Problems with inserting data using springdata jpa - Codes Helper

I am using springboot2.1.2 to develop a project. I have a problem saving objects with repository. Here are my two entity classes:

@Entity
@Getter
@Setter
@NoArgsConstructor
public class User {

    @Id
    private String email;
    private String userName, password;

    @OneToMany(targetEntity = Address.class
            , fetch = FetchType.EAGER, mappedBy = "user"
            , cascade = {CascadeType.PERSIST})
    private List<Address> addressList = new ArrayList<>();

    public User(String email, String userName, String password) {
        this.email = email;
        this.userName = userName;
        this.password = password;
    }

    public void addAddress(Address address) {
        addressList.add(address);
    }

}


@Entity
@Getter
@Setter
@NoArgsConstructor
public class Address {
    @Id
    private long id;
    private String name, phone, location;
    @ManyToOne(targetEntity = User.class)
    private User user;

    public Address(String name, String phone, String location, User user) {
        this.name = name;
        this.phone = phone;
        this.location = location;
        this.user = user;
    }
}

the following is the test code:

@Test
public void test1() {
    User user = new User("email", "userName", "password");
    Address address1 = new Address("name1", "phone1", "loc1", user);
    Address address2 = new Address("name2", "phone2", "loc2", user);
    user.addAddress(address1);
    user.addAddress(address2);
    userRepository.saveAndFlush(user);

    List<Address> addressList = addressRepository.findAllByUser(user);
    addressList.stream().forEach(x -> System.out.println(x.getName()));
}

it"s easy to see that there is an one-to-many relationship between the User class and the Address class, and I also set up cascading saving, but when I run the test method, I get the following error:

org.springframework.orm.jpa.JpaObjectRetrievalFailureException: Unable to find ycqian.yummy.entity.Address with id 0; nested exception is javax.persistence.EntityNotFoundException: Unable to find ycqian.yummy.entity.Address with id 0

at org.springframework.orm.jpa.EntityManagerFactoryUtils.convertJpaAccessExceptionIfPossible(EntityManagerFactoryUtils.java:378)
at org.springframework.orm.jpa.vendor.HibernateJpaDialect.translateExceptionIfPossible(HibernateJpaDialect.java:255)
at org.springframework.orm.jpa.AbstractEntityManagerFactoryBean.translateExceptionIfPossible(AbstractEntityManagerFactoryBean.java:527)
at org.springframework.dao.support.ChainedPersistenceExceptionTranslator.translateExceptionIfPossible(ChainedPersistenceExceptionTranslator.java:61)
at org.springframework.dao.support.DataAccessUtils.translateIfNecessary(DataAccessUtils.java:242)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:153)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.data.jpa.repository.support.CrudMethodMetadataPostProcessor$CrudMethodMetadataPopulatingMethodInterceptor.invoke(CrudMethodMetadataPostProcessor.java:135)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.interceptor.ExposeInvocationInterceptor.invoke(ExposeInvocationInterceptor.java:93)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.data.repository.core.support.SurroundingTransactionDetectorMethodInterceptor.invoke(SurroundingTransactionDetectorMethodInterceptor.java:61)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.aop.framework.JdkDynamicAopProxy.invoke(JdkDynamicAopProxy.java:212)
at com.sun.proxy.$Proxy91.saveAndFlush(Unknown Source)
at ycqian.yummy.repository.UserRepositoryTest.test1(UserRepositoryTest.java:31)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
at org.springframework.test.context.junit4.statements.RunBeforeTestExecutionCallbacks.evaluate(RunBeforeTestExecutionCallbacks.java:74)
at org.springframework.test.context.junit4.statements.RunAfterTestExecutionCallbacks.evaluate(RunAfterTestExecutionCallbacks.java:84)
at org.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:251)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:97)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:190)
at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

