Hibernate中的@MapKeyColumn默认值错误

Question

我正在尝试为@MapKeyColumn实现以下示例。Company和Persons之间存在OnetoMany的关系。但是，当我尝试坚持这个人实例时，我会遇到以下错误，因为那是关系的所有者：

Caused by: java.sql.SQLException: Field 'name_emp' doesn't have a default value
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:129)
at com.mysql.cj.jdbc.exceptions.SQLError.createSQLException(SQLError.java:97)
at com.mysql.cj.jdbc.exceptions.SQLExceptionsMapping.translateException(SQLExceptionsMapping.java:122)
at com.mysql.cj.jdbc.ClientPreparedStatement.executeInternal(ClientPreparedStatement.java:975)
at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1114)
at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdateInternal(ClientPreparedStatement.java:1062)
at com.mysql.cj.jdbc.ClientPreparedStatement.executeLargeUpdate(ClientPreparedStatement.java:1383)
at com.mysql.cj.jdbc.ClientPreparedStatement.executeUpdate(ClientPreparedStatement.java:1047)
at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:208)
... 20 more

个人实体

 @Entity
public class Person {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    int id;
    String name;
    @ManyToOne(cascade=CascadeType.PERSIST)
//@JoinColumn(name="company_id")
    Company company;
    public Person()
    {}
    public Person(String name) {
        super();
        this.name = name;
    }
    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Company getcompany() {
        return company;
    }

    public void setcompany(Company c) {
        this.company = c;
    }
}

公司实体

 @Entity
public class Company {
    @Id
    @GeneratedValue(strategy=GenerationType.AUTO)
    int id;
    String name;
    @OneToMany(cascade=CascadeType.PERSIST,mappedBy="company")
    @MapKeyColumn(name="name_emp")
    Map<String,Person> persons= new HashMap<>();
    public Company()
    {}

    public Company(String name) {
        super();
        this.name = name;
    }
    public Map<String,Person> getPersons() {
        return persons;
    }
    public void setPersons(Map<String,Person> persons) {
        this.persons = persons;
    }

    public int getId() {
        return id;
    }
    public void setId(int id) {
        this.id = id;
    }
    public String getName() {
        return name;
    }
    public void setName(String name) {
        this.name = name;
    }
}

维护

    Person p1 = new Person("jack");
    Company c= new Company("ABCORP");
    p1.setcompany(c);
    session.persist(p1);

Answer 1

可能会出现问题，因为该关系未在公司实例中设置。

您可以通过致电c.getPersons().add(p1.getName(), p1)或将setcompany(...)方法更改为

来尝试将其添加到公司以太币中

public void setcompany(Company c) {
    c.getPersons().add(this.getName(), this)
    this.company = c;
}