java - Hibernate/H2 @OneToMany "Referential integrity constraint violation"删除子项？

Question

你好，我有一个相当简单的关系。一名患者可以进行多次测量。我使用了 H2 文件数据库和 Hibernate。

问题:当我尝试删除患者的测量结果时，出现以下错误。

Referential integrity constraint violation: "FK_O423U89KR6K78NNG1PO0ISDF6: PUBLIC.PATIENTVO_MEASUREMENTVO FOREIGN KEY(MEASUREMENTS_ID) REFERENCES PUBLIC.MEASUREMENTVO(ID) (X'3c2b9ee868f645c5a5a743c2a409ab5e')"; SQL statement:
delete from MeasurementVO where id=? [23503-185]

关系中的患者部分:

@OneToMany(orphanRemoval=true, cascade={CascadeType.PERSIST, CascadeType.REMOVE, CascadeType.MERGE}, mappedBy = "patient", fetch = FetchType.EAGER)
public List<MeasurementVO> getMeasurements() {
    return measurements;
}

关系的测量部分:

@ManyToOne
@JoinColumn
public PatientVO getPatient() {
    return patient.get();
}

应删除测量的函数:

@Override
@Transactional
public boolean removeMeasurementFromPatient(PatientVO patientVO, MeasurementVO measurementVO) {
        EntityManager manager = emProvider.get();
        PatientVO patientAlreadyInDB = manager.find(PatientVO.class, patientVO.getPatientId());

        if (patientAlreadyInDB != null) {
            patientAlreadyInDB.getMeasurements().removeIf(measurement -> measurement.getId().equals(measurementVO.getId()));
            manager.merge(patientAlreadyInDB);
            return true;
        } else {
            return false;
        }
    }

以及持久性 XML:

<?xml version="1.0" encoding="UTF-8" ?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence"
             xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
             xsi:schemaLocation="http://java.sun.com/xml/ns/persistence
 http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd" version="1.0">

    <persistence-unit name="db" transaction-type="RESOURCE_LOCAL">
        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>

        <class>ch.fhnw.ima.doggait.vo.PatientVO</class>
        <class>ch.fhnw.ima.doggait.vo.MeasurementVO</class>
        <class>ch.fhnw.ima.doggait.vo.MeasurementAttributesVO</class>
        <class>ch.fhnw.ima.doggait.vo.TimeMark</class>

        <properties>
            <property name="connection.driver_class" value="org.h2.Driver"/>
           <!-- <property name="hibernate.connection.url" value="jdbc:h2:mem:db"/>-->
            <property name="hibernate.connection.url" value="jdbc:h2:file:./database/dogdatabase"/>
            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
            <!--<property name="hibernate.hbm2ddl.auto" value="create-drop"/>-->
            <property name="hibernate.hbm2ddl.auto" value="update"/>
            <property name="hibernate.show_sql" value="true"/>
        </properties>
    </persistence-unit>
</persistence>

是否有人提示我为什么无法从患者身上删除测量结果，然后继续保留他/她？

Answer 1

从违反约束的表的名称(PATIENTVO_MEASUREMENTVO)来看，您似乎有一个中间表来实现该关系。这通常用于多对多关系。

作为一对多关系，为什么不直接将测量中的外键添加到患者？