Question

在Spring Boot应用程序中，我有两个实体Requirement和Product。需求与产品具有一对多关系。

在产品回购接口中，我有一个简单的查询方法，该方法可获取具有给定require_id的产品列表。这是代码：

interface ProductRepo: JpaRepository<Product, Int>{

 fun findProductsByRequirement_Id(id:Int) : List<Product>
}

但是，当从Rest Controller调用此方法时，我可以看到，与每个产品一起，hibernate返回的是对应的需求对象，而不仅仅是request_id。它不止于此，它还返回与JSON结果中的需求对象关联的所有异物（交易和销售）。

我已经在application.properties文件中将此选项设置为“ spring.jpa.properties.hibernate.show_sql = true”，每次调用该查询方法时，我在控制台中都会看到Hibernate不断调用许多复杂的外部联接查询甚至我都没有要求。我认为，当我不需要所有这些异物时，这会消耗不必要的资源。

以下是休眠在后台运行的sql查询：

休眠：将requiremen0_.id选择为id1_8_0_，将requiremen0_.deal_id选择为 deal_id4_8_0_，requiremen0_.requirement_total与requirem2_8_0_， requiremen0_.sale_id为sale_id5_8_0_，requiremen0_.title为 title3_8_0_，deal1_.id为id1_4_1_，deal1_.account_id为 account_7_4_1_，以crm_cust8_4_1_的身分交易1..crm_customer_id， deal1_.exp_closing_date为exp_clos2_4_1_，deal1_.requirement_title为 requirem3_4_1_，deal1_.sales_value为sales_va4_4_1_，deal1_.stage为 stage5_4_1_，deal1_.type为type6_4_1_，deal1_.user_id为 user_id9_4_1_，account2_.id为id1_0_2_，account2_.address为地址2_0_2_，帐户2_.crm_customer_id作为crm_cust9_0_2_， account2_.email为电子邮件3_0_2_，account2_.key_person为 key_pers4_0_2_，account2_.name为name5_0_2_，account2_.phone为电话6_0_2_，帐户2_.status为状态7_0_2_，帐户2_。类型为 type8_0_2_，account2_.user_id为user_id10_0_2_，crmcustome3_.id为 id1_2_3_，crmcustome3_.address作为地址2_2_3_，crmcustome3_.email作为 email3_2_3_，crmcustome3_.key_person作为key_pers4_2_3_， crmcustome3_.name为name5_2_3_，crmcustome3_.number_of_users为 number_o6_2_3_，crmcustome3_.phone作为phone7_2_3_， crmcustome3_.subscription_type作为subscrip8_2_3_， crmcustome3_.validity_exp_date为validity9_2_3_，user4_.id为 id1_11_4_，user4_.crm_customer_id作为crm_cust8_11_4_， user4_.designation为designat2_11_4_，user4_.hierarchy_level为 hierarch3_11_4_，user4_.logged_in作为logging_i4_11_4_，user4_.login_id 作为login_id5_11_4_，user4_.login_pw作为login_pw6_11_4_，user4_.name作为名称7_11_4_，sale5_.id为id1_9_5_，sale5_.crm_customer_id为 crm_cust4_9_5_，sale5_.deal_id作为deal_id5_9_5_，sale5_.sales_date作为 sales_da2_9_5_，sale5_.sales_value作为sales_va3_9_5_，sale5_.user_id 作为user_id6_9_5_，crmcustome6_.id作为id1_2_6_，crmcustome6_.address作为地址2_2_6_，crmcustome6_.email作为电子邮件3_2_6_， crmcustome6_.key_person为key_pers4_2_6_，crmcustome6_.name为 name5_2_6_，crmcustome6_.number_of_users作为number_o6_2_6_， crmcustome6_.phone为phone7_2_6_，crmcustome6_.subscription_type为 subscrip8_2_6_，crmcustome6_.validity_exp_date作为有效期9_2_6_， deal7_.id为id1_4_7_，Deal7_.account_id为account_7_4_7_， deal7_.crm_customer_id为crm_cust8_4_7_，Deal7_.exp_closing_date为 exp_clos2_4_7_，deal7_.requirement_title为requirem3_4_7_， deal7_.sales_value作为sales_va4_4_7_，deal7_.stage作为stage5_4_7_， deal7_.type为type6_4_7_，Deal7_.user_id为user_id9_4_7_，user8_.id 作为id1_11_8_，user8_.crm_customer_id作为crm_cust8_11_8_， user8_.designation为designat2_11_8_，user8_.hierarchy_level为 hierarch3_11_8_，user8_.logged_in作为logging_i4_11_8_，user8_.login_id 作为login_id5_11_8_，user8_.login_pw作为login_pw6_11_8_，user8_.name作为来自需求requirename0_的name7_11_8_左外部加入交易对requiremen0_.deal_id = deal1_.id的Deal1_左外部加入帐户 deal1_.account_id = account2_.id上的account2_左外部联接在deal1_.crm_customer_id = crmcustome3_.id上的crm_customers crmcustome3_ 左外部加入用户user4_ on deal1_.user_id = user4_.id左外部在requiremen0_.sale_id = sale5_.id上左加入外部销售 crm_customers crmcustome6_特价5_.crm_customer_id = crmcustome6_.id 左外加入交易Deal7_待售中5_.deal_id = deal7_.id左外加入用户user8_ on sale5_.user_id = user8_.id，其中requiremen0_.id =？

