自定义方法排序Spring数据JPA

Question

is there possibility to use Java method to sort JPA result?

I have entity:

+--------+----------+-----------+
| Name   | Latitude | Longitude |
+--------+----------+-----------+
| A      | x1       | y1        |
| B      | x2       | y2        |
| C      | x3       | y3        |
+--------+----------+-----------+

I mean instead of writing SQL:

    "  ORDER BY (acos(sin(latitude * $RADIAN) * sin(:latitude * $RADIAN)" +
    "       + cos(latitude * $RADIAN) * cos(:latitude * $RADIAN)" +
    "         * cos((:longitude * $RADIAN) - (longitude * $RADIAN))" +
    "  ) * $EARTH_RADIUS)")
fun findDoctorDepartmentsInRange(@Param("latitude") latitude: Double,
                                 @Param("longitude") longitude: Double)

I've tried with Specification but how to inject custom java method into EXPRESSION used below:

query.orderBy(cb.asc(EXPRESSION))

Answer 1

If you are using Spring JPA, you could use Sort object, and you append it not in your specification but to your query

as far as i remember sntax will be something like that

repository.findAll(specification,  new Sort(Sort.Direction.ASC, "field"));

Edit

I'm not sure is Sort supports expressions, so if you want to do this in java code, you need to create Criteria API query, which will be something like that

CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<SomeClass> query = cb.createQuery(SomeClass.class);
Root<SomeClass> root = query.from(SomeClass.class);
Expression EXPRESSION = <<TypeYourExpression>>;
query.orderBy(cb.asc(EXPRESSION))
query.where(specification.toPredicate(root,query,cb))
List<SomeClass> result = em.createQuery(query).getResultList();

Answer 2

You can't have java code as your ORDER BY expression in general. Not in SQL nor in JPA.

Some databases (at least Oracle) allow you to define Stored Procedures in Java, so in theory, you probably can write an SP in Java and use the that in an ORDER BY expression.