spring-data-jpa - 出现错误无法在类上找到适当的构造函数

Question

我正在尝试将 native SQL 结果映射到我的 POJO。这是配置。我正在使用 Spring 。

<bean id="ls360Emf" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean" >
    <property name="dataSource" ref="ls360DataSource" />
    <property name="jpaVendorAdapter" ref="vendorAdaptor" />         
    <property name="packagesToScan" value="abc.xyz"/>
    <property name="jpaProperties">
        <props>
            <prop key="hibernate.dialect">org.hibernate.dialect.SQLServerDialect</prop>
            <prop key="hibernate.max_fetch_depth">3</prop>
            <prop key="hibernate.jdbc.fetch_size">50</prop>
            <prop key="hibernate.jdbc.batch_size">10</prop>
            <prop key="hibernate.show_sql">true</prop>              
        </props>        
    </property>
</bean> 

这是我的类(class)

@SqlResultSetMapping(
    name="courseCompletionMapping", 
    classes = {
        @ConstructorResult(targetClass = CourseCompletion.class,
            columns={
                @ColumnResult(name = "StoreId", type = String.class),
                @ColumnResult(name = "ProductId", type = String.class),
                @ColumnResult(name = "UserName", type = String.class),
                @ColumnResult(name = "Score", type = Integer.class),
                @ColumnResult(name = "CompletionDate", type = Date.class)
             }
        )
    }
) 
@Entity
public class CourseCompletion {
    private String storeId;

    @Id
    private String productId;
    private String userName;
    private int score;
    private Date completionDate;

    public CourseCompletion() {
    }

    public CourseCompletion(String storeId, String productId, String userName, int score, Date completionDate) {
        this.storeId = storeId;
        this.productId = productId;
        this.userName = userName;
        this.score = score;
        this.completionDate = completionDate;
    }

    // getters and setters

这是我的称呼

    Properties coursePropertiesFile = SpringUtil.loadPropertiesFileFromClassPath("course.properties");
    String queryString = coursePropertiesFile.getProperty("course.completion.sql");

    long distributorId = 1;
    String fromDate = "2009-09-22 00:00:00";
    String toDate = "2014-04-11 23:59:59";

     Query query = em.createNativeQuery(queryString, "courseCompletionMapping");

     //Query query = em.createNamedQuery("findAllEmployeeDetails");
     query.setParameter("distributorId", distributorId);
     query.setParameter("fromDate", fromDate);
     query.setParameter("toDate", toDate);

     @SuppressWarnings("unchecked")
     List<CourseCompletion> courseCompletionList = query.getResultList();

但是说到线路

List<CourseCompletion> courseCompletionList = query.getResultList();

我收到一个错误

Could not locate appropriate constructor on class : mypackage.CourseCompletion

这是我正在尝试的查询

select d.DISTRIBUTORCODE AS StoreId, u.USERGUID AS ProductId, u.UserName,
    lcs.HIGHESTPOSTTESTSCORE AS Score, lcs.CompletionDate 
from VU360User u 
inner join learner l on u.ID = l.VU360USER_ID 
inner join LEARNERENROLLMENT le on le.LEARNER_ID = l.ID 
inner join LEARNERCOURSESTATISTICS lcs on lcs.LEARNERENROLLMENT_ID = le.ID 
inner join customer c on c.ID = l.CUSTOMER_ID 
inner join DISTRIBUTOR d on d.ID = c.DISTRIBUTOR_ID 
where d.ID = :distributorId 
and lcs.COMPLETIONDATE is not null 
and (lcs.COMPLETIONDATE between :fromDate and :toDate) 
and lcs.COMPLETED = 1

为什么我会收到此错误？

谢谢

Answer 1

发生此异常是因为 JPA 不会更改从数据库返回的 native 查询的列类型。因此，您的类型不匹配。我不确定在您的情况下哪一列导致此问题(这取决于您使用的 DBMS)，但我怀疑您有 BigInteger在结果集中而不是 Integer对于分数列。为了 100% 确定，请将断点添加到 ConstructorResultColumnProcessor.resolveConstructor(Class targetClass, List<Type> types)并进行调查。发现不匹配后，更改映射类中的字段类型。

另一个解决方案是不使用 @SqlResultSetMapping根本不。作为您的CourseCompletion类是一个托管实体，您应该能够将 native 查询直接映射到它。请参阅this question了解更多信息。