如何避免这种情况？

以下是产品和需求的实体类：

package com.ksk.crmserver.Model

import com.fasterxml.jackson.annotation.JsonIgnore
import javax.persistence.*

@Entity
@Table(name = "requirements")
data class Requirement(
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        val id: Int = 0,
        @Column(name = "title")
        val title: String = "",

        @OneToMany(mappedBy = "requirement")
        @JsonIgnore
        val products: List<Product>? = null,
        @Column(name = "requirement_total")

        val requirementTotal: Int = 0,

        @ManyToOne
        var deal: Deal? = null,

        @ManyToOne
        val sale: Sale?=null
)


package com.ksk.crmserver.Model

import javax.persistence.*


@Entity
@Table(name = "products", indexes = [Index(name = "idx_product", columnList = "name")])

data class Product(
        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        val id: Int = 0,
        val name: String = "",
        val description: String? = "",

        @Column(name = "unit_cost")
        val unitCost: Double = 0.0,

        @Column(name = "qty")
        val qty: Double? = 0.0,

        val unit: String? = "",

        @Column(name = "total_Cost")
        val totalCost: Double? = 0.0,

        @Column(name = "profit_margin")
        val profitMargin: Double? = 0.0,

        val profit: Double? = 0.0,

        @Column(name = "vat_percentage")
        val vatPercentage: Double? = 0.0,

        val vat: Double? = 0.0,

        @Column(name = "total_price")
        val totalPrice: Double? = 0.0,

        @ManyToOne
        @JoinColumn(name = "requirement_id")
        val requirement: Requirement? = null


)

编辑：我尝试使用EntityManager.getReference来获取Requirement Object的实例。但它仍在运行很长的SQL查询，以便从数据库中按ID提取需求。这是我来自Product的RestController类的代码：

恐怕它仍在运行sql join查询。这是我的Rest Controller代码：

@RestController
@CrossOrigin
class ProductRoute(val productRepo: ProductRepo, val requirementRepo: RequirementRepo) {

    @Autowired
    val entityManager: EntityManager?=null

    @GetMapping("/get/productsByReqId")
    fun getProductsByRequirementId(@RequestParam id: Int): List<Product> {
        val requirement = this.entityManager?.getReference(Requirement::class.java, id) as Requirement
        print("Done fetching the requirement")
        return this.productRepo.findProductsByRequirement(requirement)
    }

