Question

I am struggling to create a query using the Criteria API. The following SQL query returns the result that I need:

SELECT * FROM MODEL WHERE MANUFACTURER_ID = 1 AND SHORTNAME LIKE '%SF%' OR LONGNAME LIKE '%SF%';

I have written the following code using the criteria API:

public List<Model> findAllByManufacturer(Manufacturer manufacturer,
        String pattern) {
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<Model> cq = cb.createQuery(Model.class);
    Root<Model> m = cq.from(Model.class);
    cq.select(m);
    Join<Model, Manufacturer> mf = m.join("manufacturer");
    Predicate p = cb.equal(mf.get("id"), manufacturer.getId());
    p = cb.and(cb.like(cb.upper(m.<String>get("shortName")),
            pattern.toUpperCase()));
    p = cb.or(cb.equal(cb.upper(m.<String>get("longName")),
            pattern.toUpperCase()));
    cq.where(p);
    return em.createQuery(cq).getResultList();
}

When I think about it logically, it should work:

Predicate p = cb.equal(mf.get("id"), manufacturer.getId());

WHERE MANUFACTURER_ID = 1

p = cb.and(cb.like(cb.upper(m.<String>get("shortName")),
                pattern.toUpperCase()));

AND SHORTNAME LIKE ‘%SF%’

p = cb.or(cb.equal(cb.upper(m.<String>get("longName")),
                pattern.toUpperCase()));

OR LONGNAME LIKE ‘%SF%’

The query does properly run in that I am not getting any errors, it just is not returning any results. Any clue on where I went wrong are very much appreciated!

Answer 1

Have you checked the generated SQL?

You’re building a predicate and assigning it to p, but then you’re creating another one and assign it to the same p variable.

I think it should rather be:

Predicate predicateOnManufacturerId = cb.equal(mf.get("id"), 
                                               manufacturer.getId());
Predicate predicateOnShortName = cb.like(cb.upper(m.<String>get("shortName")),
                                         pattern.toUpperCase()));
Predicate predicateOnLongName = cb.equal(cb.upper(m.<String>get("longName")),
                                         pattern.toUpperCase()));
Predicate p = cb.or(cb.and(predicateOnManufacturerId, 
                           predicateOnShortName),
                    predicateOnLongName);
cq.where(p);

Also, why don’t you use the meta-model of your entities:

Join<Model, Manufacturer> mf = m.join(Model_.manufacturer);
... cb.equal(mf.get(Manufacturer_.id);
...

It would be more type-safe, and you would detect incorrect queries at compilation time rather than runtime.