如何在QueryDSL中创建OrderSpecifier以获得时间差异？

Question

我想创建一个querydsl OrderSpecifier表达式，该表达式按两个sql TIME值的分钟差OrderSpecifier ：

@Generated
public class QStock extends EntityPathBase<Stock> {
    public final TimePath<java.time.LocalTime> time1 = createTime(..);
    public final TimePath<java.time.LocalTime> time2 = createTime(..);
}

伪代码：

QStock.stock.time1.minutesTo(QStock.stock.time2).desc();

当然， minutesTo()方法不存在。 但是我该如何实现呢？

当然，不需要以分钟为单位计算差异。 我只想将这2次自上而下排序之间的最大差异。

我尝试如下，但遇到异常：

Expressions.numberOperation(Integer.class, Ops.DateTimeOps.DIFF_MINUTES, QStock.stock.time1, QStock.stock.time2)


Caused by: java.sql.SQLSyntaxErrorException: (conn=1326) FUNCTION table.diff_minutes does not exist
    at org.mariadb.jdbc.internal.util.exceptions.ExceptionMapper.get(ExceptionMapper.java:236) ~[mariadb-java-client-2.3.0.jar:?]
    at org.mariadb.jdbc.internal.util.exceptions.ExceptionMapper.getException(ExceptionMapper.java:165) ~[mariadb-java-client-2.3.0.jar:?]

所以我尝试将TIMEDIFF函数字符串显式添加到querydsl：

//inspired by Ops.DateTimeOps
enum MysqlDateTimeOps implements Operator {
    TIMEDIFF(Comparable.class);

    private final Class<?> type;

    MysqlDateTimeOps(Class<?> type) {
        this.type = type;
    }

    @Override
    public Class<?> getType() {
        return type;
    }
}

使用方法：

Expressions.numberOperation(Integer.class, MysqlDateTimeOps.TIMEDIFF, QStock.stock.time1, QStock.stock.time2)

结果：

org.springframework.dao.InvalidDataAccessApiUsageException: No pattern found for TIMEDIFF; nested exception is java.lang.IllegalArgumentException: No pattern found for TIMEDIFF
    at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:373) ~[spring-orm-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:255) ~[spring-orm-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:527) ~[spring-orm-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61) ~[spring-tx-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:242) ~[spring-tx-5.1.9.RELEASE.jar:5.1.9.RELEASE]
    at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:153) ~[spring-tx-5.1.9.RELEASE.jar:5.1.9.RELEASE]

那么，如何在TIMEDIFF使用TIMEDIFF函数呢？

Answer 1

尽管我希望有一个更简单的解决方案，但仍可以进行以下工作：

Expressions.timeTemplate(Integer.class, "TIMEDIFF({0}, {1})", Arrays.asList(QStock.stock.time1, QStock.stock.time2));