EJB - Simple CMR one-to-one unidirectional relationship

[Patrick Maddox]

At work I was handed a copy of Enterprise JavaBeans 3rd Ed. and told to
convert an app written entirely of regular JavaBeans and JDBC calls into
EJB. I haven't had too much trouble, but I've had some problems with
relationships. This one should be really simple, but I haven't been
able to set it up correctly. The two beans in this relationship
represent an Account and a CreditCard. Each bean has a primary key
named accid, and they should be equivalent. The accid in Account is
generated by the database, by auto_increment. The CreditCard accid
should come from the Account. As I understand it, when the AccountLocal
is created, a corresponding CreditCardLocal should be as well. I get
various problems when I try different stuff, so I'll just post the
relevant code, and hopefully somebody can tell me what's goin on. I'm
using JBoss as the J2EE server.

************** ejb-jar.xml ****************

<ejb-jar>
<enterprise-beans>
<entity>
<ejb-name>CreditCardEJB</ejb-name>
<local-home>com.blazingmedia.xplode.account.ejb.
CreditCardHomeLocal</local-home>
<local>com.blazingmedia.xplode.account.ejb.
CreditCardLocal</local>
<ejb-class>com.blazingmedia.xplode.account.ejb.
CreditCardBean</ejb-class>
<persistence-type>Container</persistence-type>
<prim-key-class>java.lang.Integer</prim-key-
class>
<reentrant>False</reentrant>
<abstract-schema-name>CreditCard</abstract-
schema-name>
<cmp-field><field-name>accid</field-name></cmp-
field>
<cmp-field><field-name>ccCVVS</field-name></cmp-
field>
<cmp-field><field-name>ccExpire</field-name></
cmp-field>
<cmp-field><field-name>ccName</field-name></cmp-
field>
<cmp-field><field-name>ccNumber</field-name></
cmp-field>
<cmp-field><field-name>ccType</field-name></cmp-
field>
<primkey-field>accid</primkey-field>
<security-identity><use-caller-identity/></
security-identity>
</entity>

<entity>
<ejb-name>AccountEJB</ejb-name>
<local-home>com.blazingmedia.xplode.account.ejb.
AccountHomeLocal</local-home>
<local>com.blazingmedia.xplode.account.ejb.
AccountLocal</local>
<ejb-class>com.blazingmedia.xplode.account.ejb.
AccountBean</ejb-class>
<persistence-type>Container</persistence-type>
<prim-key-class>java.lang.Integer</prim-key-
class>
<reentrant>False</reentrant>
<abstract-schema-name>Account</abstract-schema-
name>
<cmp-field><field-name>accid</field-name></cmp-
field>
<cmp-field><field-name>username</field-name></
cmp-field>
<cmp-field><field-name>firstName</field-name></
cmp-field>
<cmp-field><field-name>lastName</field-name></
cmp-field>
<cmp-field><field-name>street1</field-name></cmp-
field>
<cmp-field><field-name>street2</field-name></cmp-
field>
<cmp-field><field-name>city</field-name></cmp-
field>
<cmp-field><field-name>state</field-name></cmp-
field>
<cmp-field><field-name>zip</field-name></cmp-
field>
<cmp-field><field-name>country</field-name></cmp-
field>
<cmp-field><field-name>phone</field-name></cmp-
field>
<cmp-field><field-name>billType</field-name></
cmp-field>
<cmp-field><field-name>planType</field-name></
cmp-field>
<cmp-field><field-name>date</field-name></cmp-
field>
<cmp-field><field-name>fax</field-name></cmp-
field>
<cmp-field><field-name>company</field-name></cmp-
field>
<cmp-field><field-name>referredBy</field-name></
cmp-field>
<cmp-field><field-name>active</field-name></cmp-
field>
<cmr-field><cmr-field-name>creditCard</cmr-field-
name></cmr-field>
<primkey-field>accid</primkey-field>
<security-identity><use-caller-identity/></
security-identity>
</entity>

<relationships>
<ejb-relation>
<ejb-relation-name>Account-CreditCard</ejb-
relation-name>
<ejb-relationship-role>
<ejb-relationship-role-name>
Account-has-a-CreditCard
</ejb-relationship-role-name>
<multiplicity>One</multiplicity>
<relationship-role-source>
<ejb-name>AccountEJB</ejb-name>
</relationship-role-source>
<cmr-field>
<cmr-field-name>creditCard</cmr-
field-name>
</cmr-field>
</ejb-relationship-role>
<ejb-relationship-role>
<ejb-relationship-role-name>
CreditCard-belongs-to-Account
</ejb-relationship-role-name>
<multiplicity>One</multiplicity>
<cascade-delete/>
<relationship-role-source>
<ejb-name>CreditCardEJB</ejb-
name>
</relationship-role-source>
</ejb-relationship-role>
</ejb-relation>
</relationships>
</ejb-jar>

