Warm tip: This article is reproduced from stackoverflow.com, please click
database hibernate java jpa mapping

Map one entity to different columns of one table using Hibernate

发布于 2020-03-27 10:21:35

I have a simple bank app, which have Account and Transaction entity. One account keep withdraw and deposit transaction (they can be between two accounts or account&ATM(it will be null in the corresponding field). I use @ManyToOne and @OneToMany annotation and want to save in transaction table id-s of both field fromAccount and toAccount but I got an Exception, which you can see below. I understand that it happens because of mapping on the same field (account_id) but how I can fix it if I should use id field? My code examlpe:

public class Account {
@OneToMany(fetch = FetchType.LAZY,
        mappedBy = "fromAcc",
        cascade = CascadeType.ALL)
private List<Transaction> withdrawTransactions = new ArrayList<>();

@OneToMany(fetch = FetchType.LAZY,
        mappedBy = "toAcc",
        cascade = CascadeType.ALL)
private List<Transaction> depositTransactions = new ArrayList<>();

and

public class Transaction {
@ManyToOne
@JoinColumn(name = "account_id")
private Account fromAcc;
@ManyToOne
@JoinColumn(name = "account_id")
private Account toAcc;

Exception which I got:

 Exception in thread "main" javax.persistence.PersistenceException: [PersistenceUnit: BankAppSimple] Unable to build Hibernate SessionFactory
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.persistenceException(EntityManagerFactoryBuilderImpl.java:1012)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:938)
at org.hibernate.jpa.HibernatePersistenceProvider.createEntityManagerFactory(HibernatePersistenceProvider.java:56)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:79)
at javax.persistence.Persistence.createEntityManagerFactory(Persistence.java:54)
at bank.app.simple.util.JpaUtil.getEntMngFactoryInstance(JpaUtil.java:18)
at bank.app.simple.util.JpaUtil.createEntityManager(JpaUtil.java:30)
at bank.app.simple.daoimpl.ExchangeRateDaoImpl.isCurrencyExist(ExchangeRateDaoImpl.java:19)
at bank.app.simple.serviceimpl.ExchangeRateServiceImpl.addRate(ExchangeRateServiceImpl.java:19)
at bank.app.simple.Main.fillTables(Main.java:46)
at bank.app.simple.Main.main(Main.java:26)

and

Caused by: org.hibernate.MappingException: Repeated column in mapping for entity: bank.app.simple.entity.Transaction column: account_id (should be mapped with insert="false" update="false")
at org.hibernate.mapping.PersistentClass.checkColumnDuplication(PersistentClass.java:862)
at org.hibernate.mapping.PersistentClass.checkPropertyColumnDuplication(PersistentClass.java:880)
at org.hibernate.mapping.PersistentClass.checkColumnDuplication(PersistentClass.java:902)
at org.hibernate.mapping.PersistentClass.validate(PersistentClass.java:634)
at org.hibernate.mapping.RootClass.validate(RootClass.java:267)
at org.hibernate.boot.internal.MetadataImpl.validate(MetadataImpl.java:343)
at org.hibernate.boot.internal.SessionFactoryBuilderImpl.build(SessionFactoryBuilderImpl.java:461)
at org.hibernate.jpa.boot.internal.EntityManagerFactoryBuilderImpl.build(EntityManagerFactoryBuilderImpl.java:935)
... 9 more
Questioner
Reni21
Viewed
60
t4dohx 2019-07-03 21:12

I think you forgot to set join column in your Transaction entity. Just replace FROM_ACC_COLUMNand TO_ACC_COLUMN with corresponding column names from your transaction table.

public class Transaction {

    @ManyToOne
    @JoinColumn(name = "FROM_ACC_COLUMN", referencedColumnName = "account_id")
    private Account fromAcc;

    @ManyToOne
    @JoinColumn(name = "TO_ACC_COLUMN", referencedColumnName = "account_id")
    private Account toAcc;

}

And personally I'd not go for CascadeType.ALL in this case, try {CascadeType.PERSIST, CascadeType.MERGE} instead.