如何修復 org.hibernate.MappingException？

Question

我是 JPA 的新手，在嘗試設置 UserContact 實體時出現此錯誤。

 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 個實體類和一個用於復合鍵的 @Embeddable 類。 這個問題似乎有很多解決方案，所以我在 getter/setter 和字段中混合和匹配了屬性。 我試過@JsonBackReference 和@JsonManagedReference、@ElementCollection 和其他注釋。 使用@Access(AccessType.PROPERTY) 確實啟動了服務器，但是在嘗試執行數據庫操作時給了我這個錯誤。

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

任何幫助，將不勝感激。 這是我的實體。

用戶

@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;
}

用戶聯系方式

@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;
}

用戶記錄 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

您似乎已經注釋了一個字段和一個 getter (userContact)。 您應該使用 FIELD 或 PROPERTY 訪問，但不能同時使用（尤其是對於同一個字段！）。

此外，您還一次將其注釋為ElementCollection ，一次將其注釋為OneToMany 。 當元素是實體時，不能兩者兼而有之，當然也不能是ElementCollection 。