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javax。坚持不懈PersistenceException:组织。冬眠MappingException:未知实体:it。*。PoolStateResult |将结果映射到DTO(非实体)

dto pojo jpa hibernate java

Angelo · 技术社区 · 7 年前

使用:

<dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
            <version>1.5.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
            <version>1.5.8.RELEASE</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <version>1.5.8.RELEASE</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>junit</groupId>
            <artifactId>junit</artifactId>
            <version>4.12</version>
            <scope>test</scope>
        </dependency>

        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-test</artifactId>
            <version>${spring.version}</version>
            <scope>test</scope>
        </dependency>
    </dependencies>

这是我的DTO。它不是DB上的实体。我只想将其用于映射

public class PoolStateResult {

    private Integer totalCodes;
    private Integer assignedCodes;
    private Integer availableCodes;

    private Date startDateValidate;
    private Date endDateValidate;

constructors
getters and setters

这就是道的内容

    Query q = em.createNativeQuery("  SELECT p.start_validity_date as startDateValidate, "
            + " p.end_validity_date as endDateValidate, "
            + " (SELECT count(*) from POOL_CODES p WHERE p.id_pool = :poolCode) as totalCodes, "
            + " (SELECT count(*) "
            + " from VOUCHER v "
            + " WHERE v.id_reference_pool = :poolCode "
            + " AND v.status = 'ASSEGNATO') as assignedCodes, "
            + " (SELECT count(*) "
            + " from VOUCHER v, POOL_CODES p "
            + " WHERE v.id_reference_pool = p.id_pool "
            + " AND v.id_reference_pool = :poolCode "
            + " AND v.status = 'ASSEGNATO' "
            + " and p.end_validity_date < sysdate) as availableCodes "
            + " from POOL_CODES p "
            + " WHERE p.id_pool = :poolCode",PoolStateResult.class);

    q.setParameter("poolCode", "poolCode"); 
    return (PoolStateResult) q.getSingleResult();

我在configuration类中添加此包

entityManagerFactory.setPackagesToScan(
                env.getProperty("entitymanager.packages.to.scan"),

这是个例外

javax.persistence.NoResultException: No entity found for query
    at org.hibernate.jpa.internal.QueryImpl.getSingleResult(QueryImpl.java:532)

对于所有实体表,是否有一种方法可以自动强制映射,或者对于这些类型的查询,使用hibernate的唯一方法是编写映射? 这是使用Hibernate映射非实体Java对象的最佳且唯一的方法吗?

 @SqlResultSetMapping(
               name="getPoolStateResult",
               classes={
                  @ConstructorResult(
                       targetClass=PoolStateResult.class,
                         columns={
                            @ColumnResult(name="totalCodes", type=Integer.class),
                            @ColumnResult(name="assignedCodes", type=Integer.class),
                            @ColumnResult(name="availableCodes", type=Integer.class),
                            @ColumnResult(name="startDateValidate", type=Date.class),
                            @ColumnResult(name="endValidityDate", type=Date.class)
                            }
                  )
               }
              )

那么,在这种情况下,休眠的优势在哪里呢?

谢谢

2 回复 | 直到 7 年前

Thorben Janssen 7 年前

没有任何映射信息,JPA和Hibernate无法将查询结果自动映射到DTO。要么以编程方式映射结果,要么在 @SqlResultSetMapping ,正如您在示例中所做的。

如果要将结果映射到实体,则不需要这样做。然后Hibernate尝试使用实体的映射定义来映射查询结果。因此,查询结果需要返回所有实体属性,并且它们必须与您在实体映射中使用的名称相同。我在 series of blog posts about @SqlResultMapping .

关于使用Hibernate进行此类查询的好处: 如果这是您在事务中执行的唯一数据库交互,那么Hibernate不会给您带来任何好处。但它允许您在Hibernate会话中使用此查询,因此可以在与Hibernate在该会话中执行的所有其他操作相同的事务中使用此查询。

Maciej Kowalski 7 年前

尝试稍微更改您的查询创建:

1) 添加 NEW package.Class 到选择列表

String queryString = 
         "SELECT new com.mypackage.PoolStateResult("
             +  "p.start_validity_date as startDateValidate, "
             + " p.end_validity_date as endValidityDate, "
            + " (SELECT count(*) from POOL_CODES p WHERE p.id_pool = :poolCode) as totalCodes, "
            + " (SELECT count(*) "
            + ")"
            + " from VOUCHER v " 
               ...

2) 使用createNativeQuery方法,将sql映射名称作为第二个参数传递给该方法:

em.createNativeQuery(queryString, "getPoolStateResult");