Question

任务是按特定的日期对事件进行分组，为此，我必须将日期从日期中撤出并按日期对记录进行分组。我们曾经使用MySql，并且此代码可以正常工作：

class B : public A
{
    using Base = A;
    //...
}

但是切换到Postgres后，这种方法不起作用。我需要发送类似的内容

public static Specification<AllFile> findByGroup(FileFilter fileFilter) {
    return (Specification<AllFile>) (root, query, cb) -> {
        final Collection<Predicate> predicates = new ArrayList<>();

        if (fileFilter.getStart() != null && fileFilter.getEnd() != null) {
            Date date = new Date(fileFilter.getStart().getTime());
            date.setHours(0);
            date.setMinutes(0);
            date.setSeconds(0);
            date.setDate(1);

            predicates.add(cb.greaterThanOrEqualTo(root.get("created"), date));
            predicates.add(cb.lessThanOrEqualTo(root.get("created"), fileFilter.getEnd()));
        }
        else if(fileFilter.getStart() != null) {
            Date date = new Date(fileFilter.getStart().getTime());
            date.setHours(0);
            date.setMinutes(0);
            date.setSeconds(0);
            date.setDate(1);

            Date newDate = DateUtils.addMonths(date, 1);

            predicates.add(cb.greaterThanOrEqualTo(root.get("created"), date));
            predicates.add(cb.lessThanOrEqualTo(root.get("created"), newDate));
        }

        if (fileFilter.getRoute() != null) {
            predicates.add(cb.equal(root.get("route"), fileFilter.getRoute()));
        }

        if (fileFilter.getDevice() != null) {
            predicates.add(cb.equal(root.get("device"), fileFilter.getDevice()));
        }

        if (fileFilter.getType() != null) {
            predicates.add(cb.equal(root.get("type"), fileFilter.getType()));
        }

        if (fileFilter.getUser() != null) {
            predicates.add(cb.equal(root.get("user"), fileFilter.getUser()));
        }

        if (fileFilter.getDeleted() != null) {
            predicates.add(cb.equal(root.get("deleted"), fileFilter.getDeleted()));
        }



        query.groupBy(cb.function("day", Date.class, root.get("created")));
        return cb.and(predicates.toArray(new Predicate[predicates.size()]));
    };
}

代替此

select extract(day from allfile0_.created) as dd
from all_file allfile0_ 
where allfile0_.created>='Tue Oct 01 00:00:00 MSK 2019' and allfile0_.created<='Fri Nov 01 00:00:00 MSK 2019' 
group by dd

是否可以使用Criteria API获得我想要的东西？寻求有关自定义选择的建议，以仅选择我需要的东西。

Answer 1

更改

query.groupBy(cb.function("day", Date.class, root.get("created")));

到

query = cb.createTupleQuery();
    root = query.from(AllFile.class);
    query.select(root.get("created")).
            groupBy(cb.function("day", Integer.class, root.get("created")));

此后，代码将按预期工作

JPA和Criteria API特定选择，使用select提取

1 个答案: