You can use Session.Save(..) for the newly created objects. This way you force NHibernate to do an INSERT. The problem is that sometimes this fails because a root/parent objects does not yet exists in either the database or set to the objects properties. In that case you should
* take the lookup for granted as NHibernate does not know if it needs to insert or update. * don't use assigned identifiers * remove the explicit relation between the child and the parent and don't use treat it like an aggregate Regarding the 2nd, don't use assigned identifiers, I learned the hard way that assigned identifiers should not be used as primary keys within the database to share as it prevents optimized saving of aggregates in nhibernate. This conflicts with modern principles that you want to generate a key upfront to correlate different actions to. When you need such keys then you should keep the primary key internal/protected so that it does not have assigned identifiers but use for example hilo and have a guid property as a 'natural' key.What I dislike about this is that you will always need to join between the parent/child to fetch the child records. If that key was part of the primary key then you could just do a simple select. Problem is that in most situations you would want to say to nhibernate 'treat proxies as updates and non proxies as inserts'. That would prevent such lookups. Hope this helps! On Tue, Mar 20, 2012 at 12:34 PM, Richard Brown <[email protected]>wrote: > If you use assigned-identifier, and mix 'old'+'new' (i.e., > persistent+transient) objects, NH cannot determine what has to be inserted > and what is already there just by looking at the IDs. > > You should load the existing persisted entities first. > > var referenceEntity = > session.Load<ReferenceType>(idThatIKnowExistsInTheDb); > > The best solution is to not use assigned identifiers. > > > On 19 March 2012 21:26, guilemsola <[email protected]> wrote: > >> Hi all, >> >> I have discovered that with nhibernate profiler with entities created >> for the very first time... >> >> In my application I create a new entity that has a list of steps, and >> each step a list of values. (I'm using inverses on mappings). Also >> entities and steps references to master values already in db. So there >> is a kind of mix of old and new objects. >> >> When I do the first Save I do Session.Save(entity) and the whole tree >> is saved in database as it should be, but NH profiler warns about >> that: >> >> Unable to determine if StepValueEntity with assigned identifier >> ede6a5ee-b4bd-4f67-9c64-11ef85b7d6ff is transient or detached; >> querying the database. Use explicit Save() or Update() in session to >> prevent this. >> >> And effectively prior all the new entities insert there are a lot of >> useless selects from NH because entities are not on DB. >> >> This is very inefficient, so what is the correct way to store those >> new entities and tell NH that they are new? >> >> >> >> FYI this is how I do mapping for identity columns, maybe this doesn't >> give a clue to nhibernate to know about what are new and already >> persisted entities and I should do it in another way. >> >> Id(x => >> x.Id).Column("GUID_PIPELINE_STEP_PARAMETER").GeneratedBy.Assigned(); >> >> Thanks 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]. >> 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. > 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. > -- Ramon -- 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.
