我有ParentRepository为ParentEntity ies。Child1Entity和Child2Entity继承自ParentEntity。Child1Entity与OutputFileEntity之间存在@OneToOne惰性关联。
ParentEntity只有id字段。
是否可以以某种方式获取outputFile？我需要存储库返回ParentEntity类型，我需要保持与OutputFileEntity的惰性关联
堆栈：Kotlin，MySQL，Hibernate，Postgres
它在@Test中的H2上运行良好，但在Postresql上我有错误

@Repository
interface ParentRepository : CrudRepository<ParentEntity, Long> {

    @Query(
        """
        SELECT DISTINCT p FROM ParentEntity p 
        LEFT JOIN Child1Entity ch1 ON p.id = ch1.id
        LEFT JOIN Child2Entity ch2 ON p.id = ch2.id
        LEFT JOIN ch1.outputFile outputFile
        """
    )
    fun getParents(pageable: Pageable): Page<ParentEntity>
}

错误是只在Postresql当尝试访问outputFile：

org.hibernate.LazyInitializationException: could not initialize proxy [xxxxxx.OutputFileEntity#302] - no Session

更多信息

@Entity
@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
@SequenceGenerator(name = ParentEntity.GENERATOR_NAME, sequenceName = ParentEntity.SEQUENCE_NAME, allocationSize = 1)
abstract class ParentEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = GENERATOR_NAME)
    var id: Long = 0

    // static fields
    companion object {
        const val SEQUENCE_NAME = "generic_parent_id_seq"
        const val GENERATOR_NAME = "${SEQUENCE_NAME}_gen"
    }
}

@Entity
@Table(name = TABLE_NAME)
class Child1Entity(

    val abc1: String? = null,

    @OneToOne(
        cascade = [CascadeType.ALL],
        fetch = FetchType.LAZY,
        orphanRemoval = true
    )
    val outputFile: OutputFileEntity,

    ) : ParentEntity() {

    // static fields
    companion object {
        const val TABLE_NAME = "child1"
    }
}

@Entity
@Table(name = TABLE_NAME)
class Child2Entity(

    val abc2: String? = null,

    ) : ParentEntity() {

    // static fields
    companion object {
        const val TABLE_NAME = "child2"
    }
}

当我将FETCH添加到存储库时：

SELECT DISTINCT p FROM ParentEntity p 
        LEFT JOIN Child1Entity ch1 ON p.id = ch1.id
        LEFT JOIN Child2Entity ch2 ON p.id = ch2.id
        LEFT JOIN FETCH ch1.outputFile outputFile

我得到了这个错误

org.hibernate.QueryException: query specified join fetching, but the owner of the fetched association was not present in the select list [FromElement{explicit,not a collection join,fetch join,fetch non-lazy properties,classAlias=outputFile,role=xxxxx.Child1Entity.outputFile,tableName=output_file,tableAlias=outputfile3_,origin=child1,columns={child1_.output_file_id,className=xxxx.OutputFileEntity}}]
    at org.hibernate.hql.internal.ast.tree.SelectClause.initializeExplicitSelectClause(SelectClause.java:230)
    at org.hibernate.hql.internal.ast.HqlSqlWalker.useSelectClause(HqlSqlWalker.java:1039)
    at org.hibernate.hql.internal.ast.HqlSqlWalker.processQuery(HqlSqlWalker.java:807)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:703)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:339)
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:287)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:276)
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:192)

所以我尝试添加子实体选择列表

SELECT  p, ch1, ch2 FROM ParentEntity p 
        LEFT JOIN Child1Entity ch1 ON p.id = ch1.id
        LEFT JOIN Child2Entity ch2 ON p.id = ch2.id
        LEFT JOIN FETCH ch1.outputFile outputFile

但得到

.IllegalArgumentException: Cannot create TypedQuery for query with more than one return using requested result type [xxxxx.ParentEntity]
    at org.hibernate.internal.AbstractSharedSessionContract.resultClassChecking(AbstractSharedSessionContract.java:894)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:849)
    at org.hibernate.internal.AbstractSharedSessionContract.createQuery(AbstractSharedSessionContract.java:114)