criteria search on a collection of mapped enums

SnapShot · **Joined:** Sat May 13, 2006 12:00 pm **Posts:** 19

Hibernate version: 3.1.2

This has probably been done a 100 times before, but as of yet I havn't found a solution.

I have a entity User that has a set of zero or more enums (UserRole) assigned to it. The mapping document was easy to create and uses a UserType similar to the class described here.

I want to do a Criteria query to return the set of User(s) that have one of a given UserRole assigned.

The mapping document is straight-forward (trimmed for simplicity).

Mapping documents:

Code:

<hibernate-mapping>

  <class name="com.test.data.User" table="users">
  
    <id name="id" column="id">
      <generator class="native"/>
    </id>
    
    <natural-id mutable="false">
      <property name="login" type="string" column="login" />
    </natural-id>
    
    <property name="email" type="string" column="email" />
    
    <component name="name" class="com.test.data.component.Name">
      <property name="prefix" type="string" column="prefix"/>
      <property name="firstName" type="string" column="first_name"/>
      <property name="lastName" type="string" column="last_name"/>
    </component>
    
    <set name="roles" table="user_roles" lazy="false">
      <key column="login" property-ref="login" />
      <element column="role" type="com.test.hibernate.HibernateUserRole" />
    </set>

  </class>

</hibernate-mapping>

Unfortunately, I've tried a bunch of variations but I still can get the query to work (various exceptions based on the current query attempt). Here's is a sample usage:

Code between sessionFactory.openSession() and session.close():

Code:

Criteria crit = session.createCriteria(User.class);

// magic code to allow me to return only those users with a specificed role(s) ...
// something like: 
Disjunction or = Expression.disjunction();
or.add(Expression.eq("???", UserRole.ADMIN);
or.add(Expression.eq("???", UserRole.READER);
crit.add(or);

// end ...

// should contain User instances
List list = crit.list();  

Name and version of the database you are using: MySQL 4.1.10

tenwit · **Joined:** Thu Dec 23, 2004 9:08 pm **Posts:** 2008

I'm pretty sure that you can't query on a collection of values, only entities. Not even in HQL. You'll have to map your enum as a class, then convert it to an enum in your User object. That is, the collection in User that hibernate writes to/reads from is a collection of UserRoleClass objects, but you can provide mehtods like

Code:

public List<UserRole> getUserRoles() {
  List<UserRole> roles = new ArrayList<UserRole>(getInternalRoles().size());
  for (UserRoleClass r : getInternalRoles())
  {
    roles.add(Enum.valueOf(UserRole.class, r.getEnumName());
  }
  return roles;
}

Where r.getEnumName() is a method in your mapped class that returns the name of the associated Enum instance (e.g. ADMIN or READER, from your example).

It's a pain, and we do see questions about it on the forum quite a lot.