ManyToOne ClassCastException

Question

我正在尝试创建一个“简单”的一个或多个或多个的关系。我得到以下例外情况：

有人能告诉我我做错了什么吗？

下面你可以找到我的两个实体。

提前谢谢你。

  import javax.persistence.OneToMany;
@Entity
@Table(uniqueConstraints={@UniqueConstraint(columnNames={"questionGroupID","questionID"})})
public class QuestionGroupEntity implements Serializable{

    private static final long serialVersionUID = 1796640204447018439L;

    @Id
    @NotEmpty
    @Column(name="question_group_id")
    private String questionGroupID;

    @NotEmpty
    private String label;


    @NotEmpty
    private String questionID;


    @OneToMany(fetch=FetchType.EAGER,targetEntity=QuestionGroupMappingEntity.class,mappedBy="questionGroup")
    List<QuestionGroupMappingEntity> questionGroupMappings;

而且

import javax.persistence.ManyToOne;
    @Entity
    @Table(uniqueConstraints={@UniqueConstraint(columnNames={"questionGroupID","questionID","answerID"})})
    public class QuestionGroupMappingEntity implements Serializable {

        private static final long serialVersionUID = 8437546139229082305L;

        @Id
        @SequenceGenerator(name="groupMappingIDGenerator")
        @GeneratedValue(generator="groupMappingIDGenerator",strategy=GenerationType.AUTO)
        private String groupMappingID;

        @NotEmpty
        private String questionID;

        @NotEmpty
        private String questionGroupID;

        @NotEmpty
        private String answerID;

        @ManyToOne(fetch=FetchType.EAGER)
        @JoinColumn(name="question_group_id")
        private QuestionGroupEntity questionGroup;

Answer 1

谢谢你的回答。我通过添加spring.jpa.hibernate.ddl-auto=update spring.jpa.generate-ddl=true属性解决了这个问题。问题是spring-data无法更新模式。