I'm using hbm2ddl to generate my schema from a mapping file. If I leave off the "property-ref" attribute, it generates a foreign key constraint as expected. If I add the "property-ref" attribute, it does not. Is there a trick here? I could always manually add it after the generate but I'd like to understand why it isn't doing it. Thanks in advance.


<?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 package="eg">

<class name="User" table="users">
<id name="id" column="id" type="long">
<generator class="native"/>
</id>
<property name="username" column="username" type="string" length="12"
not-null="true" unique="true" />
<property name="password" type="string" length="8" not-null="true" />
<property name="firstname" type="string" length="15" />
<property name="lastname" type="string" length="25" />
<property name="phone" type="string" length="20" />
<property name="email" type="string" length="40" />
</class>

<class name="Role" table="roles">
<id name="id" column="id" type="long">
<generator class="native"/>
</id>
<property name="role" type="string" length="20"
not-null="true" unique="true"/>
<many-to-one name="username" property-ref="username"
class="eg.User" not-null="true" />
</class>

</hibernate-mapping>

[/code]

Not specifying a property-ref creates a foreign key, coz by default the primary key of the referenced table is used - User.id. If you provide a property reference, like "User.username" in your case, you are referencing another column (note this is not the relationship you want in the first place, right??) And User.username is not a key anyways, so you wont have a foreign constraint either. Best that hibernate can do is, ignore it rather than fail with an exception by not even creating a basic table schema.

If you want a relationship on username, you could consider adding that as the id?? or add an index over it with the index attribute or a unique constraint..cant say if that would work, never tried it.

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