Class DistanceHaversineJdbcFunction

java.lang.Object
ch.tocco.nice2.persist.core.api.hibernate.query.AbstractJdbcFunction
ch.tocco.nice2.optional.geolocation.impl.jdbc.DistanceHaversineJdbcFunction
All Implemented Interfaces:
JdbcFunction

@Component public class DistanceHaversineJdbcFunction extends AbstractJdbcFunction

Writes the Haversine function using SQL functions. The function calculates the distance between two points on earth's surface. This can then be used to create queries that filter on distances.

The formula itself:

   RADIUS_EARTH * 2 * ASIN(MIN(1, SQRT(POW(SIN((lat2-lat1) / 2),2) + COS(lat1) * COS(lat2) * POW(SIN((lng2-lng1)/2), 2))))
 

It needs 4 arguments (exactly) and expects it in the following order:

   latitude1, longitude1, latitude2, longitude2
 

Where (latitude1, longitude1) name the first points coordinates and (latitude2, longitude2) name the second points coordinates. The coordinates are assumed to be given in RAD.

For example, consider the following query:


    Query q = ctx.compileQuery("find Cities where DISTANCE(pos_lat, pos_lng, :lat, :lng) < :dst");
    Position zurich = new Position(...);
    q.setParameter("pos_lat", zurich.getLatitude());
    q.setParameter("pos_lng", zurich.getLongitude());
    q.setParameter("dst", Distance.kilometer("15").getKm());
 

This will select all cities that are at maximum 15km away from Zurich (assuming that the "Cities" entity has two fields "pos_lat" and "pos_lng" of respective type.)

  • Field Details

    • EARTH_RADIUS_KM

      public static final BigDecimal EARTH_RADIUS_KM
    • EARTH_RADIUM_MILES

      public static final BigDecimal EARTH_RADIUM_MILES
  • Constructor Details

    • DistanceHaversineJdbcFunction

      public DistanceHaversineJdbcFunction(TypeManager typeManager)
  • Method Details

    • createFunction

      public org.hibernate.dialect.function.SQLFunction createFunction(org.hibernate.type.TypeResolver typeResolver, SqlWriter sqlWriter)
      Returns:
      an SQLFunction that contains the raw sql statement that is executed on the db.
      See Also:
      • SQLFunctionTemplate
    • validateArguments

      public void validateArguments(javax.persistence.criteria.Expression<?>[] arguments) throws JdbcFunctionException
      Throws:
      JdbcFunctionException
    • argumentCount

      public int argumentCount()
      Returns:
      the number of expected arguments.
    • argumentOrder

      public int[] argumentOrder()
      Description copied from interface: JdbcFunction
      Order of parameters as required in SQL statement. This method must be implemented when the order or count of query parameters is different to the SQL parameters. The returned array lists indices of params in order as they are used for the SQL query.
    • setEarthRadius

      public void setEarthRadius(BigDecimal earthRadius)