如何在 JPA 查询中将 LocalDateTime 转换为 LocalDate？

Question

I have object with field LocalDateTime dateTime . And I have the following repository method

@Query("select m from MyClass m " +
                "where m.dateTime >= :startDate and m.dateTime <= :endDate")
findAllByTradeTimeBetween(@Param("startDate") LocalDate startDate, 
                          @Param("endDate") LocalDate endDate);

How to get LocalDate of LocalDateTime dateTime in this method. Now I have an exception

Parameter value [2020-01-31] did not match expected type [java.time.LocalDateTime]

How can I fix it?

Answer 1

It would seem more strict to keep the query in LocalDateTime, and add an API for LocalDate versions.

@Query("select m from MyClass m " +
                "where m.dateTime >= :startDate and m.dateTime < :endDate")
findAllByTradeTimeBetween(@Param("startDate") LocalDateTime startDate, 
                          @Param("endDate") LocalDateTime endDate);

findAllByTradeTimeBetween(LocalDate startDate, LocalDate endDate) {
    return findAllByTradeTimeBetween(startDate.atStartOfDay(),
                                     endDate.plusDays(1).atStartOfDay());
}

This opens the API for some dubious usage (using LocalDateTimes).

Answer 2

You can use an javax.persistence.AttributeConverter to automate the conversion between the Date formats. Here's the Converter class which will automatically convert the LocalDateTime object to LocalDate and viceversa:

@SuppressWarnings("UnusedDeclaration")
    @Converter(autoApply = true)
    public class LocalDateConverter implements AttributeConverter<LocalDateTime, LocalDate> {
        @Override
        public LocalDate convertToDatabaseColumn(LocalDateTime localDateTime) {
            //convert localDateTime to LocalDate
        }

        @Override
        public LocalDateTime convertToEntityAttribute(LocalDate localDate) {
            // convert localDate to LocalDateTime
        }
    }