I won't "overrule" Oren's answer :-), but in NH 2.x Linq is built on top of the Criteria API, and it supports caching.
Google "effectus nhibernate" and "chinook nhibernate" and you'll get the relevant results at the top (don't make me use lmgtfy) I don't think NH is hard to use at all, but it does have a learning curve. Fortunately, there are lots of examples, documentation (not the best in the world, but it's ok) and this great community that's always willing to help in the forums, stackoverflow, and the blogs of Fabio, Oren, José and others. Diego On Fri, Feb 12, 2010 at 11:38, CSLem <[email protected]> wrote: > So, this is where I get confused. Much of the info published in > various sites on the web and even in this forum conflict. I initially > set my app up using straight NHibernate and was using (or abusing?) > the cache trying to implement some of my requirements. When > Linq2NHibernate was released I moved to that because it seemed the > queries would be easier for others who are even less familiar with > NHibernate to maintain since they are already using Linq. The cache > was not performing as I had expected after that so I sent a question > to Oren who said the cache was not available in Linq2NH. Putting > costly queries into the cache does not appear to be an option for me. > And even the Linq2NH appears to do odd things since a simple lambda > appears to grab the entire list and filter rather than passing the > filter to SQL. I have yet to even tackle tracking that down. > > I guess my point is that there are so many ways to approach a given > problem it is very easy to be sidetracked with a single statement that > heads you off in the wrong direction for your specific project. > > On that note...trying googling Effectus and Chinook and you will see > why it can be hard to find pertinent information. > > I don't mean this as a grouse...just venting frustration over trying > to use what appears to be a good tool to implement some ugly > requirements and finding it very difficult to plow through. > > On Feb 12, 8:15 am, Diego Mijelshon <[email protected]> wrote: > > John,... > > > > read more » > > > > Yes, it's a NH session per web request. > > Storing NHibernate sessions in ASP.NET sessions is a terrible, terrible > > idea. > > Why would you want to "hold data in session" across web requests?? That > > basically kills your scalability. > > If you are concerned about costly queries, that's what the 2nd level > cache > > is for. > > > > Diego > > > > > > > > On Fri, Feb 12, 2010 at 10:05, John Davidson <[email protected]> > wrote: > > > Diego > > > > > You say web app pattern is NHibernate session per request. Is that each > > > page request? > > > > > Or do you mean that web pattern should be NHibernate session per User > web > > > session? > > > > > The latter allows NHibernate to effectively hold data in session across > web > > > requests, and only has an additional cost when the web session is > abandoned > > > by the user without the apps knowledge, though the session will expire > after > > > 20 minutes(defualt). > > > > > John Davidson > > > > > On Thu, Feb 11, 2010 at 7:59 PM, Diego Mijelshon < > [email protected]>wrote: > > > > >> In a web app, the usual pattern is session per request. > > > > >> You should research existing samples with patterns for web and desktop > > >> apps (which are very different) before reinventing the wheel and > investing > > >> in an architecture that will bite you later. > > >> Just sayin'. > > > > >> For desktop, two interesting approaches are Effectus and Chinook. > > > > >> Diego > > > > >> On Thu, Feb 11, 2010 at 21:35, CSLem <[email protected]> wrote: > > > > >>> The logic I create here will certainly be used later in a web version > > >>> of this application. Keeping the session to a minimum will be > > >>> essential there. I am really trying to implement a Session per > > >>> Conversation sort of model with that web future in mind and was > hoping > > >>> to keep the session strictly in the data layer. If I use a long- > > >>> running session the UI will have to be able to open and close the > > >>> session. > > > > >>> If I open a session and begin a transaction, then disconnect (as > > >>> opposed to closing and disposing) don't all the objects stay in the > > >>> session? As I recall, I had some issues in the first