- Interdependency between the associated classes. Coupling is bad. - Complexity of maintaining the references when associating/disassociating. This can largely be handled by the AddXXX, RemoveXXX and proper encapsulation of the collection but still it is unnecessary complexity.
On Mon, Jan 12, 2009 at 1:59 PM, Mark Jensen <[email protected]> wrote: > > interesting :) > > I understand the fact that bidirectional are rarely used, but why > would you consider it to be a design flaw? > > On Jan 12, 2:51 pm, "Ben Lovell" <[email protected]> wrote: > > It would be /slightly/ better performance wise but you should avoid > > bidirectional associations where possible. Bidirectional association is > > rarely necessary and usually highlights a flaw in your modelling. The > > performance hit isn't exactly huge anyway and unless you've measured > you're > > making a pretty big assumption. > > > > On Mon, Jan 12, 2009 at 1:47 PM, Mark Jensen <[email protected]> wrote: > > > > > woops.. i mean... im NOT sure how NH works... > > > > > On Jan 12, 2:34 pm, "Markus Zywitza" <[email protected]> wrote: > > > > Remove the not null-constraint from the database column. > > > > > > This is needed as NH works this way: > > > > 1) You save the parent > > > > 2) Parent cascades to newly created child > > > > 3) Child is saved with null FK > > > > 4) Parent updates child's FK > > > > > > On a bidirectional association, you can instead map the collection > > > > with Inverse=true and use the [BelongsTo]ed property to manage > > > > one-to-many relationships. > > > > > > However, I prefer giving up the not null constraint on foreign keys > > > > because unidirectional relations are generally less error-prone. > > > > > > -Markus > > > > > > 2009/1/12 Mark Jensen <[email protected]>: > > > > > > > Yep :) but if i remove the property from the object I get the above > > > > > error > > > > > > > On Jan 12, 2:04 pm, Colin Ramsay <[email protected]> wrote: > > > > >> You need the column in the DB but you don't need the property on > the > > > > >> post object. > > > > > > >> On Mon, Jan 12, 2009 at 12:44 PM, Mark Jensen <[email protected]> > > > wrote: > > > > > > >> > Because if I remove the property(and ofcouce the belongsto > relation) > > > I > > > > >> > get an error .. > > > > > > >> > System.Data.SqlClient.SqlException: Cannot insert the value NULL > > > into > > > > >> > column 'BlogId'.... > > > > > > >> > And as fare as I Know about databases and Nhibernate, I need the > > > > >> > blogId as my foreignkey. I dont see how nhibernate else would > know > > > how > > > > >> > to make the relation between Blog and Post if i remove BlogId > from > > > > >> > Post. > > > > > > >> > :/ > > > > > > >> > On Jan 12, 11:34 am, "Markus Zywitza" <[email protected] > > > > > > >> > wrote: > > > > >> >> Then why do have the BlogId property in there? Simply discard > it. > > > > > > >> >> -Markus > > > > > > >> >> 2009/1/12 Mark Jensen <[email protected]>: > > > > > > >> >> > haven't tested it yet, but is it really required to make it > > > > >> >> > bidirectional for this to work ? > > > > > > >> >> > because I only need it to go one way :/ > > > > > > >> >> > On Jan 10, 2:41 pm, "Markus Zywitza" < > [email protected]> > > > wrote: > > > > >> >> >> > public class Post : BaseEntity<Post> > > > > >> >> >> > { > > > > >> >> >> > [Property("BlogId", NotNull = true)] > > > > >> >> >> > public Guid BlogId > > > > >> >> >> > { > > > > >> >> >> > get { return blogId; } > > > > >> >> >> > set { blogId = value; } > > > > >> >> >> > } > > > > > > >> >> >> [BelongsTo("BlogId")] > > > > >> >> >> public Blog Blog {get; set;} > > > > > > >> >> >> > } > > > > >> >> >> >> > anyway...it is not the ID on Post that is the problem.. > it > > > is the > > > > >> >> >> >> > BlogID on Post that is empty after I persist Blog with > > > Blog.Save(). > > > > > > >> >> >> Of course, it is changed in the DB but not in the object. > Call > > > > >> >> >> post.Refresh() to reload it. If you implement it as I have > > > written > > > > >> >> >> above, you could also set Blog on the post instance instead. > > > > > > >> >> >> public void AddPost(Post post) > > > > >> >> >> { > > > > >> >> >> posts.Add(post); > > > > >> >> >> post.Blog=this; > > > > >> >> >> } > > > > > > >> >> >> -Markus > > > --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "Castle Project Users" 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/castle-project-users?hl=en -~----------~----~----~----~------~----~------~--~---
