Querying Hibernate Parent/Child with Subquery Criteria
EDIT: relevant: https://forum.hibernate.org/viewtopic.php?f=1&t=946236&start=0 but still no solution there.
I have a parent/child relationship. The parent maps a set of string tags. The simplified DDL:
CREATE TABLE PARENT (
ID NUMBER(38,0) NOT NULL,
{other columns here}
CONSTRAINT PK_PARENT PRIMARY KEY ("ID")
)
CREATE TABLE TAGS (
PARENT_ID NUMBER(38,0) NOT NULL,
NAME VARCHAR2(100) NOT NULL,
CONSTRAINT CHILD_PARENT_FK FOREIGN KEY ("PARENT_ID") REFERENCES PARENT("ID")
)
The child table has a foreign key to the parent table, and a varchar called name.
The parent class maps the child as a Set
public class Parent {
public Set<String> getTags() { return tags; }
public void setTags(Set<String> tags) { this.tags = tags; }
}
The mapping
<class name="com.example.Parent" table="parent">
<set name="tags" table="tags" order-by="name asc">
<key column="parent_id"/>
<element type="string" column="name"/>
</set>
</class>
This sqlRestriction query does exactly what I want to do:
return session.createCriteria(Parent.class)
.add(Restrictions.sqlRestriction(
"EXISTS (SELECT 1 FROM tags t WHERE t.parent_id = {alias}.id "+
"AND t.name in ('tag1', 'tag2', 'tag3') )" ) );
This finds me all Parent objects that have tags that match any of 'tag1', 'tag2', 'tag3'.
I need to translate this into a Criteria based query b/c we use Criteria for all the other properties, and I need to find a way to do the same for this: essentially convert this into a Criterion or a DetachedCriteria that I can use as part of a larger expression .
The problem I am having is that most examples that are similar have a Parent and Child Entity class, where the child class is a bona-fide entity. You can thus create Criteria like:
session.createCriteria(Parent.class, "p").createCriteria("tags").etc...
If I try to do this, Hibernate throws a mapping exception and complains that "tags" is not an association. The mapping is correct, however. If I query for parent types, it returns me the child tags just fine in the Set -- I just can't figure out how to query it with some combination of Criteria, Subqueries, Restrictions, DetachedCriteria, etc.
I would love to hear any suggestions.
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