attempt at this > > >>> application because there were times when I wanted what was in the DB > > >>> - not what was cached in the session - and I could not force NHIb to > > >>> do that. For example, if I get a list of objects that is strictly for > > >>> searching, then want to update a single object in the database I need > > >>> to Get the object from the database at that time (to help eliminate > > >>> StaleObjectStateExceptions) and give that to the presentation layer - > > >>> not the object that was initially retrieved in the list. > > > > >>> On Feb 11, 5:26 pm, Diego Mijelshon <[email protected]> wrote: > > >>> > Why do you try to avoid a "long running session"? > > >>> > A session does not keep a DB connection open until you begin a > > >>> transaction. > > > > >>> > Diego > > > > >>> > On Thu, Feb 11, 2010 at 19:33, CSLem <[email protected]> > wrote: > > >>> > > But the session is closed between the Get and the commit since I > am > > >>> > > trying to avoid the long running session. That is I Get the > object, > > >>> > > close the session and hand the object to the presentation layer. > At > > >>> > > some point the object is passed back to the data layer. > > > > >>> > > As a result I have a detached object and need to open a new > session > > >>> > > and attach the object to the new session that I have. Doesn't > that > > >>> > > mean I have to call some save method or lock? I have tried lock > and, > > >>> > > if the collections have been retrieved, I get a "dirty > collection" > > >>> > > error. > > > > >>> > > On Feb 11, 4:22 pm, Jason Meckley <[email protected]> > wrote: > > >>> > > > if the parent is managing the child entity and the parent is > > >>> retrieved > > >>> > > > from the database there is no reason to explicitly call any of > the > > >>> > > > Save operations. NH will do this for you. example > > > > >>> > > > var id = 1; > > >>> > > > var nameOfChild = "Jason"; > > >>> > > > using(var tx = session.BeginTransaction()) > > >>> > > > { > > >>> > > > try > > >>> > > > { > > >>> > > > var parent = session.Get<Parent>(id); > > >>> > > > parent.Add(nameOfChild); > > >>> > > > tx.Commit(); > > >>> > > > } > > >>> > > > catch > > >>> > > > { > > >>> > > > tx.Rollback(); > > >>> > > > throw; > > >>> > > > } > > > > >>> > > > } > > > > >>> > > > where parent.Add looks like > > >>> > > > class Parent > > >>> > > > { > > >>> > > > private IList<Child>() children = new List<Child>(); > > > > >>> > > > public virtual void Add(string name) > > >>> > > > { > > >>> > > > var child = new Child{Name = name, Parent = this}; > > >>> > > > children.Add(child); > > >>> > > > } > > > > >>> > > > } > > > > >>> > > > On Feb 11, 4:59 pm, CSLem <[email protected]> wrote: > > > > >>> > > > > Sorry for the long delay. I am still struggling to get the > maps > > >>> > > > > correct and SQL performing as I need. > > > > >>> > > > > I do add the child to the list. Right now, after some changes > to > > >>> > > > > cascade options and logic I have the tests doing all three > > >>> operations. > > >>> > > > > However, it only works in a long running session. > > > > >>> > > > > My simple view of the app is this: > > >>> > > > > 1) Get an object from the data layer. This starts with Parent > so > > >>> the > > >>> > > > > first object I get is the parent with no lazy collections > loaded. > > >>> > > > > 2) Close the session > > >>> > > > > 3) Let the user do whatever with the parent object > > >>> > > > > 4) IF the user needs the collection or collections, open a > new > > >>> > > > > session, retrieve the collections, close the session > > >>> > > > > 5) Let the user make necessary changes to Parent and Children > > >>> > > > > 6) When the user indicates they want to save open a new > session, > > >>> call > > >>> > > > > session.SaveOrUpdate(parent) and have the data layer cascade > > >>> whatever > > >>> > > > > is changed. > > > > >>> > > > > I would assume this is how an httpsession is handled. I am > not in > > >>> a > > >>> > > > > web session but still don't want the session to remain open > since > > >>> the > > >>> > > > > users often open the application and leave it up all day, > > >>> creating a > > >>> > > > > very long connection if I don't destroy the session after > each > > >>> action. > > > > >>> > > > > If I close the session after I get the object(s) then