引起原因:org.hibernate.QueryException:无法取消引用标量集合元素:角色 [英] getting Caused by: org.hibernate.QueryException: cannot dereference scalar collection element: roles

问题描述

我有这个课程，我正试图从用户表中访问 mobileNumbers 和 roles ，但是我习惯了 lazy 出现'惰性初始化错误.

I have this class , and i'am trying to acess mobileNumbers and roles from the user table , but being lazy intialized i keep getting 'lazy intialization error.

我不希望删除 LAZY 提取，因为很少需要完全访问该对象，但这是必需的.因此，为了克服这一点，我尝试添加 @Transactional ，但在本文中 https://codete.com/blog/5-common-spring-transactional-pitfalls/在我看来，这是一个不好的选择，我尝试使用 join fetch ，但它一直提供 multiplebagfetchexception ，因此我试图一次一次获取它们(我的意思是Element Collections)

I do not wan't to remove the LAZY fetch as complete access of the object is rarely required , but is required. So to overcome it first i tried to add @Transactional but going by this article https://codete.com/blog/5-common-spring-transactional-pitfalls/ it seems a bad approch in my case, i tried using join fetch but it keeps giving multiplebagfetchexception ,hence i tried to fetch them one at a time ( Element Collections i mean)

使用此存储库类

public interface UserRespository extends JpaRepository<UserDao, Long> {

    Optional<UserDao> getByUserNameIgnoreCase(String userName);
//    Optional<UserDao> findByUserNameIgnoreCase(String userName);

    @Query(value = "select dao.roles.roles from UserDao dao inner join dao.roles r on dao.userName in elements(r.userName) and upper(dao.userName) = upper(?1)")
    Object getByUserNameIgnoreCaseComplete2(String userName);
}

然后我得到了他的错误

Caused by: org.hibernate.QueryException: cannot dereference scalar collection element: roles
    at org.hibernate.persister.collection.ElementPropertyMapping.toType(ElementPropertyMapping.java:33) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.persister.collection.AbstractCollectionPersister.toType(AbstractCollectionPersister.java:1644) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.tree.FromElementType.getPropertyType(FromElementType.java:396) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.tree.FromElement.getPropertyType(FromElement.java:515) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.tree.DotNode.getDataType(DotNode.java:682) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.tree.DotNode.prepareLhs(DotNode.java:265) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.tree.DotNode.resolve(DotNode.java:205) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:114) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:109) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.tree.FromReferenceNode.resolve(FromReferenceNode.java:104) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.tree.DotNode.resolveSelectExpression(DotNode.java:744) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.HqlSqlWalker.resolveSelectExpression(HqlSqlWalker.java:1057) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExpr(HqlSqlBaseWalker.java:2295) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectExprList(HqlSqlBaseWalker.java:2232) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectClause(HqlSqlBaseWalker.java:1503) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.query(HqlSqlBaseWalker.java:585) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.selectStatement(HqlSqlBaseWalker.java:313) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.antlr.HqlSqlBaseWalker.statement(HqlSqlBaseWalker.java:261) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.analyze(QueryTranslatorImpl.java:271) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    at org.hibernate.hql.internal.ast.QueryTranslatorImpl.doCompile(QueryTranslatorImpl.java:191) ~[hibernate-core-5.3.9.Final.jar:5.3.9.Final]
    ... 112 common frames omitted

我不确定为什么会一直出现此错误.还有其他方法可以获取整个对象吗?

I'm not sure why i keep getting this error.Is there any other way i can get the entire object??

请帮助.

实际班级

@Entity
@Table(name = "users")
@Data
@NoArgsConstructor
public class UserDao implements Serializable {

    @Id
    @GeneratedValue
    private long id;

    @Column(name = "user_name", nullable = false, unique = true)
    private String userName;

    @Column(name = "password", nullable = false)
    private String password;

    @ElementCollection(targetClass = java.lang.String.class)
    @CollectionTable(name = "mobile_numbers_List",joinColumns = @JoinColumn(name = "user_name",referencedColumnName = "user_name"))
    @Column(name = "mobile_number")
    private List<String> mobileNumbers;

    @ElementCollection(targetClass = java.lang.String.class)
    @CollectionTable(name = "roles_list",joinColumns = @JoinColumn(name = "user_name",referencedColumnName = "user_name"))
    @Column(name = "roles")
    private List<String> roles;
}

推荐答案

您

This seems like a similar question you previous questio , and the answer to the previous one and this one is same.

您的查询在这里错误

    @Query(value = "select dao.roles.roles from UserDao dao inner join dao.roles r on dao.userName in elements(r.userName) and upper(dao.userName) = upper(?1)")
    Object getByUserNameIgnoreCaseComplete2(String userName);

它正在尝试获取 dao.roles.roles ，如果它甚至不存在.

it's trying to fetch dao.roles.roles which if does not even exist.

这是您应该尝试的一些更改

here are some changes you should try

1. 将 dao.roles.roles 更改为r(因为您已经创建了别名，让我们使用它)
2. 删除元素(r.userName)中的 dao.userName 不是必需的，spring会自动执行此操作，甚至无需指定它.
3. 将返回类型更改为list，它是 ElementCollection ，即元素的 Collection

1. change dao.roles.roles to r (as you already created an alias , let's use it)
2. remove dao.userName in elements(r.userName) it's not required, spring does this automatically without even specifying it.
3. change the return type to list , it's ElementCollection i.e Collection of elements

这是您最终查询的样子

    @Query(value = "select r from UserDao dao inner join dao.roles r on upper(dao.userName) = upper(?1)")
    List<String> getByUserNameIgnoreCaseComplete2(String userName);

这篇关于引起原因:org.hibernate.QueryException:无法取消引用标量集合元素:角色的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！