JPA2 API Criteria runtime cast from varchar (25) to decimal

Question

So, I saw all the threads when the stack overflowed on similar topics, but I did not find a solution for my problem.

I try to create a Criteria query and I get this SQL (1st SQL, simplified):

SELECT latitude FROM stations WHERE (ABS(latitude - 45.893227) <= 0.2)

but he gives me this error:

java.sql.SQLDataException: The resulting value is outside the range for the data type DECIMAL/NUMERIC(31,31).

This is because my latitude is of type varchar (25). So this fixes (2nd SQL):

SELECT latitude FROM stations WHERE (ABS(CAST(latitude AS DECIMAL) - 45.893227) <= 0.2)

But now I need to do this in Criteria syntax. This is my method:

public List<Stations> searchStations(Float distance, List<Address> addresses) {
    CriteriaBuilder cb = em.getCriteriaBuilder();
    CriteriaQuery<Stations> cq = cb.createQuery(Stations.class);
    Root<Stations> stations = cq.from(Stations.class);

    //this <Float> cast actually does nothing:
    Expression<Float> Lat = stations.get("latitude");
    Expression<Float> Lon = stations.get("longitude");

    //make a list of conditions
    List<Predicate> predicates = new ArrayList<>();
    for (Address a : addresses) {
        Float aLat = Float.valueOf(a.getLatitude());
        Float aLon = Float.valueOf(a.getLongitude());


        //condition: |station.Lat - address.Lat| <= distance
        //le() = lessThan, abs() = absolute, diff() = subtraction

        Predicate condLat = cb.le(cb.abs(cb.diff(Lat, aLat)), distance);
        Predicate condLon = cb.le(cb.abs(cb.diff(Lon, aLon)), distance);

        //if I do: Lat.as(Float.class) it won't cast on runtime!

        predicates.add(condLat);
        predicates.add(condLon);
    }

    //add the array of conditions to the WHERE expression, connected with AND:
    cq.where(cb.and(predicates.toArray(new Predicate[predicates.size()])));

    TypedQuery<Stations> q = em.createQuery(cq);
    return q.getResultList();
}

With this code, I get the first SQL, and I want the second. I just can't get this runtime functionality. The selection functions of the Criteria type that I tried do not work at runtime. How do I solve this problem?

Answer 1

CriteriaBuilder java derby DOUBLE:

    Expression Lat = stations.get("latitude");

    Expression LatCast = cb.function("DOUBLE", Float.class, Lat);

SQL:

DOUBLE(LATITUDE)

: http://www.javadb.net/double-function.html, http://www.objectdb.com/api/java/jpa/criteria/CriteriaBuilder/function_String_Class__Expression__

.