我有一个简单的银行应用程序，其中有“帐户”和“交易”实体。一个帐户保留提款并存入交易（它们可以在两个帐户之间，也可以在account＆ATM之间（在相应的字段中为null）。我使用@ManyToOne和@OneToMany批注，并希望将这两个字段保存在交易表id-s中fromAccount和toAccount但我遇到了一个异常，您可以在下面看到，我理解它是由于映射到同一字段（account_id）而发生的，但是如果我应该使用id字段，该如何解决呢？
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<>();
和
public class Transaction {
@ManyToOne
@JoinColumn(name = "account_id")
private Account fromAcc;
@ManyToOne
@JoinColumn(name = "account_id")
private Account toAcc;
我得到的例外：
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)
和
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
我认为您忘记在Transaction实体中设置连接列。只需用事务表中的FROM_ACC_COLUMN和替换TO_ACC_COLUMN为相应的列名即可。
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;
}
就我个人CascadeType.ALL而言，在这种情况下我不会去尝试{CascadeType.PERSIST, CascadeType.MERGE}。