Hibernate query for multiple items in a collection

Question

I have a data model that looks something like this:

public class Item {
    private List attributes;
    // other stuff
}

public class Item         


        

Answer 1

I didn't test it, but this is how I should try to solve your problem if I would have to:

Map<String,String> map1 = new TreeMap<String,String>();  
map1.put("ia.name","foo1");  
map1.put("ia.value","bar1");  
Map<String,String> map2 = new TreeMap<String,String>();  
map2.put("ia.name","foo2");  
map2.put("ia.value","bar2");  
return getSession().createCriteria(Item.class)
.createAlias("itemAttributes", "ia")
.add(Restrictions.and()
     .add(Restrictions.allEq(map1))
     .add(Restrictions.allEq(map2))
)
.list();

Please, let me know if it worked. I think the same should work with or()...

Answer 2

Use LEFT_OUTER_JOIN to prevent "WHERE x = 1 AND x = 2" kind of issue

CreateAlias("itemAttributes", "ia", JoinType.LEFT_OUTER_JOIN)

Answer 3

Why wouldn't the following work?

return getSession().createCriteria(Item.class)
    .createAlias("itemAttributes", "ia")
    .add(Restrictions.or()
        .add(Restrictions.conjunction()
            .add(Restrictions.eq("ia.name", "foo1"))
            .add(Restrictions.eq("ia.attributeValue", "bar1")))
        .add(Restrictions.conjunction()
            .add(Restrictions.eq("ia.name", "foo2"))
            .add(Restrictions.eq("ia.attributeValue", "bar2"))))
    .list();

That would be (name=foo1 && attributeValue=bar1) OR (name=foo2 && attributeValue=bar2)

Answer 4

Could you use aliasing to do this?

Criteria itemCriteria = session.createCriteria(Item.class);
itemCriteria.createAlias("itemAttributes", "ia1")
            .createAlias("itemAttributes", "ia2")
            .add(Restrictions.eq("ia1.name", "foo1"))
            .add(Restrictions.eq("ia1.attributeValue", "bar1")))
            .add(Restrictions.eq("ia2.name", "foo2"))
            .add(Restrictions.eq("ia2.attributeValue", "bar2")))

Not sure how hibernate handles joining on the same property twice explicitly like that, maybe worth trying?

Answer 5

SELECT item FROM Item item JOIN item.attributes attr 
    WHERE attr IN (:attrList) GROUP BY item

and then in the Java code:

List<ItemAttribute> attrList = new ArrayList<ItemAttribute>();
attrList.add(..); // add as many attributes as needed
...// create a Query with the above string
query.setParameter("attrList", attrList);