带变量的注解参数

Question

在我们的 Spring 项目中，我想将 Java 存储库转换为 Kotlin。 Repository 是一个带有方法和注释的接口，其中包含数据库查询作为参数。有几种方法，但重复了查询中最复杂和最长的部分。在 Java 中，我们将一个字符串作为变量插入到查询中。

Kotlin 中的当前解决方案无法编译，因为 'an annotation argument must be a compile-time constant'。

处理此问题的最佳方法是什么？

interface PlaceRepository : JpaRepository<Place, UUID>, JpaSpecificationExecutor<Place> {

    val HAVERSINE_FORMULA: String
        get() =
            """
                (6371 * acos(cos(radians(CAST(CAST(:latitude AS string) AS double)))
                * cos(radians(p.gpsLatitude)) * cos(radians(p.gpsLongitude) - radians(CAST(CAST(:longitude AS string) AS double)))
                + sin(radians(CAST(CAST(:latitude AS string) AS double))) * sin(radians(p.gpsLatitude))))
            """

    @Query("""
        SELECT p AS place,
             $HAVERSINE_FORMULA AS distance
        FROM Place p
        WHERE p.code = :code
    """)
    fun findByCode(
        code: String,
        latitude: Double,
        longitude: Double
    ): Optional<PlaceWithDistanceDTO>
}

谢谢

Answer 1

您可以尝试如下使用伴生对象：

interface PlaceRepository : JpaRepository<Place, UUID>, JpaSpecificationExecutor<Place> {

    companion object {
        private const val HAVERSINE_FORMULA =
            """
                (6371 * acos(cos(radians(CAST(CAST(:latitude AS string) AS double)))
                * cos(radians(p.gpsLatitude)) * cos(radians(p.gpsLongitude) - radians(CAST(CAST(:longitude AS string) AS double)))
                + sin(radians(CAST(CAST(:latitude AS string) AS double))) * sin(radians(p.gpsLatitude))))
            """
    }

    @Query("""
        SELECT p AS place,
             $HAVERSINE_FORMULA AS distance
        FROM Place p
        WHERE p.code = :code
    """)
    fun findByCode(
        code: String,
        latitude: Double,
        longitude: Double
    ): Optional<PlaceWithDistanceDTO>
}

带变量的注解参数

Annotation argument with variable

annotations

jpa

kotlin