Hi,
I am using ojb1.0_rc4, ODMG api with OJB queries, mysql4 (innodb tables) in Linux
Red Hat 7.3 (kernel 2.4.20-20.7).
I am having a problem using non-decomposed m:n associations. Here is the
description of my problem: in my business model I have an User class and a Group
class. User and Group are m:n associated using an indirection table (please, see a
portion of my repository_user.xml file in the end of this email). So I have the
following tables: user_1, group_1 and user_group (m:n mapping table). After some
testing I found out that when I locked User before I locked Group, the database
(mysql) reported a foreign key violation error. Here's an example:
transaction.begin();
User u=new User();
//set user properties
Group g=new Group();
//set group properties
transaction.lock(u,transaction.WRITE);
transaction.lock(g,transaction.WRITE);
u.addGroup(g);
transaction.commit();
If I lock group before I lock user, there's no problem. After some more
investigation using p6spy I found out that changing the locking order also changed the
order of the insert statements executed in the database, hence the foreign key error.
OJB is inserting a record in user_group (m:n mapping table) before it has inserted the
user and group records.
By the way, the user class also has 3 subclasses (teacher, student and
coordinator). Do you think that using inheritance has anything to do with this problem?
How can I fix this problem? Is it a bug?
Thanks,
Jair Jr
Here's a portion of my repository_user.xml file:
<!-- Definitions for com.jma.interescola.core.User -->
<class-descriptor class="com.jma.interescola.core.User" table="user_1">
<field-descriptor id="1" name="_id" column="id" jdbc-type="INTEGER" primarykey="true"
autoincrement="true"/>
<field-descriptor id="2" name="_name" column="name" jdbc-type="VARCHAR"/>
<field-descriptor id="3" name="_email" column="email" jdbc-type="VARCHAR"/>
<field-descriptor id="4" name="_phone" column="phone" jdbc-type="VARCHAR"/>
<field-descriptor id="5" name="_password" column="password" jdbc-type="VARCHAR"/>
<collection-descriptor name="_participations"
element-class-ref="com.jma.interescola.core.Participation" orderby="_exam._start"
sort="ASC">
<inverse-foreignkey field-id-ref="2"/>
</collection-descriptor>
<collection-descriptor name="_groups"
element-class-ref="com.jma.interescola.core.Group" indirection-table="user_group"
orderby="_id" sort="ASC">
<fk-pointing-to-this-class column="userId"/>
<fk-pointing-to-element-class column="groupId"/>
</collection-descriptor>
</class-descriptor>
<!-- Definitions for com.jma.interescola.core.Student -->
<class-descriptor class="com.jma.interescola.core.Student" table="student">
<field-descriptor id="1" name="_id" column="id" jdbc-type="INTEGER" primarykey="true"
autoincrement="true"/>
<reference-descriptor auto-delete="true" name="super"
class-ref="com.jma.interescola.core.User">
<foreignkey field-ref="_id"/>
</reference-descriptor>
<!--<collection-descriptor name="_participations"
element-class-ref="com.jma.interescola.core.Participation" orderby="_exam._start"
sort="ASC">
<inverse-foreignkey field-id-ref="2"/>
</collection-descriptor>-->
</class-descriptor>
<!-- Definitions for com.jma.interescola.core.Teacher -->
<class-descriptor class="com.jma.interescola.core.Teacher" table="teacher">
<field-descriptor id="1" name="_id" column="id" jdbc-type="INTEGER" primarykey="true"
autoincrement="true"/>
<reference-descriptor auto-delete="true" name="super"
class-ref="com.jma.interescola.core.User">
<foreignkey field-ref="_id"/>
</reference-descriptor>
</class-descriptor>
<class-descriptor class="com.jma.interescola.core.Coordinator" table="coordinator">
<field-descriptor id="1" name="_id" column="id" jdbc-type="INTEGER" primarykey="true"
autoincrement="true"/>
<reference-descriptor auto-delete="true" name="super"
class-ref="com.jma.interescola.core.User">
<foreignkey field-ref="_id"/>
</reference-descriptor>
</class-descriptor>
<!-- Definitions for com.jma.interescola.core.Group -->
<class-descriptor class="com.jma.interescola.core.Group" table="group_1">
<field-descriptor id="1" name="_id" column="id" jdbc-type="INTEGER" primarykey="true"
autoincrement="true"/>
<field-descriptor id="2" name="_schoolId" column="schoolId" jdbc-type="INTEGER"/>
<field-descriptor id="3" name="_name" column="name" jdbc-type="VARCHAR"/>
<field-descriptor id="4" name="_year" column="year" jdbc-type="INTEGER"/>
<reference-descriptor name="_school" class-ref="com.jma.interescola.core.School">
<foreignkey field-id-ref="2"/>
</reference-descriptor>
</class-descriptor>