Caused by: javax.persistence.EntityNotFoundException: Unable to find ycqian.yummy.entity.Address with id 0
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl$JpaEntityNotFoundDelegate.handleEntityNotFound(EntityManagerFactoryBuilderImpl.java:162)
at org.hibernate.event.internal.DefaultLoadEventListener.load(DefaultLoadEventListener.java:230)
at org.hibernate.event.internal.DefaultLoadEventListener.proxyOrLoad(DefaultLoadEventListener.java:281)
at org.hibernate.event.internal.DefaultLoadEventListener.doOnLoad(DefaultLoadEventListener.java:124)
at org.hibernate.event.internal.DefaultLoadEventListener.onLoad(DefaultLoadEventListener.java:92)
at org.hibernate.internal.SessionImpl.fireLoad(SessionImpl.java:1257)
at org.hibernate.internal.SessionImpl.internalLoad(SessionImpl.java:1140)
at org.hibernate.type.EntityType.resolveIdentifier(EntityType.java:682)
at org.hibernate.type.EntityType.resolve(EntityType.java:464)
at org.hibernate.type.ManyToOneType.resolve(ManyToOneType.java:239)
at org.hibernate.type.EntityType.resolve(EntityType.java:457)
at org.hibernate.type.EntityType.replace(EntityType.java:358)
at org.hibernate.type.CollectionType.replaceElements(CollectionType.java:551)
at org.hibernate.type.CollectionType.replace(CollectionType.java:699)
at org.hibernate.type.TypeHelper.replace(TypeHelper.java:163)
at org.hibernate.event.internal.DefaultMergeEventListener.copyValues(DefaultMergeEventListener.java:393)
at org.hibernate.event.internal.DefaultMergeEventListener.entityIsDetached(DefaultMergeEventListener.java:327)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:170)
at org.hibernate.event.internal.DefaultMergeEventListener.onMerge(DefaultMergeEventListener.java:69)
at org.hibernate.internal.SessionImpl.fireMerge(SessionImpl.java:901)
at org.hibernate.internal.SessionImpl.merge(SessionImpl.java:887)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.orm.jpa.SharedEntityManagerCreator$SharedEntityManagerInvocationHandler.invoke(SharedEntityManagerCreator.java:308)
at com.sun.proxy.$Proxy88.merge(Unknown Source)
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.save(SimpleJpaRepository.java:492)
at org.springframework.data.jpa.repository.support.SimpleJpaRepository.saveAndFlush(SimpleJpaRepository.java:503)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.springframework.data.repository.core.support.RepositoryComposition$RepositoryFragments.invoke(RepositoryComposition.java:359)
at org.springframework.data.repository.core.support.RepositoryComposition.invoke(RepositoryComposition.java:200)
at org.springframework.data.repository.core.support.RepositoryFactorySupport$ImplementationMethodExecutionInterceptor.invoke(RepositoryFactorySupport.java:644)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.doInvoke(RepositoryFactorySupport.java:608)
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.lambda$invoke$3(RepositoryFactorySupport.java:595)
at org.springframework.data.repository.core.support.RepositoryFactorySupport$QueryExecutorMethodInterceptor.invoke(RepositoryFactorySupport.java:595)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.data.projection.DefaultMethodInvokingMethodInterceptor.invoke(DefaultMethodInvokingMethodInterceptor.java:59)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:294)
at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
at org.springframework.dao.support.PersistenceExceptionTranslationInterceptor.invoke(PersistenceExceptionTranslationInterceptor.java:139)
... 40 more

it"s strange that I obviously want to save the object, but the error tells me that I can"t find the object. I output the sql statement and find that springdata jpa generates the following sql:

Hibernate: select user0_.email as email1_1_0_, user0_.password as password2_1_0_, user0_.user_name as user_nam3_1_0_ from user user0_ where user0_.email=?
Hibernate: select addresslis0_.user_email as user_ema5_0_0_, addresslis0_.id as id1_0_0_, addresslis0_.id as id1_0_1_, addresslis0_.location as location2_0_1_, addresslis0_.name as name3_0_1_, addresslis0_.phone as phone4_0_1_, addresslis0_.user_email as user_ema5_0_1_ from address addresslis0_ where addresslis0_.user_email=?
Hibernate: select address0_.id as id1_0_0_, address0_.location as location2_0_0_, address0_.name as name3_0_0_, address0_.phone as phone4_0_0_, address0_.user_email as user_ema5_0_0_, user1_.email as email1_1_1_, user1_.password as password2_1_1_, user1_.user_name as user_nam3_1_1_ from address address0_ left outer join user user1_ on address0_.user_email=user1_.email where address0_.id=?

you can see that the select statement was executed before insert, which is the cause of the error in the test code, but I don"t know why these sql statements are generated before insert. Can anyone help me?