*************** ejb-jar.xml ****************

*************** jbosscmp-jdbc.xml ****************

<jbosscmp-jdbc>
<enterprise-beans>
<entity>
<ejb-name>CreditCardEJB</ejb-name>
<table-name>CreditCards</table-name>
<cmp-field><field-name>accid</field-name></cmp-field>
<cmp-field><field-name>ccCVVS</field-name></cmp-
field>
<cmp-field><field-name>ccExpire</field-name></
cmp-field>
<cmp-field><field-name>ccName</field-name></cmp-
field>
<cmp-field><field-name>ccNumber</field-name></
cmp-field>
<cmp-field><field-name>ccType</field-name></cmp-
field>
<entity-command name="mysql-get-generated-keys"/</entity>

<entity>
<ejb-name>AccountEJB</ejb-name>
<table-name>Accounts</table-name>
<cmp-field><field-name>accid</field-name><auto-
increment/></cmp-field>
<cmp-field><field-name>username</field-name></
cmp-field>
<cmp-field><field-name>firstName</field-name></
cmp-field>
<cmp-field><field-name>lastName</field-name></
cmp-field>
<cmp-field><field-name>street1</field-name></cmp-
field>
<cmp-field><field-name>street2</field-name></cmp-
field>
<cmp-field><field-name>city</field-name></cmp-
field>
<cmp-field><field-name>state</field-name></cmp-
field>
<cmp-field><field-name>zip</field-name></cmp-
field>
<cmp-field><field-name>country</field-name></cmp-
field>
<cmp-field><field-name>phone</field-name></cmp-
field>
<cmp-field><field-name>billType</field-name></
cmp-field>
<cmp-field><field-name>planType</field-name></
cmp-field>
<cmp-field><field-name>date</field-name></cmp-
field>
<cmp-field><field-name>fax</field-name></cmp-
field>
<cmp-field><field-name>company</field-name></cmp-
field>
<cmp-field><field-name>referredBy</field-name></
cmp-field>
<cmp-field><field-name>active</field-name></cmp-
field>
<entity-command name="mysql-get-generated-keys"/</entity>

</enterprise-beans>

<relationships>
<ejb-relation>
<ejb-relation-name>Account-CreditCard</ejb-
relation-name>
<foreign-key-mapping/>
<ejb-relationship-role>
<ejb-relationship-role-name>Account-has-
a-CreditCard</ejb-relationship-role-name>
<key-fields>
<key-field>
<field-name>accid</field-
name>
<column-name>accid</
column-name>
</key-field>
</key-fields>
</ejb-relationship-role>
<ejb-relationship-role>
<ejb-relationship-role-name>CreditCard-
belongs-to-Account</ejb-relationship-role-name>
<key-fields/>
</ejb-relationship-role>
</ejb-relation>
</relationships>
</jbosscmp-jdbc>

**************** jbosscmp-jdbc.xml ***************

**************** CreditCardBean.java ***************

public abstract class CreditCardBean implements EntityBean
{
public Integer ejbCreate() throws CreateException
{
return null;
} }

public void ejbPostCreate()
{
} }

public abstract Integer getAccid();

public abstract String getCcCVVS();

public abstract String getCcExpire();

public abstract String getCcName();

public abstract String getCcNumber();

public abstract String getCcType();

public abstract void setAccid(Integer i);

public abstract void setCcCVVS(String string);

public abstract void setCcExpire(String string);

public abstract void setCcName(String string);

public abstract void setCcNumber(String string);

public abstract void setCcType(String string);

public void setEntityContext(EntityContext context) { }
public void unsetEntityContext() { }
public void ejbLoad() { }
public void ejbStore() { }
public void ejbActivate() { }
public void ejbPassivate() { }
public void ejbRemove() { }
}

****************** CreditCardBean.java ****************

**************** CreditCardLocal.java ****************

public interface CreditCardLocal extends EJBLocalObject
{
public Integer getAccid() throws EJBException;
public String getCcCVVS() throws EJBException;
public void setCcCVVS(String ccCVVS) throws EJBException;
public String getCcExpire() throws EJBException;
public void setCcExpire(String ccExpire) throws EJBException;
public String getCcName() throws EJBException;
public void setCcName(String ccName) throws EJBException;
public String getCcNumber() throws EJBException;
public void setCcNumber(String ccNumber) throws EJBException;
public String getCcType() throws EJBException;
public void setCcType(String ccType) throws EJBException;
}

****************** CreditCardLocal.java ****************

*************** CreditCardHomeLocal.java ****************

public interface CreditCardHomeLocal extends EJBLocalHome
{
public CreditCardLocal create()
throws CreateException, EJBException;

public CreditCardLocal findByPrimaryKey(Integer pk)
throws FinderException, EJBException;
}

****************** CreditCardHomeLocal.java **************