calculating distance between two coordinates SQL + Criteria Builder

Question

So in my code i want to be able to check what coordinates are in range with some reference coordinates. At the begining i was using some native SQL query like:

  @Query(
          value = "SELECT * FROM event " +
                  "   inner join event_location location on location.id = event.location_id\n" +
                  "  where Round( ST_Distance_Sphere(\n" +
                  "    Point(?1 , ?2 )," +
                  "    Point(location.longtitude , location.latitude ), 4326), 2) <= ?3",
          nativeQuery = true)
  List<Event> findAllEventsInRange(double longtitude, double latitude, String range);

It was working pretty well, but now i would like to use Specification with criteria builder. And to be honest i dont know how i can write condition after where keyword.

Can anyone let me know how i can do it?

EDIT: Entities are definied. And i already created specification which is for now joining two tables - event and event location:

public static Specification<Event> filter(Search search){
return (root, cq, cb) -> {
      Predicate location = null;

      List<Predicate> result = new ArrayList<>();

      if(search.getLat() != null && search.getLng() != null && search.getRange() != null) {
         Join<Event,EventLocation> join = root.join("eventLocation", JoinType.LEFT);
            }

            return cb.and(result.toArray(new Predicate[result.size()]));
        };
    }

And now i need to create a proper predicate which will do the same thing as statement after WHERE. I know there is function on criteria builder which can be used for some native sql function but not sure how i can use it in my case and combine with different other sql functions as well.

Answer 1

You need to use the generic function invocation syntax for this, which would look something like the following:

public static Specification<Event> filter(Search search){
    return (root, cq, cb) -> {
      Predicate location = null;

      List<Predicate> result = new ArrayList<>();

      if(search.getLat() != null && search.getLng() != null && search.getRange() != null) {
         Join<Event,EventLocation> join = root.join("eventLocation", JoinType.LEFT);
         result.add(
           cb.le(
             cb.function("Round", String.class,
               cb.function("ST_Distance_Sphere", String.class, 
                 cb.function("Point", String.class, 
                   cb.literal(search.getLat()),
                   cb.literal(search.getLng())
                 ),
                 cb.function("Point", String.class, 
                   join.get("longtitude"),
                   join.get("latitude ")
                 ),
                 cb.literal(4326)
               ),
               cb.literal(2)
             ),
             cb.literal(search.getRange())
           )
         );
      }
  
      return cb.and(result.toArray(new Predicate[result.size()]));
   };
}