上下文
我正在尝试创建一个简单的API来学习Spring Boot和JPA。信息存储在H2数据库中。
我有2个实体:mission
和user
。
几个用户被分配到一个任务。用户可以分配到不同的任务。
所以,我的班级Mission
有一个属性private ArrayList<User> users;
。
目的
我的目标是创建一些请求:
IP/missions/123456/users
:获取分配给任务123456
的所有用户IP/missions/456789
:分配给456789
任务的用户所以,绑定两个实体。
问题
但我不知道如何存储/绑定相对于mission
和user
的信息。好的方法是用方案Assignements(id_user, id_mission)
创建一个“关联表”?
感谢帮助!
编辑1:代码
实体使命
@Entity
public class Mission{
@Id
private String id;
private String name;
private Date start;
private Date end;
private ArrayList<User> users;
private int status;
public Mission() {
}
public Mission(String name, Date start, Date end) {
this.name = name;
this.start = start;
this.end = end;
this.status = 0;
}
// getters and setters
}
实体用户
@Entity
public class User {
@Id
private String id;
private String name;
public User() {
}
public User(String name) {
this.name = name;
}
// getters and setters
}
SQL
我使用SQL脚本。目前,脚本看起来像:
INSERT INTO mission (id, name, start, end, status) VALUES ('de7d9052-4961-4b4f-938a-3cd12cbe1f82', 'mission 1', '2019-02-11', '2019-02-13', 0)
INSERT INTO mission (id, name, start, end, status) VALUES ('425e7701-02c6-4de3-9333-a2459eece1c8', 'mission 2', '2019-02-10', '2019-02-15', 0)
编辑2:新代码(使用@ManyToMany)
实体
@Entity
public class Mission {
@Id
private String missionid;
private String namemission;
private Date start;
private Date end;
@ManyToMany
@JoinTable(name = "mission_user",
joinColumns = @JoinColumn(name = "missionid"),
inverseJoinColumns = @JoinColumn(name = "userid")
)
private Set<User> users = new HashSet<>();
private int status;
public Mission() {}
public Mission(String name, Date start, Date end) {
this.namemission = name;
this.start = start;
this.end = end;
this.status = 0;
}
}
@Entity
public class User {
@Id
private String iduser;
private String nomuser;
@ManyToMany(mappedBy = "users")
private Set<Mission> missions = new HashSet<>();
public User() {}
public User(String nom) {
this.nomuser = nom;
}
}
库
@RepositoryRestResource(collectionResourceRel = "mission")
public interface MissionResource extends JpaRepository<Mission, String> {
...
}
@RepositoryRestResource(collectionResourceRel = "user")
public interface UserResource extends JpaRepository<User, String> {
...
}
休息控制器
@RestController
@RequestMapping(value = "/missions", produces = MediaType.APPLICATION_JSON_VALUE)
@ExposesResourceFor(Mission.class)
public class MissionRepresentation {
private final MissionResource missionResource;
private final UserResource userResource;
public MissionRepresentation(MissionResource missionResource, UserResource userResource) {
this.missionResource = missionResource;
this.userResource = userResource;
}
// mapping
}
最好的方法是实现一个连接表,就像你说的那样。这将是这样的:
create table mission_user (
mission_id int,
user_id int,
primary key (mission_id, user_id)
)
然后使用这张表作为@ManyToMany
的映射或实体的MissionUser
,并将User
和Mission
映射为@OneToMany
。
任务类将具有:
@Entity
public class Mission {
...
@ManyToMany(mappedBy = "missions")
private List<User> users;
...
}
和用户类将具有:
@Entity
public class User {
...
@ManyToMany(mappedBy = "users")
private List<Mission> missions;
...
}
这将在您的数据库中创建一个表,其名称类似于:mission_uesrs,它将具有missionId和userId作为唯一列。