Hello Hudson, thanks for a very quick and good reply.
Your explanation is great! I should be able to create the conventions with this new "knowlegde" :) Martin On 5 Feb., 21:27, Hudson Akridge <hudson.akri...@gmail.com> wrote: > > Basically it means that the other side of the join is the parent/owner of > > the other object/s > > Not exactly (Read: no). The other side contains the information necessary to > save the association. In a Parent/Child relationship context, that means the > other side contains the reference back to the parent. In a RDBMS context, > that means the child contains the FK field. If you think about it in more > RDBMS terms, and not OO terms, it makes more sense. > > Here's my take on it: > The Child object, needs to be written to the child table. The child table > contains a Foreign Key that references the Parent table right? So your > Children table would contain a ParentID column. That's what the Parents > table joins to in a simple relationship. > > NHibernate can remove the terminology/use cases of RDBMS's, but only so far. > In this case, Inverse is signifying that the Parent, does not actually > contain a datapoint which will store a reference to children. That's > contained by children. Therefore the child needs to save. > > In a ManyToMany situation, they're both technically "parents", that's why > you need a join table between them. So one of them needs to be marked > inverse. it doesn't matter which one (well, it technically does, but not in > the 99% use case), just as long as only one of them is responsible for the > saving. If both of their inverses are set to false, then they're both going > to be contending for which side of the relationship is saving first, and > you're going to end up with row contention. > > Inverse should be set on OneToMany's when the Child has a reference back to > the parent (bi-directional). If the child does not have a reference back to > the parent, then inverse should be false, signifying that the Parent now > needs to manage the foreign key association with the child. > > > > > > On Fri, Feb 5, 2010 at 2:02 PM, Martin From <f...@pc.dk> wrote: > > Hello, > > > i am trying to understand how Inverse() should be used and how it can > > somehow work in a Convention for the different join types in fluent > > nhibernate. > > > Does anyone have an example of a typical implementation of how to use > > Inverse ? Or is there no typical pattern of how it should be used ? > > > I am having some difficulties figuring out how it should be used. > > As I understand it, Inverse() assigns the resposibility of saving the > > object to the other end of the join, which is also mentioned on the > > Fluent Nhibernate Wiki. Basically it means that the other side of the > > join is the parent/owner of the other object/s ? > > > As far as i have been able to find out Inverse is always set to > > "false" on both sides per default in Hibernate, and it is not possible > > to set Inverse on the Reference mapping. Is defaults different in > > Fluent Nhibernate ? > > I guess in most cases the side with the HasMany or HasManyToMany join > > declaration is the one responsible for the other objects so Inverse > > should be set on the Reference which is not possible (- clearly i dont > > understand it correctly). > > > When looking at the example from "Getting Started" on the Fluent > > Nhibernate page i get confused because Inverse() is set on the HasMany > > join declared for the Property "Staff" in the Store mappings. > > But looking at the database diagram the Employee (Staff) table have a > > relation to the Store table through the foreign key Store_id, which > > means that a Store needs to exist in order for the Employee to exist, > > therefore in my mind the Store object should have the responsibility > > of saving an Employee object. > > > Fluent Nhibernate - Getting Started - > >http://wiki.fluentnhibernate.org/Getting_started#Mappings > > > I clearly must be misunderstanding something about Inverse. > > Maybe it is the opposite of what i think? - That Inverse() should be > > set on the side that is responsible of saving the objects in the other > > end of the join ? > > > Or maybe it means something else ? :) > > > Martin > > > ps. i guess how Inverse() works is more a Hibernate related question, > > but what i am trying to do is create a Fluent Nhibernate Convetion > > using it "correctly". > > > -- > > You received this message because you are subscribed to the Google Groups > > "Fluent NHibernate" group. > > To post to this group, send email to fluent-nhibern...@googlegroups.com. > > To unsubscribe from this group, send email to > > fluent-nhibernate+unsubscr...@googlegroups.com<fluent-nhibernate%2bunsubscr...@googlegroups.com> > > . > > For more options, visit this group at > >http://groups.google.com/group/fluent-nhibernate?hl=en. > > -- > - Hudsonhttp://www.bestguesstheory.comhttp://twitter.com/HudsonAkridge- Skjul > tekst i anførselstegn - > > - Vis tekst i anførselstegn - -- You received this message because you are subscribed to the Google Groups "Fluent NHibernate" group. 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