Spring CrudRepository 按结果返回组为 Map

Question

I use CrudRepository to execute a native query, where i use a sum and a group by. I want the query to return the result as a (Hash)Map. My query looks like this:

 @Query(value = "SELECT l.currency, sum(l.price) as total_revenue from line l " + "where ol.id0 = :id0 and l.date_time between :dateStart and :dateEnd and " +
        "(cast(:id1 as text) is null or cast(l.id1 as text) = cast(:id1 as text)) and " +
        "(cast(:id2 as text) is null or cast(l.id2 as text) = cast(:id2 as text))" +
        "group by l.currency" ,
        nativeQuery = true)
List<Object[]> findTotalRevenueByCurrency(@Param("id0") UUID id0,
                                                     @Param("dateStart") Instant dateTimeStart,
                                                     @Param("dateEnd") Instant dateTimeEnd,
                                                     @Param("id1") UUID id1,
                                                     @Param("id2") UUID id2);

This returns a List of Objects that i manually turn to a Map<String, BigDecimal> using the following code:

var result = orderLineRepository.findAveragePriceByCurrency(id0, orderDate.minus(2, DAYS), orderDate.plus(2, DAYS), id1, id2);

Map<String, BigDecimal> revenueByCurrency = result.stream()
    .map(arr -> Map.of((String) arr[0], (BigDecimal) arr[1]))
    .flatMap(m -> m.entrySet().stream())
    .collect(Collectors.toMap(Map.Entry::getKey, Map.Entry::getValue));```

Which is quite brittle and requires casting. Is there a way to let this query return Map<String, BigDecimal> out of the box?

Answer 1

You can create a custom class to match the result of this query then map list of results to Map.

public class CustomQueryResult {
 //class properties
 public CustomQueryResult(String currency, BigDecimal price) {
    //assign 
 }
}
@Query(value = "SELECT new CustomQueryResult(l.currency, sum(l.price) as total_revenue) from line l " + "where ol.id0 = :id0 and l.date_time between :dateStart and :dateEnd and " +
        "(cast(:id1 as text) is null or cast(l.id1 as text) = cast(:id1 as text)) and " +
        "(cast(:id2 as text) is null or cast(l.id2 as text) = cast(:id2 as text))" +
        "group by l.currency" ,
        nativeQuery = true)
List<CustomQueryResult> findTotalRevenueByCurrency(@Param("id0") UUID id0,
                                                     @Param("dateStart") Instant dateTimeStart,
                                                     @Param("dateEnd") Instant dateTimeEnd,
                                                     @Param("id1") UUID id1,
                                                     @Param("id2") UUID id2);

var result = orderLineRepository.findAveragePriceByCurrency(id0, orderDate.minus(2, DAYS), orderDate.plus(2, DAYS), id1, id2);

 Map<String, BigDecimal> revenueByCurrency = result.stream()
                .collect(Collectors.toMap(k -> k.getCurrency(), v -> v.getPrice());