如何构建动态查询,添加日期天数并使用条件API将该日期与另一个日期进行比较？

我有一张A桌和一张B桌. JPA实体,A和B类都有joda.time.datetime持久字段分别表示retentionDate和lastmodifiedDate. A还有一个类型为int的持久字段.现在我想将a.days的数量添加到a.retentionDate中,然后使用JPA criteria API将其与b.lastmodifiedDate进行比较.

实体类

@Entity
@Table(name = "A")
@Data
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@EqualsAndHashCode(of = "id", callSuper = false)
public class A extends AbstractBaseEntity {
    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    @Column(unique = true, length = 36)
    private String id;

    @Type(type = "org.jadira.usertype.dateandtime.joda.PersistentDateTime")
    @JsonDeserialize(using = DateTimeDeserializer.class)
    @JsonSerialize(using = DateTimeSerializer.class)
    private DateTime retentionDate;

    private int days;
}

B实体类

@Entity
@Table(name = "B")
@Data
@JsonInclude(JsonInclude.Include.NON_NULL)
@JsonIgnoreProperties(ignoreUnknown = true)
@EqualsAndHashCode(of = "id", callSuper = false)
public class B extends AbstractBaseEntity {
    @Id
    @GeneratedValue(generator = "uuid")
    @GenericGenerator(name = "uuid", strategy = "uuid2")
    @Column(unique = true, length = 36)
    private String id;

    @Type(type = "org.jadira.usertype.dateandtime.joda.PersistentDateTime")
    @JsonDeserialize(using = DateTimeDeserializer.class)
    @JsonSerialize(using = DateTimeSerializer.class)
    private DateTime lastmodifiedDate ;

   @ManyToOne(fetch = FetchType.EAGER)
   @JoinColumn(name = "A_ID")
   private A a;
}

JPA标准查询：

CriteriaQuery<B> b = builder.createQuery(B.class);
Root<B> fromB = criteria.from(B.class); 
Expression<DateTime> lastmodifiedDate = fromB.get(B_.lastmodifiedDate);
Expression<DateTime> retentionDate = fromB.get(B_.a).get("retentionDate");
Expression<int> days = fromB.get(B_.a).get("days");
Expression<DateTime> newDate = // how to add days in retentionDate here so it became a newDate?
b.select(fromB);
b.where(builder.greaterThanOrEqualTo(newDate , lastmodifiedDate)
);

请帮助我在上面的查询中添加retentionDate中的天数.谢谢.

解决方法:

您可以使用CriteriaBuilder#function()执行数据库功能以将天数添加到retentionDate中.
我用DATEADD()做了一个例子,因为我的测试项目是用H2数据库运行的.

    ParameterExpression<String> dayUnit = builder.parameter(String.class, "dayUnit");
    Expression<DateTime> newDate = builder.function("DATEADD", DateTime.class, dayUnit, days, retentionDate);

完整的例子：

    CriteriaBuilder builder = entityManager.getCriteriaBuilder();
    CriteriaQuery<B> cq = builder.createQuery(B.class);
    Root<B> fromB = cq.from(B.class);

    Expression<DateTime> lastmodifiedDate = fromB.get(B_.lastmodifiedDate);
    Expression<DateTime> retentionDate = fromB.get(B_.a).get("retentionDate");
    Expression<Integer> days = fromB.get(B_.a).get("days");

    ParameterExpression<String> dayUnit = builder.parameter(String.class, "dayUnit");
    Expression<DateTime> newDate = builder.function("DATEADD", DateTime.class, dayUnit, days, retentionDate);

    cq.where(builder.greaterThanOrEqualTo(newDate, lastmodifiedDate));

    TypedQuery<B> tq = entityManager.createQuery(cq.select(fromB));
    tq.setParameter("dayUnit", "DAY");
    List<B> results = tq.getResultList();

此查询转换为SQL为：

select 
    b0_.id as id1_1_, 
    b0_.a_id as a_id3_1_, 
    b0_.lastmodified_date as lastmodi2_1_ 
from b b0_ 
    cross join a a1_ 
where b0_.a_id=a1_.id 
    and DATEADD(?, a1_.days, a1_.retention_date)>=b0_.lastmodified_date

标签：java,jpa,hibernate,hibernate-criteria,criteria-api
来源： https://codeday.me/bug/20190701/1348897.html