如何构建一个动态查询，添加迄今为止的天数并使用标准 API 将该日期与另一个日期进行比较？

Question

我有一张A表和一张B表。两者JPA entity，A和B类已经joda.time.datetime Persistent Field说的retentionDate和lastmodifiedDate分别。A还有一个Persistent Field类型int说days。现在我想add number of a.days进入a.retentionDate然后将它与b.lastmodifiedDate使用JPA criteria API.

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 条件查询：

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)
);

请帮助我在上述查询中添加保留日期中的天数。谢谢你。

Answer 1

您可以使用CriteriaBuilder#function()执行数据库函数以添加days到retentionDate. 我用DATEADD()做了一个例子，因为我的测试项目使用 H2 数据库运行。

    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();

该查询转换为 SQL 如下：

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