[英]How to fetch FetchType.LAZY associations with JPA and Hibernate in a Spring Controller
[英]How to join fetch two associations with JPA/Hibernate
我是Hibernate的新手,真的需要你們的幫助....我有以下課程:UserActionPerUserResult
@Entity
@Table(name = "user_action_per_user_result")
public class UserActionPerUserResult {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
@Column(name = "user_email", nullable = false)
private String userEmail;
@ManyToOne
@JoinColumn(name = "user_action_id", nullable = false)
private UserAction userAction;
@ManyToMany(fetch = FetchType.LAZY)
@JoinTable(name="user_action_per_user_result_email_message",
joinColumns={@JoinColumn(name="user_action_per_user_result_id", referencedColumnName="id")},
inverseJoinColumns={@JoinColumn(name="email_message_id", referencedColumnName="id")})
@JsonIgnore
private List<EmailMessage> emailMessages;
....getters/setter....
}
在MYSQL中,UserActionPerUserResult是一個表,對於電子郵件消息,還有另一個名為UserActionPerUserResultEmailMessage的表,該表具有與表UserActionPerUserResult的id相關聯的電子郵件消息。
我將所有數據存儲在MySQL表中,但是我無法查詢它。 我需要編寫一個查詢來獲取emailMessages列表。 我正在嘗試以下,但它正在拋出異常。
TypedQuery<UserActionPerUserResult> messagesQuery = entityManager.createQuery(
"SELECT e from UserActionPerUserResult e JOIN UserActionPerUserResult.emailMessages e1 WHERE e.id = 1 and e.userAction = 1", UserActionPerUserResult.class);
List<UserActionPerUserResult> resultList = messagesQuery.getResultList();
嘗試編寫這樣的查詢:
TypedQuery<UserActionPerUserResult> messagesQuery = entityManager.createQuery(
"SELECT e from UserActionPerUserResult e JOIN FETCH e.emailMessages em WHERE e.id = 1 and e.userAction.id = 1", UserActionPerUserResult.class);
List<UserActionPerUserResult> resultList = messagesQuery.getResultList();
聲明:本站的技術帖子網頁,遵循CC BY-SA 4.0協議,如果您需要轉載,請注明本站網址或者原文地址。任何問題請咨詢:yoyou2525@163.com.