java - 如何在 Spring Data jpa 中应用本机联接查询?
问题描述
这是我的实体类。
JobPost.java
@Entity
@Table(name = "job_post")
public class JobPost {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "job_post_id")
private Long jobPostId;
@Column(name = "job_title")
private String jobTitle;
@Column(name = "job_description")
private String jobDescription;
@Column(name = "vacancy")
private int vacancy;
@Column(name = "posted_date")
@JsonFormat(pattern = "yyyy-MM-dd")
private Date postedDate;
@Column(name = "total_applicants")
private int totalApplicants;
}
JobApplication.java
@Entity
@Table(name = "job_application")
public class JobApplication {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "job_application_id")
private Long jobApplicationId;
@Column(name = "job_post_id")
private Long jobPostId;
@Column(name = "applicant_id")
private Long applicantId;
}
申请人.java
@Entity
@Table(name = "applicant")
public class Applicant {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "applicant_id")
private Long applicantId;
@Column(name = "applicant_name")
private String applicantName;
@Column(name = "applicant_mobile_no")
private String applicantMobileNo;
@Column(name = "applicant_email")
private String applicantEmail;
}
我的主要目标是在JobPostId上列出申请人列表。我是 Spring data JPA 的新手。JPA 映射是否正确?我不知道应该触发哪个查询才能根据 jobPostId 获取申请者列表。
解决方案
我建议使用 JpaMappings 并使用 SpringData 而不是使用本机查询。遵循的步骤: 多对多:
使用 JoinTable 直接映射 JobPost 和申请人,而不是创建单独的类。
链接寻求帮助: https ://attacomsian.com/blog/spring-data-jpa-many-to-many-mapping
使用 SpringData JPA findOne 或 findById 方法(取决于 spring 版本)。如果您使用 EAGER fetch,那么它将为您提供与 JobPost Id 关联的所有申请人。
一对多
保留 JobApplication 类并使用 OneToMany 注释。
链接寻求帮助: https ://attacomsian.com/blog/spring-data-jpa-one-to-many-mapping
询问:
@Query("select a from JobPost j inner join j.jobApplicantList ja inner join ja.applicant a where j.jobPostId=:jobPostId")
List<String> findAllJobApplicants(@Param("jobPostId") Long jobPostId);