这是Hibernate正在运行的sql：

休眠：将requiremen0_.id选择为id1_8_0_，将requiremen0_.deal_id选择为   deal_id4_8_0_，requiremen0_.requirement_total与requirem2_8_0_，   requiremen0_.sale_id为sale_id5_8_0_，requiremen0_.title为   title3_8_0_，deal1_.id为id1_4_1_，deal1_.account_id为   account_7_4_1_，以crm_cust8_4_1_的身分交易1..crm_customer_id，   deal1_.exp_closing_date为exp_clos2_4_1_，deal1_.requirement_title为   requirem3_4_1_，deal1_.sales_value为sales_va4_4_1_，deal1_.stage为   stage5_4_1_，deal1_.type为type6_4_1_，deal1_.user_id为   user_id9_4_1_，account2_.id为id1_0_2_，account2_.address为   地址2_0_2_，帐户2_.crm_customer_id作为crm_cust9_0_2_，   account2_.email为电子邮件3_0_2_，account2_.key_person为   key_pers4_0_2_，account2_.name为name5_0_2_，account2_.phone为   电话6_0_2_，帐户2_.status为状态7_0_2_，帐户2_。类型为   type8_0_2_，account2_.user_id为user_id10_0_2_，crmcustome3_.id为   id1_2_3_，crmcustome3_.address作为地址2_2_3_，crmcustome3_.email作为   email3_2_3_，crmcustome3_.key_person作为key_pers4_2_3_，   crmcustome3_.name为name5_2_3_，crmcustome3_.number_of_users为   number_o6_2_3_，crmcustome3_.phone作为phone7_2_3_，   crmcustome3_.subscription_type作为subscrip8_2_3_，   crmcustome3_.validity_exp_date为validity9_2_3_，user4_.id为   id1_11_4_，user4_.crm_customer_id作为crm_cust8_11_4_，   user4_.designation为designat2_11_4_，user4_.hierarchy_level为   hierarch3_11_4_，user4_.logged_in作为logging_i4_11_4_，user4_.login_id   作为login_id5_11_4_，user4_.login_pw作为login_pw6_11_4_，user4_.name作为   名称7_11_4_，产品5_.requirement_id为require13_5_5_，   products5_.id为id1_5_5_，product5_.id为id1_5_6_，   product5_.description为descript2_5_6_，products5_.name为   名称3_5_6_，产品5_。利润为利润4_5_6_，   products5_.profit_margin为profit_m5_5_6_，product5_.qty为   qty6_5_6_，products5_.requirement_id为require13_5_6_，   product5_.total_price为total_co7_5_6_，product5_.total_price为   total_pr8_5_6_，products5_.unit为unit9_5_6_，products5_.unit_cost为   unit_co10_5_6_，products5_.vat如vat11_5_6_，   products5_.vat_percentage为vat_per12_5_6_，sale6_.id为id1_9_7_，   sale6_.crm_customer_id为crm_cust4_9_7_，sale6_.deal_id为   deal_id5_9_7_，sale6_.sales_date作为sales_da2_9_7_，sale6_.sales_value   作为sales_va3_9_7_，sale6_.user_id作为user_id6_9_7_，crmcustome7_.id作为   id1_2_8_，crmcustome7_.address作为地址2_2_8_，crmcustome7_.email作为   email3_2_8_，crmcustome7_.key_person作为key_pers4_2_8_，   crmcustome7_.name为name5_2_8_，crmcustome7_.number_of_users为   number_o6_2_8_，crmcustome7_.phone如phone7_2_8_，   crmcustome7_.subscription_type作为subscrip8_2_8_，   crmcustome7_.validity_exp_date为validity9_2_8_，deal8_.id为   id1_4_9_，deal8_.account_id作为account_7_4_9_，deal8_.crm_customer_id   作为crm_cust8_4_9_，deal8_.exp_closing_date作为exp_clos2_4_9_，   deal8_.requirement_title为requirem3_4_9_，Deal8_.sales_value为   sales_va4_4_9_，deal8_.stage为stage5_4_9_，deal8_.type为   type6_4_9_，deal8_.user_id作为user_id9_4_9_，user9_.id作为id1_11_10_，   user9_.crm_customer_id为crm_cust8_11_10_，user9_.designation为   designat2_11_10_，user9_.hierarchy_level作为hierarch3_11_10_，   user9_.logged_in为logging_i4_11_10_，user9_.login_id为   login_id5_11_10_，user9_.login_pw为login_pw6_11_10_，user9_.name为   需求需求中的name7_11_10_来自左外部加入交易   对requiremen0_.deal_id = deal1_.id的Deal1_左外部加入帐户   deal1_.account_id = account2_.id上的account2_左外部联接   在deal1_.crm_customer_id = crmcustome3_.id上的crm_customers crmcustome3_   左外部加入用户user4_ on deal1_.user_id = user4_.id左外部   在requiremen0_.id = products5_.requirement_id上加入产品products5_   左外部加入sales sale6_ on requiremen0_.sale_id = sale6_.id   外连接crm_customers crmcustome7_上   sale6_.crm_customer_id = crmcustome7_.id左外加入交易Deal8_   sale6_.deal_id = deal8_.id向左外部加入用户user9_   sale6_.user_id = user9_.id其中requiremen0_.id =？

完成获取要求2019-02-16 21：01：00.341 INFO 80558-   [nio-8080-exec-1] o.h.h.i.QueryTranslatorFactoryInitiator：   HHH000397：使用ASTQueryTranslatorFactory

休眠：选择product0_.id作为id1_5_，选择product0_.description作为   descript2_5_，product0_.name为name3_5_，product0_.profit为   Profit4_5_，product0_.profit_margin为profit_m5_5_，product0_.qty为   qty6_5_，product0_.requirement_id为require13_5_，   product0_.total_cost为total_co7_5_，product0_.total_price为   total_pr8_5_，product0_.unit为unit9_5_，product0_.unit_cost为   unit_co10_5_，product0_.vat为vat11_5_，product0_.vat_percentage为   来自产品product0_的vat_per12_5_，其中product0_.requirement_id =？

Answer 1

您可以将ManyToOne关系的fetchType设置为Lazy（ManyToOne关系的默认值为Eager）。这样，Hibernate仅在调用被调用对象时才加载它们。如果要让Hibernate返回Id而不是整个引用的对象，则可以在此处查找：Hibernate - Foreign keys instead of Entities

Spring Boot：HIbernate不断调用复杂的外部联接查询

1 个答案: