Date comparison using the JPA criteria API

问题

I got a range date picker with two dates: start and end, where both can be empty. I would like to filter a table, where the entity has exact one date: date.

So, here are some examples. I'd like to match. Imaging the date to match is the current date (17/07/2016).

null - 17/07/2016 -> match
17/07/2016 - null -> match
17/07/2016 - 17/07/2016 -> match
null - null -> match all

Those are the edge cases in my opinion and the reason why I am struggling so much.

Actually my code looks like:

CriteriaBuilder cb = getEm().getCriteriaBuilder();
CriteriaQuery<Transaction> cq = cb.createQuery(Transaction.class);
Root<Transaction> root = cq.from(Transaction.class);

List<Predicate> predicates = new ArrayList<>();

Predicate startPredicate = cb.greaterThanOrEqualTo(root.get(Transaction_.date), start);
Predicate endPredicate = cb.greaterThanOrEqualTo(root.get(Transaction_.date), end);

predicates.add(startPredicate);
predicates.add(endPredicate);
cq.select(root).where(predicates.toArray(new Predicate[] {}));

TypedQuery<Transaction> query = getEm().createQuery(cq);
query.setFirstResult(firstRow);
query.setMaxResults(maxRow);
List<Transaction> resultList = query.getResultList();

I'd like to get a query like this:

SELECT * FROM transaction
WHERE ((cast(date AS DATE) >= '2016-07-16' OR cast(date AS DATE) IS NULL))
       AND ((cast(date AS DATE) <= '2016-07-17' OR cast(date AS DATE) IS NULL))

Please note: The static date is to simulate a start and end date. and date is the table column.

I know that my code is wrong. It matches only ranges, without considering null values. Also, if start and end is the same day, I will get zero results.

Do you have you any idea? How can I edit my code to match all the mentioned patterns?

回答1:

I have an existing database table named discount with two columns of type TIMESTAMP named discount_start_date and discount_end_date in a MySQL database. So, please adjust your query according to the name of the table and respective columns in that table.

The complete criteria query based on the SQL statement given in the question can be constructed as follows (I hope the code would be self-explanatory).

CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
CriteriaQuery<Discount> criteriaQuery = criteriaBuilder.createQuery(Discount.class);
Root<Discount> root = criteriaQuery.from(entityManager.getMetamodel().entity(Discount.class));

SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MM-yyyy");
java.util.Date startDate = dateFormat.parse("24-02-2016");
java.util.Date endDate = dateFormat.parse("24-03-2016");

ParameterExpression<java.util.Date> parameter = criteriaBuilder.parameter(java.util.Date.class);

Predicate startDatePredicate = criteriaBuilder.greaterThanOrEqualTo(root.get(Discount_.discountStartDate).as(java.sql.Date.class), parameter);
Predicate endDatePredicate = criteriaBuilder.lessThanOrEqualTo(root.get(Discount_.discountEndDate).as(java.sql.Date.class), parameter);

Predicate startDateOrPredicate = criteriaBuilder.or(startDatePredicate, root.get(Discount_.discountStartDate).isNull());
Predicate endDateOrPredicate = criteriaBuilder.or(endDatePredicate, root.get(Discount_.discountEndDate).isNull());

Predicate and = criteriaBuilder.and(startDateOrPredicate, endDateOrPredicate);
criteriaQuery.where(and);

List<Discount> list = entityManager.createQuery(criteriaQuery)
        .setParameter(parameter, startDate, TemporalType.DATE)
        .setParameter(parameter, endDate, TemporalType.DATE)
        .getResultList();

It produces the following SQL query of your interest (both fields are inclusive as you stated).

select
    discount0_.discount_id as discount1_15_,
    discount0_.discount_code as discount2_15_,
    discount0_.discount_end_date as discount3_15_,
    discount0_.discount_percent as discount4_15_,
    discount0_.discount_start_date as discount5_15_ 
from
    project.discount discount0_ 
where
    (
        cast(discount0_.discount_start_date as date)>=? 
        or discount0_.discount_start_date is null
    ) 
    and (
        cast(discount0_.discount_end_date as date)<=? 
        or discount0_.discount_end_date is null
    )

Tested on Hibernate 4.3.6 final but average ORM frameworks should produce the same query without any modifications.

In this method setParameter(parameter, startDate, TemporalType.DATE), the last parameter i.e. TemporalType.DATE is only needed, if you have a column of type DATETIME or TIMESTAMP in your database and you want to compare dates ignoring the time portion of such columns. You can simply exclude that parameter, if your columns do not have a time portion like DATE (MySQL).

You can, if necessary, also use other date (time) handling APIs like java.time or JodaTime replacing Date along with SimpleDateFormat

来源：https://stackoverflow.com/questions/38424516/date-comparison-using-the-jpa-criteria-api

标签

date

jpa

criteria-api