如何在谓词中使用if/else语句？

Question

这里有一段代码：

final CriteriaBuilder builder = JPA.em().getCriteriaBuilder();
    final CriteriaQuery<Ticket> criteria = builder.createQuery(Ticket.class);
    Root<Ticket> ticketRoot = criteria.from(Ticket.class);
    Join<Ticket, Order> order = ticketRoot.join("order", JoinType.LEFT);
    Join<Ticket, EventGroup> eventGroups = ticketRoot.join("eventGroup", JoinType.LEFT);
    final List<javax.persistence.criteria.Predicate> predicates = new ArrayList<>();


if (from != null) {
        predicates.add(
            builder.or(
                builder.greaterThanOrEqualTo(order.get("completedOn"), from),
                builder.greaterThanOrEqualTo(ticketRoot.get("refundedAt"), from))
        );
      }

它现在查找具有completedon或日期在from之后的refundedat的票据。我想改变这个。

Answer 1

您是否尝试使用selectcase，如下所示：

predicates.add(
    (Predicate)
    builder.selectCase()
           .when(
               builder.isNotNull(ticketRoot.get("refundedAt")), 
               builder.greaterThanOrEqualTo(ticketRoot.get("refundedAt"), from)
           )
           .otherwise(builder.greaterThanOrEqualTo(order.get("completedOn"), from))
           .as(Boolean.class));

);