如何修复 org.hibernate.MappingException？

Question

我是 JPA 的新手，在尝试设置 UserContact 实体时出现此错误。

 Caused by: org.hibernate.MappingException: Could not determine type for: java.util.Set, at table: USER_ID, for columns: [org.hibernate.mapping.Column(userContact)]

我有 2 个实体类和一个用于复合键的 @Embeddable 类。 这个问题似乎有很多解决方案，所以我在 getter/setter 和字段中混合和匹配了属性。 我试过@JsonBackReference 和@JsonManagedReference、@ElementCollection 和其他注释。 使用@Access(AccessType.PROPERTY) 确实启动了服务器，但是在尝试执行数据库操作时给了我这个错误。

 org.codehaus.jackson.map.JsonMappingException: failed to lazily initialize a collection of role:

任何帮助，将不胜感激。 这是我的实体。

用户

@Entity
@Table(name = "USER_RECORD")

public class User {

private UserRecordId id;    
private String name;
private String address;

@Column
@ElementCollection(targetClass=UserContact.class)
private Set<UserContact> userContact = new HashSet<UserContact>(0);

        @EmbeddedId
        @AttributeOverrides({
        @AttributeOverride(name = "userId", column = @Column(name = "USER_ID", nullable = false)),
        @AttributeOverride(name = "userId2", column = @Column(name = "USER_ID2", nullable = false)) })
public UserRecordId getId() {
    return this.id;
}
public void setId(UserRecordId id) {
    this.id = id;
}

@OneToMany(fetch = FetchType.EAGER, mappedBy = "user")
public Set<UserContact> getUserContact() {
    return this.userContact;
}
public void setUserContact(Set<UserContact> userContact) {
    this.userContact = userContact;
}   

@Column(name = "USER_NAME", nullable = false)
public String getName() {
    return this.name;
}
public void setName(String name) {
    this.name = name;
}

@Column(name = "USER_ADDRESS", nullable = false)
public String getAddress() {
    return this.address;
}
public void setAddress(String address) {
    this.address = address;
}

用户联系方式

@Entity
@Table(name = "USER_CONTACT")
public class UserContact {

private String userContactId;
private String name;
private String country;

private User user;

@Id
@Column(name = "USER_CONTACT_ID", unique = true, nullable = false)
public String getUserContactId() {
    return this.userContactId;
}
public void setUserContactId(String userContactId) {
    this.userContactId = userContactId;
}

@ManyToOne(fetch = FetchType.EAGER)
@JoinColumns({
        @JoinColumn(name = "USER_ID", referencedColumnName = "USER_ID"),
        @JoinColumn(name = "USER_ID2", referencedColumnName = "USER_ID2") })
public User getUser() {
    return this.user;
}
public void setUser(User user) {
    this.user = user;
}

@Column(name = "CONTACT_NAME", nullable = false)
public String getName() {
    return this.name;
}
public void setName(String name) {
    this.name = name;
}

@Column(name = "CONTACT_COUNTRY", nullable = false)
public String getCountry() {
    return this.country;
}
public void setCountry(String country) {
    this.country = country;
}

用户记录 ID/可嵌入

@Embeddable
public class UserRecordId

private String userId;
private String userId2;


@Column(name = "USER_ID", nullable = false)
public String getUserId() {
    return this.userId;
}
.../////getUserid2
......
.....

override equals & hash code

Answer 1

您似乎已经注释了一个字段和一个 getter (userContact)。 您应该使用 FIELD 或 PROPERTY 访问，但不能同时使用（尤其是对于同一个字段！）。

此外，您还一次将其注释为ElementCollection ，一次将其注释为OneToMany 。 当元素是实体时，不能两者兼而有之，当然也不能是ElementCollection 。