I have a category. A category can have other children category, and a parent category.
This is the mapping file:

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
<class name="model.Category" table="category">
<id name="id" column="category_id" type="long" unsaved-value="null">
<generator class="native"/>
</id>
<property name="name" type="string"/>
<property name="description" type="string"/>

<set name="children" lazy="true" cascade="save-update" inverse="true">
<key column="category_id"/>
<one-to-many class="model.Category"/>
</set>

<many-to-one name="parent" column="parent_id" class="model.Category" cascade="none"/>

</hibernate-mapping>


Now in the source code i retireve a category with
Category cat = session.get(id);

then i close the session and i try to retry the parent, and the parent of the parent.
I expected to obtain an error, instead hibernate seems to have loaded the whole tree from the current category to the root (but not the children due to the lazy attribute setted to true in the children set).

I am a begginer so i would like to ask you if there is the possibility to lazy initialize also the many-to-one association.

all this is described in the reference guide

lazy attribute of class element + outer join of many to one....

read the reference guide please

I have read it, and I setted lazy=true and outer-join=false:


<hibernate-mapping>
<class name="model.Category" table="category">
<id name="id" column="category_id" type="long" unsaved-value="null">
<generator class="native"/>
</id>
<property name="name" type="string"/>
<property name="description" type="string"/>

<set name="children" lazy="true" cascade="save-update" inverse="true">
<key column="category_id"/>
<one-to-many class="model.Category"/>
</set>

<many-to-one name="parent" column="parent_id" class="model.Category" cascade="none" outer-join="false"/>

<set name="documents" inverse="true" cascade="save-update" lazy="true">
<key column="category_id"/>
<one-to-many class="model.Document"/>
</set>
</class>
</hibernate-mapping>

And if I retrieve a categeroy that is a leaf of the tree hibernate perform N select, N = depth of the tree.
So this is not what i want.
Did i miss something?

show document.hbm.xml

<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 2.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd">

<hibernate-mapping>
<class name="model.Document" table="document">
<id name="id" column="document_id" type="long" unsaved-value="null">
<generator class="native"/>
</id>
<property name="name" type="string"/>
<property name="description" type="string"/>
<property name="text" type="text"/>
<many-to-one name="category"
class="model.Category"
column="category_id"
not-null="true"/>
</class>
</hibernate-mapping>

change
<class name="model.Document" table="document">
to
<class lazy="true" name="model.Document" table="document">

change
<many-to-one name="parent" column="parent_id" class="model.Category" cascade="none" outer-join="false"/>
to
<many-to-one name="parent" column="parent_id" class="model.Category" cascade="none" outer-join="auto"/>

add a default constructor in Document

and next time read the reference guide carefully