Spring boot OneToOne关系问题

我需要从数据库中获取数据，但不包含某些字段，但我接收或删除了所有数据（带有关系）或错误

import org.springframework.data.domain.Persistable
import org.springframework.data.util.ProxyUtils
import java.io.Serializable
import javax.persistence.GeneratedValue
import javax.persistence.Id
import javax.persistence.MappedSuperclass
import javax.persistence.Transient

@MappedSuperclass
abstract class AbstractEntity<T : Serializable>() : Persistable<T> {

    companion object {
        private val serialVersionUID = -5554308939380869754L
    }

    @Id
    @GeneratedValue
    private var id: T? = null

    override fun getId(): T? {
        return id
    }

    fun setId(id:T){
        this.id = id
    }

    /**
     * Must be [Transient] in order to ensure that no JPA provider complains because of a missing setter.
     *
     * @see org.springframework.data.domain.Persistable.isNew
     */
    @Transient
    override fun isNew() = null == getId()

    override fun toString() = "Entity of type ${this.javaClass.name} with id: $id"

    override fun equals(other: Any?): Boolean {
        other ?: return false

        if (this === other) return true

        if (javaClass != ProxyUtils.getUserClass(other)) return false

        other as AbstractEntity<*>

        return if (null == this.getId()) false else this.getId() == other.getId()
    }

    override fun hashCode(): Int {
        return 31
    }
}

我知道这是通过@OneToOne发生的，但我无法寻求解决方案；(

我只需要接收一些字段，如：产品名称、描述、产品模型、产品文章、产品计数

---

谢谢你们的帮助，伙计们！

@OneToOne

如果您允许

null

值，这将是一个棘手的问题

JPA必须尝试访问另一个表中的记录，即使该属性是用延迟初始化签名的，因为它必须决定是将该属性设置为

null

还是代理对象

它无法自动将其设置为

null

，因为可能存在关联的对象。 它也无法自动创建代理对象，因为表中没有为该属性的id指定的列（因为默认情况下，一对一关系由共享PK映射）

因此，确定关联实体是否存在的唯一方法是尝试从其自己的表中加载其

id

。如果此查询返回

null

，则没有关联实体，否则JPA可以从此id创建代理对象

如果确实需要避免此额外请求，请将

product\u category\u属性

表的外键添加到

product

表中

@OneToOne(cascade = [CascadeType.PERSIST, CascadeType.MERGE], orphanRemoval = false, fetch = FetchType.LAZY)
@JoinColumn(name='product_category_property')
var productCategoryProperty: ProductCategoryPropertyEntity = ProductCategoryPropertyEntity()

你可以找到进一步的解释

import ua.jdroidcoder.jdcshop.dto.ProductCategoryPropertyDto
import javax.persistence.*

@Entity
@Table(name = "product_category_property")
class ProductCategoryPropertyEntity : AbstractEntity<Long> {

    @OneToMany(cascade = [CascadeType.PERSIST, CascadeType.MERGE], orphanRemoval = false)
    var simpleProperties: MutableList<ProductPropertySimpleEntity> = ArrayList()

    @OneToMany(cascade = [CascadeType.PERSIST, CascadeType.MERGE], orphanRemoval = false)
    var advancedProperties: MutableList<ProductPropertySimpleEntity> = ArrayList()

    constructor() : super() {
    }

    fun convertToDto(): ProductCategoryPropertyDto {
        val simple = ProductCategoryPropertyDto()
        simple.id = id
        simpleProperties?.forEach {
            simple.simpleProperties.add(it.convertToDto())
        }
        advancedProperties?.forEach {
            simple.advancedProperties.add(it.convertToDto())
        }
        return simple
    }
}

import ua.jdroidcoder.jdcshop.dto.PropertySimpleDto
import javax.persistence.Column
import javax.persistence.Entity
import javax.persistence.Table

@Entity
@Table(name = "product_property_simple")
class ProductPropertySimpleEntity : AbstractEntity<Long> {
    @Column(name = "property_name")
    var propertyName: String = ""

    @Column(name = "property_value")
    var propertyValue: String = ""

    @Column(name = "parent_id")
    var parentId: Long? = null

    @Column(name = "parent_id_in_category")
    var parentIdInCategory: Long? = null

    @Column(name = "id_in_category")
    var idInCategory: Long? = null

    constructor() : super() {
    }

    fun convertToDto(): PropertySimpleDto {
       return PropertySimpleDto(id!!,propertyName,parentId,propertyValue)
    }
}

Hibernate: select productent0_.id as id1_3_, productent0_.category_id as categor13_3_, productent0_.description as descript2_3_, productent0_.images as images3_3_, productent0_.is_available as is_avail4_3_, productent0_.keywords as keywords5_3_, productent0_.product_articul as product_6_3_, productent0_.product_category_property_id as product14_3_, productent0_.product_count as product_7_3_, productent0_.product_extra as product_8_3_, productent0_.product_model as product_9_3_, productent0_.product_name as product10_3_, productent0_.product_price as product11_3_, productent0_.product_total_price as product12_3_ from product productent0_
Hibernate: select categoryen0_.id as id1_0_0_, categoryen0_.category_name as category2_0_0_, categoryen0_.prom_category_id as prom_cat3_0_0_ from category categoryen0_ where categoryen0_.id=?
Hibernate: select productcat0_.id as id1_4_0_ from product_category_property productcat0_ where productcat0_.id=?
Hibernate: select simpleprop0_.product_category_property_entity_id as product_1_6_0_, simpleprop0_.simple_properties_id as simple_p2_6_0_, productpro1_.id as id1_7_1_, productpro1_.id_in_category as id_in_ca2_7_1_, productpro1_.parent_id as parent_i3_7_1_, productpro1_.parent_id_in_category as parent_i4_7_1_, productpro1_.property_name as property5_7_1_, productpro1_.property_value as property6_7_1_ from product_category_property_simple_properties simpleprop0_ inner join product_property_simple productpro1_ on simpleprop0_.simple_properties_id=productpro1_.id where simpleprop0_.product_category_property_entity_id=?
Hibernate: select advancedpr0_.product_category_property_entity_id as product_1_5_0_, advancedpr0_.advanced_properties_id as advanced2_5_0_, productpro1_.id as id1_7_1_, productpro1_.id_in_category as id_in_ca2_7_1_, productpro1_.parent_id as parent_i3_7_1_, productpro1_.parent_id_in_category as parent_i4_7_1_, productpro1_.property_name as property5_7_1_, productpro1_.property_value as property6_7_1_ from product_category_property_advanced_properties advancedpr0_ inner join product_property_simple productpro1_ on advancedpr0_.advanced_properties_id=productpro1_.id where advancedpr0_.product_category_property_entity_id=?

@OneToOne(cascade = [CascadeType.PERSIST, CascadeType.MERGE], orphanRemoval = false, fetch = FetchType.LAZY)
@JoinColumn(name='product_category_property')
var productCategoryProperty: ProductCategoryPropertyEntity = ProductCategoryPropertyEntity()