hello everyone!

i need a little architectural advice concerning lazy loading.
(see mapping files at the bottom).

my class "asset" is used to basically hold a blob of an image.
the other class "record" has a list of "assets".

now, i don't want to populate the blobs in "asset" when an instance is
loaded from the db (obviously because it's slow and takes up much mem).

my problem: if i set the list or the blob-properties to be lazy,
i get an exception because the session is already closed when i later
try to access them.
that's because i'm running hibernate from spring.

now what can i do?
is there another way of making them lazy?
do i have to manually load the blobs when i need them
and remove all logical connections in the classes?
can i make hibernate instantiate the "assets" excluding the blobs?
(kind of "projection at creation time")

thank you very much for your help!
felix

Hibernate version:
3.0.5

Mapping documents:

*** note: some properties are omitted for the sake of clarity ***

<hibernate-mapping default-lazy="false">
<class name="Record" table="record">
<id name="id" column="RECORD_ID">
<generator class="native"/>
</id>

<list name="assets" cascade="all-delete-orphan" lazy="false">
<key column="RECORD_ID"/>
<list-index column="asset_order"/>
<one-to-many class="Asset"/>
</list>
</class>
</hibernate-mapping>

---

<hibernate-mapping default-lazy="false">
<class name="Asset" table="asset">
<id name="id" column="ASSET_ID">
<generator class="native"/>
</id>

<property name="thumbnailBlob" lazy="true" column="thumbnail_blob" type="java.sql.Blob" length="65538"/>
<property name="previewBlob" lazy="true" column="preview_blob" type="java.sql.Blob" length="65538"/>
<property name="fullBlob" lazy="true" column="full_blob" type="java.sql.Blob" length="268435456"/> <!-- 256 MB -->
</class>
</hibernate-mapping>

Can you give any details about how you are accessing "record" and the set of "asset"?

Probably (I'm guessing now :) you are using a DAO which extends HibernateDaoSupport to get the "record" and outside the DAO you are trying to access the set of "asset". BUT... the session is opened when you call the DAO and closed when you exit. If you want to keep the session opened you should use a OpenSessionInView filter or HibernateInterceptor. Using these, the session is opened when you call the service layer and closed when you exit to presentation layer.

I hope this helps,

José Luis.