我们如何在 JPA/Hibernate 中使用 Integer 或 Long 类型的对象作为外键映射？

Question

I tried below sample code which does not seem to work, while trying to fetch the object from table, hibernate tries to set the User Object on top of Long objects and fails when tried to load the Parent entity which has this createdBy field

any help?

@JoinColumn(name = "CREATED_BY", referencedColumnName = "USER_ID", updatable = false, nullable = false)
@OneToOne(targetEntity = User.class)
private Long createdBy;

I want to use Long/Integer as type of the field and want to make sure its a valid Foreign key to User table which has Primary key USER_ID

Please note that i DO NOT want to use User as type of my object, for example, i do not want below declaration in my class

private User createdBy;

Edit: Reason for such requirement:

Ahh well,.. i'll try to keep it short which is basically one of the problem with ORM's like Hibernate. I have a Super Class AuditLogModel which is extended by each and every entity class in my software (100+ entities), This AuditLogModel class has CreatedBy & ModifiedBy field, If i keep the types of this fields as User, then every entity in my software tries to create a join with user table twice on operations like getResultsList/Merge/refresh. where Merge and Refresh calls on entity manger cannot be controlled by us, its all eager loading in one select query. Since my entities have child entities and they have further childs and so on, this creates more than 61 joins and sometime 100+ joins and causes query performance issues. These createdBy and modified by columns are updated with every insert/update but not required with any query when any entity is loaded, and hence I want to avoid the unneccessari joins here. Hope its understood

Answer 1

Ah OneToOne mapping is used for Entities like this:

@JoinColumn(name = "CREATED_BY", referencedColumnName = "USER_ID", updatable = false, nullable = false)
@OneToOne
private User createdBy;

If you want to use just the database value then you must remove the OneToOne mapping:

@Column(updatable = false, nullable = false)
private Long createdBy;