[英]calculating distance between two coordinates SQL + Criteria Builder
所以在我的代碼中,我希望能夠使用一些參考坐標檢查哪些坐標在范圍內。 一開始我使用的是一些本機 SQL 查詢,例如:
@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);
它工作得很好,但現在我想將規范與標准構建器一起使用。 老實說,我不知道如何在 where 關鍵字之后寫條件。
誰能讓我知道我該怎么做?
編輯:實體已定義。 而且我已經創建了現在加入兩個表的規范 - 事件和事件位置:
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()]));
};
}
現在我需要創建一個正確的謂詞,它將與 WHERE 之后的語句執行相同的操作。 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.
為此,您需要使用通用的 function 調用語法,如下所示:
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()]));
};
}
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