?hl=en.
