Re: questions about sql logging and the Inverse in a one to many relationship

[Andrewz]

Anyone? I am a bit surprised by the lack of feedback

On Thursday, December 20, 2012 2:13:28 AM UTC+2, Andrewz wrote:

Hello,

I have a bi-directional one to many relationship between a User and a Group, defined as follows:

http://pastebin.com/qxYZc4jV

Note that the Inverse is not set. Based on my understanding this means that NHibernate sets the Group_Id each of for the User automatically

Here is my program, adding a new group and assigning an existing user to this group:

var user = session.Get<User>(1);              

var group = new Group();

group.Users.Add(user);

user.Group = group;

session.Save(user);

Question #1: The SQL output I get in the console using the show_sql setting, is this one: http://pastebin.com/Qiagzt6J

                    It does not show how the Group_id is set for the user, only the group insert.

                    Why is that? Isn't SQL output showing everything? How to see the complete SQL?

Question #2: Next, I am adding a new user to an existing group

 var group = session.Load<Group>(1);

var user = new User();

user.Group = group;

group.Users.Add(user);

The output is this one: http://pastebin.com/5RF7Lzq2

Why is it getting all users of the group in the 2nd statement? 

I guess it's because of accessing the collection when calling group.Users.Add(user), but why can't NHibernate see it's actually adding a new user?

The weird thing is that if I am setting Inverse() on the collection, it makes the insert without retrieving the collection, which is how it should work.

I know that in practice, setting Inverse is almost always needed(you want to have non null restriction on the Group_id not null, and without Inverse, this is not possible because the insert will fail), but I am really trying to understand what is going on.

Thanks!

Andrew

 

[Jos van der Til]

I'm guessing this has to do with using session.Load<>() as opposed to session.Get<>() which you should be using in this situation (if you weren't doing group.Users.Add() then Load would have been fine).

This might clarify some things: http://ayende.com/blog/3988/nhibernate-the-difference-between-get-load-and-querying-by-id

P.S. This is not an question about FluentNHibernate but about NHibernate, try posting this in the nhusers group.