使用 Criteria API 进行算术日期运算

Question

我想使用 Criteria API 进行日期算术运算。例如，在 Postgres 中我可以编写这样的查询：

select * from appointment a where a.date + interval '2 days' > '2022-10-21';

如何使用 Criteria 实现此语法？我是否必须编写自己的 Expression 类，或者是否有任何内置的东西可供我使用？

我尝试了这样的方法，但没有成功：

private class DateArithmetricExpression<T extends Date> extends ExpressionImpl<T> {

        private final int value;
        private final ChronoUnit unit;
        private final BinaryArithmeticOperation.Operation operator;
        private final Expression<T> date;

        public DateArithmetricExpression(CriteriaBuilderImpl cb, Class<T> clazz, Expression<T> date, BinaryArithmeticOperation.Operation operator, int value, ChronoUnit unit) {
            super(cb, clazz);
            this.value = value;
            this.unit = unit;
            this.operator = operator;
            this.date = date;
        }

        @Override
        public void registerParameters(ParameterRegistry registry) {

        }

        @Override
        public String render(RenderingContext renderingContext) {
            String op = switch (operator) {
                case ADD -> "+";
                case SUBTRACT -> "-";
                default -> throw new UnsupportedOperationException();
            };
            String renderedDateExpr = ((Renderable) this.date).render(renderingContext);
            return "%s %s interval '%d %s'".formatted(renderedDateExpr, op, value, unit.toString());
        }
    }

Answer 1

你可以这样做：

    CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
    CriteriaQuery<Appointment> criteriaQuery = criteriaBuilder.createQuery(Appointment.class);
    Root<Appointmet> itemRoot = criteriaQuery.from(Appointmet.class);
    criteriaQuery.where(
            criteriaBuilder.greaterThan(
                    criteriaBuilder.function("sql", Date.class, "? + INTERVAL '2 days'", itemRoot.get("date")),
                    criteriaBuilder.literal(new Date(2022, Calendar.NOVEMBER, 21)))
    );

    TypedQuery<Apppointment> query = entityManager.createQuery(criteriaQuery);
    return query.getResultList();