Hibernate onetomany manytoone 问题

Question

我使用休眠作为 ORM。我有两个实体Shop 和TypeShop。 TypeShop可能有几家店。

@Entity
@Table(name = "shop_types")
public class TypeShop {
    ...
    @OneToMany(fetch = FetchType.EAGER, mappedBy="typeShop", cascade = CascadeType.ALL)
    private Set<Shop> shops;
    ...
}

和

@Entity
@Table(name = "shops")
public class Shop {
    ...
    @ManyToOne(fetch=FetchType.EAGER)
    @JoinColumn(name = "shop_type_id")
    private TypeShop typeShop;
    ...
}

当我想通过 TypeShop id 以 json 格式查找所有 shops 时，我会得到如下信息：

[{"id":146,"name":"First Name","address":"First Address","description":"First Description","coordinates":"59.842055288480076, 29.700164794921875","contacts":"First Contacts","site":"First web site","mail":"First email","photos":[],"typeShop":{"id":11,"name":"Производство газобетона","shops":[{"id":146,"name":"First Name","address":"First Address","description":"First Description","coordinates":"59.842055288480076, 29.700164794921875","contacts":"First Contacts","site":"First web site","mail":"First email","photos":[],"typeShop":{"id":11,"name":"Производство газобетона","shops":[{"id":146,"name":"First Name","address":"First Address","description":"First Description","coordinates":"59.842055288480076, 29.700164794921875","contacts":"First Contacts","site":"First web site","mail":"First email","photos":[],"typeShop":{"id":11,"name":"Производство газобетона","shops":[{"id":146,"name":"First Name","address":"First Address","description":"First Description","coordinates":"59.842055288480076, 29.700164794921875","contacts":"First Contacts","site":"First web site","mail":"First email","photos":[],"typeShop":{"id":11,"name":"Производство газобетона","shops":[{"id":146,"name":"First Name","address":"First Address","description":"First Description","coordinates":"59.842055288480076, 29.700164794921875","contacts":"First Contacts","site":"First web site","mail":"First email","photos":[],"typeShop":{"id":11,"name":"Производство газобетона","shops":[{"id":146,"name":"First Name","address":"First Address","description":"First Description","coordinates":"59.842055288480076, 29.700164794921875","contacts":"First Contacts","site":"First web site","mail":"First email","photos":[],"typeShop":{"id":11,"name":"Производство газобетона","shops":[{"id":146,"name":"First Name","address":"First Address","description":"First Description","coordinates":"59.842055288480076, 29.700164794921875","contacts":"First Contacts","site":"First web site","mail":"First email","photos":[],"typeShop":{"id":11,"name":"Производство газобетона","shops":[{"id":146,"name":"First Name","address":"First Address","description":"First Description","coordinates":"59.842055288480076, 29.700164794921875","contacts":"First Contacts","site":"First web site","mail":"First email","photos":[],"typeShop":{"id":11,"name":"Производство газобетона","shops":[{"id":146,"name":"First Name","address":"First Address","description":"First Description","coordinates":"59.842055288480076, 29.700164794921875","contacts":"First Contacts","site":"First web site","mail":"First email","photos":[],"typeShop":{"id":11,"name":"Производство газобетона","shops":[{"id":146,"name":"First Name","address":"First Address","description":"First Description","coordinates":"59.842055288480076, 29.700164794921875","contacts":"First Contacts","site":"First web site","mail":"First email","photos":[],"typeShop":{"id":11,"name":"Производство газобетона","shops":[{"id":146,"name":"First Name","address":"First Address","description":"First .....

而且这个列表一次又一次地出现。正如您所看到的，由于获取类型 EAGER 我得到了无限的 json 格式。我试图将EAGER 更改为LAZY，但我得到了“failed to lazily initialize a collection of role” exception。

我该如何解决这个问题？提前致谢！

已编辑： 如果我从 Shop 实体中删除 TypeShop 的吸气剂，这会有所帮助。但是我很好奇是否有更好的方法。

Answer 1

这称为 JSON 双向引用问题。参考：http://wiki.fasterxml.com/JacksonFeatureBiDirReferences

检查 @JsonIdentityInfo 和 @JsonBackReference/@JsonManagedReference

用

注释您的实体

@JsonIdentityInfo(generator=ObjectIdGenerators.IntSequenceGenerator.class, property="@id")

应该可以解决你的问题。