Hello,

I am facing a weird problem with Hibernate.3.2.2.ga
when my mapping file is using a many-to-one relation =>

<hibernate-mapping>
<class name="Currencies" table="Currencies">
<id column="Currencies_Id" name="currenciesId">
<generator class="native"/>
</id>
<many-to-one class="Cities" column="Cities_Id" name="citiesRef"/>
</class>
</hibernate-mapping>

with the previous mapping , I am having lazy loading, only one select to get the Currencies
when I am adding not-found="ignore" to the mapping file

<many-to-one class="com.reuters.webaccess.vo.gen.Cities" column="Cities_Id" name="citiesRef" not-found="ignore"/>

no more lazy loading with the previous mapping file, 2 selects:
one for the Currencies, one for the Cities.

What is the link between lazy loading and the not-found attribute ?

Thank you for your help!!

A quick bump, because I'd love to see an answer on this from anyone in the know. We're experiencing the same issue.

When not-found="ignore" is specified, a missing row is treated as a null association. Since many-to-one uses a proxy to load, lazy loading will create issues if the row is not found, since an unassociated proxy will have got created. Eager fetch is therefore the solution.

Having said that, what is the issue that you are facing? We can then suggest a solution which might help you.

One of our primary business entities may optionally have a many-to-one association to a "folder" in a virtual/database-based file manager. This many-to-one association's lazy loading works perfectly well when not-found="ignore" is not specified.

However, when it is specified, Hibernate fetches the folder entity for the reason you explained previously. For some reason, fetching the folder entity causes a good chunk of the subordinate graph to be loaded. If the folder entity is fetched by ID directly, the subordinate graph is not loaded. If not-found="ignore" is not specified, none of the graph is loaded.

I've been using Hibernate for two years now, and I feel confident the mapping files are correct as they work perfectly in all other instances. As you can imagine, a virtual file system can have infinite layers in much the same way as an NTFS or FAT file system. Hence, lazy the lazy initialization ability of Hibernate is a great asset here.

Could you elaborate more on how fetch="eager" could assist in this scenario, or point me to an online document? It might be the workaround I'm looking for, as I'd like to keep the not-found exceptions suppressed while maintaining my lazy initialization strategy.

Thanks!

- James Chrystal

Try lazy="no-proxy" in the many to one definition along with not-found="ignore".

Will do - I'll post back my findings tomorrow when I test it (Friday if we get snowed in!).

Thanks again!

Just to register: i did and it was ok.



Don´t forget the instrumentation.