java Hibernate 映射 - “无法确定类型”

Hibernate mapping - "Could not determine type"

提问by Pool

I currently have the following objects persisting successfully:

我目前有以下对象成功持久化：

• Personfirst name, etc.
• Examstitle, date, etc.

• 人名等
• 考试名称、日期等。

I'd like to now create a third table Exam results. For this table I believe it should be person ID, exam ID and result, and this is a many to many relationship.

我现在想创建第三个表Exam results。对于这张表，我认为应该是人 ID、考试 ID 和结果，这是一个多对多的关系。

@Entity
public class ExamResult {
    private Exam exam;
    private Person person;
    private double value;

    @Id
    @ManyToOne( cascade = {CascadeType.PERSIST, CascadeType.MERGE} )
    @JoinColumn(name="EXAM_ID")
    public Exam getExam() {
        return exam;
    }
    public void setExam(Exam exam) {
        this.exam = exam;
    }

    @Id
    @ManyToOne( cascade = {CascadeType.PERSIST, CascadeType.MERGE} )
    @JoinColumn(name="PERSON_ID")
    public Person getPerson() {
        return person;
    }
    public void setPerson(Person person) {
        this.person = person;
    }

    public double getValue() {
        return value;
    }
    public void setValue(double value) {
        this.value = value;
    }
}

The error:

错误：

org.hibernate.MappingException: Could not determine type for: Person, at table: ExamResult, for columns: [org.hibernate.mapping.Column(person)]

org.hibernate.MappingException：无法确定类型：Person，在表：ExamResult，对于列：[org.hibernate.mapping.Column(person)]

I think I may be going about this the wrong way, but I can't work out how to proceed with this relationship from the tutorial.

我想我可能会以错误的方式解决这个问题，但是我无法从教程中弄清楚如何处理这种关系 。

Any ideas?

有任何想法吗？

回答by William Witter da Silva

You can't have multiple @Idannotations in the same entity. Use a composite ID instead. Example.

@Id同一实体中不能有多个注释。请改用复合 ID。 例子。