java - Hibernate - 通过一次保存映射三个表

Question

我正在尝试创建一个项目，该项目将使用 Hibernate 将对象存储到数据库中。

如果我只是插入(保存)一个不包含与另一个表的映射的对象，则一切正常。但是，我有一个情况，三个表之间存在连接。这些表是 Asset、MonetaryValue 和CurrencyType(见下文)。

插入 Assets 时，必须(由用户)提供货币值类型以及货币类型。 Asset 与MonetaryValueType 保持OneToOne 关系，MonetaryValueType 与CurrencyType Table 保持OneToOne 关系。更具体地说，您将在下面找到数据库表。

Asset(asset_id,ownerIID,valueID,samID), where valueID is the foreign key to the MonetaryValueType Table (OneToOne undirectional mapping)

MonetaryValueType(mvID, mValue,currencyId), where currencyID is the foreign key to the CurrencyType Table (OneToOne undirectional mapping)

CurrencyType(currencyID,currField,currValue,currSymbol).

问题是，每次我创建 Assets 对象并调用 Assets 服务来保存元素时，Hibernate 要么创建一个选择查询，尝试从我从未定义的数据库表中进行选择，要么插入货币字段列名错误(即currency_field而不是currField等)

我尝试过使用所有 Cascade 类型，但似乎没有任何效果。

Asset.java

@Entity
@Table(name="asset")
public class Asset implements java.io.Serializable{

    @Id
    @Column(name="assetID", unique = true, nullable = false)
    private long assetID;

    @Column(name="ownerID")
    private long ownerID;

    @OneToOne
    @JoinColumn(name="valueID")
    private MonetaryValueType monetaryValueType;

    @Column(name="samID")
    private long samID;
------------Constructor, Getters , Setters-----

MonetaryValueType.java

@Entity
@Table(name="monetaryvaluetype")
public class  MonetaryValueType{

    @Id
    @Column(name="mvID",nullable = false,unique = true)
    private Long id;

    @Column(name="mValue")
    private double mValue;

    @OneToOne
    @JoinColumn(name="currencyId")
    private CurrencyType currency;
------------Constructor, Getters , Setters-----

CurrencyType.java

@Entity
@Table(name="currencytype")
public class CurrencyType implements java.io.Serializable {

    @Id
    @Column(name="currencyID")
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private int currencyID;

    @Column(name="currField")
    private  String currField;

    @Column(name="currValue")
    private String currValue;

    @Column(name="currSymbol")
    private String currSymbol;
------------Constructor, Getters , Setters-----

每个实体都拥有自己的 DAO、DAOImpl、Service 和 ServiceImpl 类。例如，对于 Assets 类别，可以在下面找到 DAOImpl 和 ServiceImpl:

AssetDAOImpl.java

@Repository
public class AssetDAOImpl implements AssetDAO{
    private Logger logger   = LoggerFactory.getLogger(this.getClass());
    //entity manager field
    @Autowired
    private EntityManager entityManager;




    @Override
    public List<Asset> findAll() {
        Session currentSession = entityManager.unwrap(Session.class);
        //create a query
        Query theQuery =
                currentSession.createQuery("from asset",Asset.class);
        //execute query and get result list
        List<Asset> aModelElements = theQuery.getResultList();
        //return the results
        return aModelElements;
    }

    @Override
    public Asset findById(int theId) {
        return null;
    }

    @Override
    public Asset insert(Asset assetElement) {

        //Session currentSession = entityManager.unwrap(Session.class);
        boolean success = false;
        try {

            entityManager.persist(assetElement);
            logger.info("Asset -> {}", assetElement);
            return assetElement;
        }
        catch(Exception e){
            e.printStackTrace();
        }
        return null;
    }

AssetServiceImpl.java

@Service
public class AssetServiceImpl implements AssetService {

    private Logger logger   = LoggerFactory.getLogger(this.getClass());
    private AssetDAO assetDAO;

    @Autowired
    public AssetServiceImpl(AssetDAO theAssetDAO){
        assetDAO=theAssetDAO;
    }

    @Override
    @Transactional
    public List<Asset> findAll() {

        return assetDAO.findAll();
    }

    @Override
    @Transactional
    public Asset findById(int theId) {
        return assetDAO.findById(theId);
    }

    @Override
    @Transactional
    public Asset insert(Asset theAsset) {
        assetDAO.insert(theAsset);
        return theAsset;

    }
...

我用来填充 Assets 类别(及其所有子类别)的类是:

 UniqueIDGenerator uniqueIDGenerator = new UniqueIDGenerator();
            CurrencyType currencyType = new CurrencyType();
            Asset asset = new Asset();
            MonetaryValueType monetaryValueType = new MonetaryValueType();

            currencyType.setCurrValue(ctx.value().monetaryValueType().currency().CurrencyType().getText());
            currencyType.setCurrSymbol("currency");

            monetaryValueType.setId(uniqueIDGenerator.nextId());
            monetaryValueType.setmValue(Double.parseDouble(ctx.value().monetaryValueType().mValue().getText()));
            monetaryValueType.setCurrency(currencyType);

            asset.setMonetaryValueType(monetaryValueType);
            asset.setAssetID(uniqueIDGenerator.nextId());
            asset.setOwner(uniqueIDGenerator.nextId());
            asset.setSamID(uniqueIDGenerator.nextId());
            assetService.insert(asset);

每当我调用上述类时，都会收到以下错误:

Hibernate: 
    insert 
    into
        element1
        (datefrom, dateto, description, name, statusid, samid) 
    values
        (?, ?, ?, ?, ?, ?)
2019-08-05 20:19:00 INFO  MyClass:63 - the result is:true
Hibernate: 
    select
        monetaryva_.mvid,
        monetaryva_.currency_id as currency3_57_,
        monetaryva_.m_value as m_value2_57_ 
    from
        monetaryvaluetype monetaryva_ 
    where
        monetaryva_.mvid=?
2019-08-05 20:19:01.084  WARN 56712 --- [nio-8080-exec-1] o.h.engine.jdbc.spi.SqlExceptionHelper   : SQL Error: 1054, SQLState: 42S22
2019-08-05 20:19:01.084 ERROR 56712 --- [nio-8080-exec-1] o.h.engine.jdbc.spi.SqlExceptionHelper   : Unknown column 'monetaryva_.currency_id' in 'field list'

如您所见，即使我使用了 @Column 注释，hibernate 创建的列(currency_id 而不是currencyID)也不符合我的数据库表。

Answer 1

在 application.properties 文件中使用以下两行

spring.jpa.hibernate.naming.implicit-strategy=org.hibernate.boot.model.naming.ImplicitNamingStrategyLegacyJpaImpl
spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl