LocalDate between using JPA 2.1 Criteria API

问题

In my entity I have two fields :

private LocalDate startDate = LocalDate.of(1900, 1, 1);
private LocalDate endDate = LocalDate.of(3000, 1, 1);

Using JPA Criteria API I want to select entities where LocalDate.now() > startDate and LocalDate.now() < endDate.

I tried as following :

predicates.add(builder.greaterThan(LocalDate.now(), path.<LocalDate> get(Entity_.startDate)));
predicates.add(builder.lessThan(builder.currentDate(), path.<LocalDate> get(Entity_.endDate)));

But I get this error :

The method greaterThan(Expression<? extends Y>, Expression<? extends Y>) in the type CriteriaBuilder is not applicable for the arguments (LocalDate, Path<LocalDate>)

I tried this too :

predicates.add(builder.between(builder.currentDate(), path.<LocalDate> get(Entity_.startDate), path.<LocalDate> get(Entity_.endDate)));

Where I get the following error :

The method between(Expression<? extends Y>, Expression<? extends Y>, Expression<? extends Y>) in the type CriteriaBuilder is not applicable for the arguments (Expression<Date>, Path<LocalDate>, Path<LocalDate>)

How can I solve this ?

回答1:

It seems that you need an AttributeConverter since JPA 2.1 does not yet support LocalDate directly. Assuming you have an Entity like

@Entity
@Getter
public class LocalDateEntity {
   @Id
   @GeneratedValue
   private Long id;
   @Setter
   private LocalDate startDate = LocalDate.of(1900, 1, 1);
   @Setter
   private LocalDate endDate = LocalDate.of(3000, 1, 1);
}

you can use AttributeConverter like

// import java.sql.Date not java.util.Date;
@Converter(autoApply = true) // this makes it to apply anywhere there is a need
public class LocalDateConverter implements AttributeConverter<LocalDate, Date> {

   @Override
   public Date convertToDatabaseColumn(LocalDate date) {
      return Date.valueOf(date);
   }

   @Override
   public LocalDate convertToEntityAttribute(Date value) {      
      return value.toLocalDate();
   }
}

after that it is possible to make CriteriaQuery like

CriteriaBuilder cb = em.getCriteriaBuilder();
CriteriaQuery<LocalDateEntity> cq = cb.createQuery(LocalDateEntity.class);
Root<LocalDateEntity> from = cq.from(LocalDateEntity.class);
Expression<Date> expCurrDate = cb.currentDate();
cq.where(
      cb.and(
            cb.greaterThan(from.get("endDate"), expCurrDate)
            ,cb.lessThan(from.get("startDate"), expCurrDate)
           // OR for example
           // cb.lessThan(expCurrDate, from.get("endDate"))
           // ,cb.greaterThan(expCurrDate, from.get("startDate"))
           // both are expressions no matter in what order
           // but note the change in Predicate lt vs. gt
      )
);
TypedQuery<LocalDateEntity> tq = em.createQuery(cq);

NOTE: while Predicate between(..) will also work but a bit different. It includes the starting & ending dates.

来源：https://stackoverflow.com/questions/47928424/localdate-between-using-jpa-2-1-criteria-api

标签

java

jpa

jpa-2.1

jpa-criteria