when I > pass > > >>> the > > >>> > > > > Parent back to the data layer and call SaveOrUpdate(parent) > > >>> NHibernate > > >>> > > > > issues an UPDATE statement for every object in the graph - > Parent > > >>> and > > >>> > > > > EVERY child that has been retrieved. I have tried used > > >>> > > > > SaveOrUpdateCopy instead but then seem to have problems in my > > >>> unit > > >>> > > > > test if I attempt to update the object twice. That is, get > the > > >>> Parent > > >>> > > > > and Children, update something on one of the Children, send > it > > >>> back to > > >>> > > > > the database. Update something on the Parent, send it back to > the > > >>> > > > > database. At this point (using SaveOrUpdateCopy) I get a "row > was > > >>> > > > > updated or deleted...." error. > > > > >>> > > > > I just can't seem to find the right combination of attributes > and > > >>> > > > > method calls to do what I assume is a pretty normal process. > > > > >>> > > > > Here is a sample test. > > > > >>> > > > > Parent parent = CurrentSession.GetById(parentId); //includes > > >>> logic to > > >>> > > > > open a session, retrieve and close > > >>> > > > > parent.Amplify(); //retrieves the child collection(s) using > a > > >>> > > > > separate session, close > > >>> > > > > parent.child.comment = "NEW TEXT"; > > >>> > > > > parent.ApplyChanges(); //opens a session, calls > > >>> > > > > session.SaveOrUpdate(parent) > > >>> > > > > parent.someproperty = "New value"; > > >>> > > > > parent.ApplyChanges(); > > > > >>> > > > > The second ApplyChanges opens the session correctly but > either > > >>> fails > > >>> > > > > with the row was updated error (using SaveOrUpdateCopy) or > issues > > >>> > > > > UPDATE statements for EVERY object in parent and child > > >>> collections. > > >>> > > > > (using SaveOrUpdate). > > > > >>> > > > > Today I switched my timestamp to a version column thinking > that > > >>> maybe > > >>> > > > > the timestamp was not performing well as a concurrency check > but > > >>> the > > >>> > > > > behavior is still exactly the same. Short of opening a > session > > >>> when I > > >>> > > > > start the application and closing it when I am done I am not > sure > > >>> > > > > where to go from here. > > > > >>> > > > > On Feb 5, 3:23 pm, Diego Mijelshon <[email protected]> > > >>> wrote: > > > > >>> > > > > > You need to add the Child to ChildList. Otherwise, how > would > > >>> > > NHibernate find > > >>> > > > > > it? > > > > >>> > > > > > Diego > > > > >>> > > > > > On Fri, Feb 5, 2010 at 13:07, CSLem < > [email protected]> > > >>> wrote: > > >>> > > > > > > I have what I think is a VERY simple mapping. This > particular > > >>> one > > >>> > > uses > > >>> > > > > > > DB generated Ids for all tables and, depending on how I > set > > >>> up > > >>> > > inverse/ > > >>> > > > > > > cascade I can get saves to work all the time but either > > >>> inserts or > > >>> > > > > > > deletes fail. Insert sometimes fails with a Cannot insert > > >>> NULL > > >>> > > value > > >>> > > > > > > in ChildId column or appears to work but issues no INSERT > to > > >>> the > > >>> > > SQL > > >>> > > > > > > database. When I get the inserts to work the deletes fail > due > > >>> to > > >>> > > the > > >>> > > > > > > foreign key relationship on the child. > > > > >>> > > > > > > I always want the Parent to manage the relationship to > the > > >>> DB. That > > >>> > > > > > > is, for this application, there is never a need to try to > > >>> insert/ > > >>> > > > > > > update/delete except through the parent so when the > update > > >>> > > statement > > >>> > > > > > > is issued it is always session.saveorupdate(Parent); I > would > > >>> expect > > >>> > > > > > > that to issue the necessary INSERT Parent..., INSERT > > >>> Child...; etc > > >>> > > > > > > with the correct ID or the necessary UPDATE/DELETE > > >>> statements. > > > > >>> > > > > > > I am using the NHibernate V2.1.0.4000 and NHibernate.Linq > > >>> > > V1.0.0.4000, > > >>> > > > > > > although I don't know that Linq matters on this side of > the > > >>> > > equation. > > > > >>> > > > > > > The current classes/maps- 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. > > -- You received this message because you are subscribed to the Google Groups "nhusers" group. 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