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| <title>Adding relationship roles to keys</title> |
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| <h1 class="topictitle1">Adding relationship roles to keys</h1> |
| <div><p>You can add a relationship role to a key class.</p><div class="skipspace"><p>The relationship role to be added must have the following characteristics:</p> |
| <ul><li>It is not many-valued.</li> |
| <li>It is both required and navigable.</li> |
| <li>It holds a foreign key.</li> |
| </ul> |
| <p>Additionally, the enterprise bean to which the key will be added must |
| be a root bean (does not inherit from a supertype). This is because inherited |
| beans must use the primary key class of the supertype and therefore the key |
| class shape cannot be modified.</p> |
| <p>The following task refers to two enterprise |
| beans: one that contains a role (<i>this</i> bean) and one represented in |
| the role (the <i>other</i> bean).</p> |
| </div> |
| <ol><li><span>In the Project Explorer view of the J2EE perspective, right-click |
| the Deployment Descriptor for your EJB project and select <span class="menucascade"><span class="uicontrol">Open |
| With</span> > <span class="uicontrol">Deployment Descriptor Editor</span></span> to |
| open the deployment descriptor editor.</span></li> |
| <li><span>On the <span class="uicontrol">Bean</span> page, select the enterprise |
| bean that contains the relationship role that you want to add to the key, |
| and scroll to the Relationships section.</span></li> |
| <li><span>Click <span class="uicontrol">Add to Key</span>.</span></li> |
| </ol> |
| <div class="skipspace"> <p>This action adds the key fields of the other bean to both the |
| key class and the bean class of this bean. When a role is added to the primary |
| key, the association is also regenerated.</p> |
| <p>Be careful when removing beans |
| from an association. If you have added one of the roles to the key of one |
| of the beans, the bean with the role in the key must be removed before the |
| other bean. A database constraint may enforce this (even if the role is not |
| part of the key). However, if there is no database constraint, problems could |
| still occur. For example, suppose that you have Customer and Address beans |
| in a 1:1 association where the customer role of the Address bean holds the |
| foreign key and the customer role is the primary key of the Address bean. |
| If you were to remove the Customer bean without first removing the Address |
| bean, the association maintenance code, while trying to set the Address bean's |
| customer role foreign-key to null, will also be trying to set the primary |
| key of the Address bean to null.</p> |
| </div> |
| </div> |
| |
| <div><p><b class="reltaskshd">Related tasks</b><br /> |
| <a href="../topics/teaddsecurityidbean.html" title="Assigning a security identity to a bean is useful when another bean calls that bean. The security identity can be set to use the identity of the caller or the identity of a specific security role.">Adding a security identity (bean level)</a><br /> |
| <a href="../topics/teaddsecurityrole.html" title="You need to add security roles in order to build method permissions.">Defining security roles for EJB modules</a><br /> |
| <a href="../../com.ibm.etools.j2eeapp.doc/topics/tjaddrefsecurityrole.html">Adding security role references</a><br /> |
| </p> |
| </div> <br /> |
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