Spring Boot中@OneToMany关联未映射类触发AnnotationException的解决

问题背景 #

我正在学习Java Spring Boot 2.7.15，开发一个学习管理系统练手项目，需要为讲师（Instructor）与社交链接（InstructorSocial）建立@OneToMany关联，过程中遇到问题，尝试多种方案后仍回到同一错误。

初始错误代码 #

InstructorEntity.java #

@Entity
@Table(name = "instructor", uniqueConstraints = @UniqueConstraint(columnNames = {"email"}))
public class InstructorEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String uuid;
    private String firstName;
    private String lastName;
    private String profession;
    @Column(columnDefinition = "longtext", length = 65555)
    private String bio;
    @Column(unique = true)
    private String email;
    private String phone;
    private String website;

    @OneToMany(
            cascade = CascadeType.ALL,
            orphanRemoval = true
    )
    @JoinTable(
            name = "instructor_social",
            joinColumns = {@JoinColumn(name = "instructor_id", referencedColumnName = "id")},
            inverseJoinColumns = {@JoinColumn(name = "instructor_social_id", referencedColumnName = "id")}
    )
    private List<InstructorSocial> socials = new ArrayList<>();

    public InstructorEntity() {
    }

    public InstructorEntity(long id, String uuid, String firstName, String lastName, String profession, String bio, String email, String phone, String website) {
        this.id = id;
        this.uuid = uuid;
        this.firstName = firstName;
        this.lastName = lastName;
        this.profession = profession;
        this.bio = bio;
        this.email = email;
        this.phone = phone;
        this.website = website;
    }

    // Getters and Setters
}

InstructorSocialEntity.java #

@Entity
@Table(name = "instructor_social")
public class InstructorSocialEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String uuid;
    private String name;
    private String image;

    public InstructorSocialEntity() {
    }

    public InstructorSocialEntity(long id, String uuid, String name, String image) {
        this.id = id;
        this.uuid = uuid;
        this.name = name;
        this.image = image;
    }

    // Getters and Setters
}

修正后可运行代码 #

Instructor.java #

@Entity
@Table(name = "instructor", uniqueConstraints = @UniqueConstraint(columnNames = {"email"}))
public class Instructor {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String uuid;
    private String firstName;
    private String lastName;
    private String profession;
    @Column(columnDefinition = "longtext", length = 65555)
    private String bio;
    @Column(unique = true)
    private String email;
    private String phone;
    private String website;

    @OneToMany(
            mappedBy = "instructor",
            cascade = CascadeType.ALL,
            orphanRemoval = true
    )
    private List<InstructorSocial> socials = new ArrayList<>();

    public Instructor() {
    }

    public Instructor(long id, String uuid, String firstName, String lastName, String profession, String bio, String email, String phone, String website) {
        this.id = id;
        this.uuid = uuid;
        this.firstName = firstName;
        this.lastName = lastName;
        this.profession = profession;
        this.bio = bio;
        this.email = email;
        this.phone = phone;
        this.website = website;
    }
}

InstructorSocial.java #

@Entity
@Table(name = "instructor_social")
public class InstructorSocial {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private long id;
    private String uuid;
    private String name;
    private String image;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "instructor_id")
    private Instructor instructor;

    public InstructorSocial() {
    }

    public InstructorSocial(long id, String uuid, String name, String image) {
        this.id = id;
        this.uuid = uuid;
        this.name = name;
        this.image = image;
    }
}

补充问题 #

修正关联配置后应用可正常运行，但出现新问题：将社交链接添加到讲师的socials列表时，数据库中已新增记录，但Instructor.socials列表未更新。相关Service代码如下：

InstructorService.java #

InstructorSocial social = new InstructorSocial();
social.setUuid();
social.setName(instructorSocial.getName());
social.setImage(instructorSocial.getImage());

foundInstructor.getSocials().add(social);
instructorRepository.save(foundInstructor);

补充问题解决方案 #

排查发现问题出在Service层的getAllInstructors()方法实现上，未正确映射关联的社交链接列表。修正后的代码如下：

service/InstructorServiceImpl.java #

@Override
    public List<Instructor> getAllInstructors() {
        return instructorRepository
                .findAll().stream()
                .map(instructorEntity -> new Instructor(
                        instructorEntity.getId(),
                        instructorEntity.getUuid(),
                        instructorEntity.getFirstName(),
                        instructorEntity.getLastName(),
                        instructorEntity.getProfession(),
                        instructorEntity.getBio(),
                        instructorEntity.getEmail(),
                        instructorEntity.getPhone(),
                        instructorEntity.getWebsite(),
                        instructorEntity.getSocials()
                                .stream()
                                .map(instructorSocialEntity -> new InstructorSocial(
                                        instructorSocialEntity.getId(),
                                        instructorSocialEntity.getUuid(),
                                        instructorSocialEntity.getName(),
                                        instructorSocialEntity.getImage()
                                ))
                                .collect(Collectors.toList())
                ))
                .collect(Collectors.toList());
    }

内容的提问来源于stack exchange，提问作者hawkinside_out