Hi, at first my example mapping:
<class name="Blog">
<id name="Id">
<generator class="guid.comb" />
</id>
<set name="Posts" cascade="all">
<key column="Blog_Id" not-null="true" />
<one-to-many class="Post" />
</set>
</class>
<class name="Post">
<id name="Id">
<generator class="guid.comb" />
</id>
</class>
Ive choose to use an Uni-Directional association, because the model is
cleaner and i don't have to manage the other direction.
So my problem is that i want to allow this
blog.Posts.Add(new Post());
but when i do
session.Save(new Post());
NHibernate should throw an exception since the Post have no Blog
assigned to it.
Since database not-null constrains dose not work as described in
documentation:
Very Important Note: If the <key> column of a <one-to-many>
association is declared NOT NULL, NHibernate may cause constraint
violations when it creates or updates the association. To prevent this
Problem, you must use a bidirectional association with the many valued
end (the set or bag) marked as inverse="true". See the discussion of
bidirectional associations later in this chapter.
Because it dose the insert first with the Blog_Id null
and after that it it updates the Database with the Blog_Id.
So my question is, is there any generic way to prevent NHibernate from
inserting Posts without an associated Blog? I think about creating an
event, but i am not sure which is the best strategy to detect this an a
generic way.
And second, since the database way is not supported, isnt it a good idea
to add something like a soft constraint where nhibernate checks if it
has an association and throw before the transaction is committed.
Regards,
Steve
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