java - Hibernate - 一次保存映射三个表
问题描述
我正在尝试创建一个将使用 Hibernate 将对象存储到数据库的项目。
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,那么一切正常。但是,我有一个案例,三个表之间存在连接。这些表是资产、货币价值和货币类型(见下文)。
插入资产时,必须(由用户)提供货币值类型以及货币类型。Asset 拥有与 MonetaryValueType 的 OneToOne 关系,而 MonetaryValueType 拥有与 CurrencyType 表的 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,每次我创建资产对象并调用资产服务来保存元素时,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,要么在货币字段中插入错误的列名称(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-----
每个实体都有自己的 DAO、DAOImpl、Service 和 ServiceImpl 类。例如,对于资产类别,DAOImpl 和 ServiceImpl 可以在下面找到:
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;
}
...
我用来填充资产类(及其所有子类)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,都会出现以下错误:
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,休眠创建的列(currency_id 而不是currencyID)与我的数据库表不相符。
解决方案
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
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