how to deal with "A CMR collection may only be used within t

john_woo Feb 2, 2006 7:09 AM

Hi,

Two local EJB represent 2 tables,

Department (Dep_id, name)
Employee (Emp_id, Dep_id, name)

Department has 1 to many relationship with Employee. so

DepartmentBean has a method

public abstract Collection getEmployee();

in jbosscmp-jdbc.xml, I defined:
<ejb-relation>
<ejb-relation-name>department-employee</ejb-relation-name>
<ejb-relationship-role>
<ejb-relationship-role-name>DepartmentRelationshipRole</ejb-relationship-role-name>
<key-fields>
<key-field>
<field-name>departmentId</field-name>
<column-name>DEPARTMENT_ID</column-name>
</key-field>
</key-fields>
</ejb-relationship-role>

then I'm using a servlet (in same ear as ejb.jar in), but when trying to do the following:

// lookup no problem
Collection c = d.getEmployee();

JBoss shows error:

java.lang.IllegalStateException: A CMR collection may only be used within the transction in
which it was created
at org.jboss.ejb.plugins.cmp.jdbc.bridge.RelationSet.getIdList(RelationSet.java:66)
at org.jboss.ejb.plugins.cmp.jdbc.bridge.RelationSet.access$000(RelationSet.java:32)
at org.jboss.ejb.plugins.cmp.jdbc.bridge.RelationSet$1.(RelationSet.java:359)
at org.jboss.ejb.plugins.cmp.jdbc.bridge.RelationSet.iterator(RelationSet.java:357)
at MyServlet.init(MyServlet.java:73)

...

---
Can any help?

Thanks lots in advance

John
Toronto

1. Re: how to deal with

lafr Feb 5, 2006 4:41 PM (in response to john_woo)

The message "A CMR collection may only be used within the transction in which it was created!" was often discussed here.

Creating the collection and iterating through it have to be don in the same transaction.
From a servlet you'll probably have to use a user transaction.
UserTransaction transaction = ...lookup( "UserTransaction");
transaction.begin();
Collection c = d.getEmployee();
Iterator iter = c.iterator();
while ( iter.hasNext() ) {
// do something useful
}
transaction.commit();
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