休眠一对多映射注释问题

Question

我是Hibernate的新手。我有两个表Team(父)和Product(子)，TEAM_ID列作为关系，每个团队将有多个产品，每个产品将有一个团队。我已经创建了具有团队类中@OneToMany映射的实体类，并在Product类中创建了@ManyToOne。

我需要掩盖以下场景，

1. 在团队是新团队时保存产品和团队
2. 如果团队已经可用，则仅保存产品

当我尝试保存产品时，它再次尝试保存团队抛出约束错误。 请帮忙。

Team:
@Entity
@Table(name = "TEAM")
public class Team implements Serializable{
private static final long serialVersionUID = 5819170381583611288L;
@Id
@SequenceGenerator(name="teamIdSeq",sequenceName="team_id_seq",allocationSize=1)
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="teamIdSeq")
@Column(name="TEAM_ID", updatable = false, nullable = false, unique = true)
private int teamId;
@Column(name="NAME", nullable = false, unique = true)
private String teamName;
@Column(name="DESCRIPTION", nullable = false)
private String teamDesc;
@Column(name="CONTACTS", nullable = false)
private String contacts;
@Column(name="APPROVER_NAME", nullable = false)
private String approverName;
@Column(name="APPROVAL_STATUS", nullable = false)
private int approvalStatus;
@Temporal(TemporalType.DATE)
@Column(name="CREATED_ON", nullable = false)
private Date createdOn;
@Column(name="CREATED_BY", nullable = false)
private String createdBy;
@Temporal(TemporalType.DATE)
@Column(name="MODIFIED_ON", nullable = false)
private Date modifiedOn;
@Column(name="MODIFIED_BY", nullable = false)
private String modifiedBy;
@OneToMany(fetch = FetchType.LAZY, mappedBy="team", cascade = CascadeType.ALL)
private Set<Product> products;
//setters and getters   
}
Product:
@Entity
@Table(name = "PRODUCT", uniqueConstraints = {@UniqueConstraint(columnNames = {"PRODUCT_ID", "TEAM_ID"})})
public class Product implements Serializable{
private static final long serialVersionUID = 5819170381583611288L;
@Id
@SequenceGenerator(name="productIdSeq", sequenceName="product_id_seq",allocationSize=1)
@GeneratedValue(strategy=GenerationType.SEQUENCE, generator="productIdSeq")
@Column(name="PRODUCT_ID", updatable = false, nullable = false)
private int productId;
@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "TEAM_ID")
private Team team;
@Column(name="NAME", nullable = false, unique = true)
private String productName;
@Column(name="DESCRIPTION", nullable = true)
private String productDesc;
@Column(name="APPROVER_NAME", nullable = false)
private String approverName;
@Column(name="APPROVAL_STATUS", nullable = false)
private int approvalStatus;
@Temporal(TemporalType.DATE)
@Column(name="CREATED_ON", nullable = false)
private Date createdOn;
@Column(name="CREATED_BY", nullable = false)
private String createdBy;
@Temporal(TemporalType.DATE)
@Column(name="MODIFIED_ON", nullable = false)
private Date modifiedOn;
@Column(name="MODIFIED_BY", nullable = false)
private String modifiedBy;
@OneToMany(fetch = FetchType.LAZY, mappedBy="product")
private Set<Form> forms;
//setters and getters   
}
DAO:
@Repository
@EnableTransactionManagement
public class KMDBDAOImpl implements KMDBDAO {
@Autowired
private SessionFactory sessionFactory;
public void addTeam(Team team) {
Product product = new Product(team, "BMA" + Math.random(), "UI Tool", "test", 
1, new Date(), "test", new Date(), "test");
Set<Product> products = new HashSet<Product>();
products.add(product);
team.setProducts(products);
if(getTeam(team.getTeamName()) != null) {
product.setTeam(getTeam(team.getTeamName()));
sessionFactory.getCurrentSession().saveOrUpdate(product);
} else {
sessionFactory.getCurrentSession().saveOrUpdate(team);
}
}
public Team getTeam(String teamName) {
Query query = sessionFactory.getCurrentSession().createQuery("from Team where teamName = :name");  
query.setString("name", "teamName");
return (query.list().size() > 0 ? (Team) query.list().get(0) : null);
}

Answer 1

只有在团队是新实体时，才应在团队上设置产品列表。所以：

Set<Product> products = new HashSet<Product>();
products.add(product);
if(getTeam(team.getTeamName()) != null) {
product.setTeam(getTeam(team.getTeamName()));
sessionFactory.getCurrentSession().saveOrUpdate(product);
} else {
team.setProducts(products);
sessionFactory.getCurrentSession().saveOrUpdate(team);
}

Answer 2

我给你一些一对多关系的示例代码，请通过它，如果有什么问题，让我 kn ....我有 2 张桌子 1.产品 2.SKU 我的条件是，一个产品有很多 SKU ...

产品.java

@LazyCollection(LazyCollectionOption.FALSE)
@ElementCollection(targetClass=Product.class)
@OneToMany(mappedBy="product" , cascade=CascadeType.MERGE)
private List<Sku> listSkuOrders = new ArrayList<>();

货号.java

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumn(name = PRODUCT_ID , nullable = false)
private Product product;