I have one to many relation ship between a User and UserRole.
public class User {
#Id
#GeneratedValue
private long id;
#Column(unique = true)
private String username;
private String password;
#OneToMany(fetch=FetchType.EAGER)
#JoinTable(
name = "user_roles",
joinColumns = {#JoinColumn(name="userId")},
inverseJoinColumns = {#JoinColumn(name="roleId")}
)
private Collection<UserRole> roles;
}
and
public class UserRole {
#Id
#GeneratedValue
private long id;
#Column(unique = true)
private String roleName;
}
I am able to save a user at first. But when I try to save another user it rejects with an exception of duplicated entry on the junction table
One thing I noticed is when we have One-to-Many association the many side foreign key will be a primary key on the junction table. So, I need to make the relation Many-to-Many. So that the combination of both foreign keys will serve as a composite key.
Related
I have 2 tables namely user & user_session.
User table has user_id as a primary key which is referrers to user_session table.
Plus user_session has composite key including session_intime and user_id.
I have designed my entity in JPA. Now I want to map these two entities. I have tried to map these two tables. But my application build failed. Can you please help me out?
#Entity
#Table(name="user")
public class User {
#Id
#Email
#Column(name = "user_id")
private String userId;
#Column(name = "password")
private String password;
#Column(name = "fname")
private String fname;
#OneToMany(fetch = FetchType.LAZY)
#JoinColumn(name = "userId", referencedColumnName = "user_id")
private UserSession userSession;
}
#Entity
#Table(name="user_session")
public class UserSession{
#EmbeddedId
private UserSessionPK userSessionPK;
#Column(name = "remote_ip")
private String remoteIp;
}
#Embeddable
public class UserSessionPK implements Serializable {
private static final long serialVersionUID = 1L;
#Column(name = "user_id")
private String userId;
#Temporal(TemporalType.TIMESTAMP)
#Column(name = "time_in")
private Date timeIn;
}
I want to map user_id of User table to user_id of UserSessionPK. I am new to JPA, so I don't know how to map with embeddable class.
Remove the mappedBy attribute. This attribute is used when you have bidirectional relationship to indicate which side of the relationship is the owner.
But you will need to set the Foreign Key aka JoinColumn
#JoinColumn("user_id")
#OneToMany(fetch = FetchType.LAZY)
private UserSession userSession;
using spring data, I created User 1:N UserDog N:1 Dog relation. Both 1:N relations are unidirectional #ManyToOne with UserDog being the custom relation table.
User entity:
#Entity
public class User {
#Id
#GeneratedValue
private long id;
#Column(nullable = false)
private String name;
}
Dog entity:
#Entity
public class Dog {
#Id
#GeneratedValue
private long id;
#Column(nullable = false)
private String name;
}
User dog relation table:
#Entity
public class UserDog {
#Id
#GeneratedValue
private long id;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn
#OnDelete(action = OnDeleteAction.CASCADE)
private User user;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn
#OnDelete(action = OnDeleteAction.CASCADE)
private Dog dog;
#Column(nullable = false)
private Instant createdOn = Instant.now();
#Column
private Instant disabledOn;
}
Use case
Use case is to store history of User-Dog bindings, where the concrete Dog can be bound only to one User at the time. That's why I added createdOn and disabledOn columns to UserDog. disabledOn being null indicates that the relation is active and the Dog can't be assigned another User. If disabledOn is not null, then the record is stored only for evidence purposes and the Dog can be assigned to the same or another User again.
Question
How to ensure that the combination of Dog's id and disabledOn being null is unique in UserDog table?
In pseudo code I want something like this:
#Entity
#UniqueConstraint({#UniqueConstraint(this.dog.id), #NullConstraint(this.disabledOn)})
public class UserDog {...}
You can simply create a unique constraint for dogId and disabledOn.
It does add the limitation that no two relationships may end at the same time but this seems to fit your use case.
I'm trying to connect an entity (User) to entities they create which will be Surveys.
I have two repositories, one UserRepository and one SurveyRepository. I can load Surveys according to which User has them and currently they are all mapped by the User_ID, which is a field on the Survey entity.
However, when I try to remove a Survey, this removes my User whenever I define CascadeType.ALL.
But when I don't use that, I get another error "Caused by: java.sql.SQLIntegrityConstraintViolationException:"
I'm gussing this is all related to the password encryption I'm using, but I am not even trying to delete the User entity, I'm just deleting the Survey, which holds a reference, or an ID to the Survey..
I've tried CascadeType.All on both sides, and I've tried not having any CascadeType at all as well.. If I have it on both sides, this deletes the user whenever I tell my surveyRepository.delete(currentSurvey);
And whenever I don't have it on both sides, I get the exception above..
User Entity:
#Entity
#Table(name = "user")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "user_id")
private Long id;
#NotEmpty
#Email
#Column(unique = true)
private String email;
private String password;
#NotBlank
private String username;
#NotBlank
private String firstName;
#NotBlank
private String lastName;
#NotBlank private String role;
#OneToMany(fetch = FetchType.EAGER)
private Set<Survey> surveys = new HashSet<>();
Survey Entity:
#Entity
#Table(name = "survey")
public class Survey {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "survey_id")
private Long id;
private String title, creator, description;
private LocalDate date = LocalDate.now();
#OneToMany(orphanRemoval = true, cascade = CascadeType.ALL, fetch = FetchType.EAGER)
#JoinColumn(name = "survey_id")
#OrderBy("position ASC")
private Set<Question> questions = new HashSet<>();
#ManyToOne(fetch = FetchType.EAGER)
#JoinColumn(name = "user_id")
private User user;
I'm just not sure how I can tell JPA/Hibernate not to touch the User whenever we delete the Survey.
It doesn't matter if I save the User with Survvey or not does it?
Basically I've tried a lot of options and I figure I'm not quite grasping the issue, and I suspect it's about the annotations on the User side, but I still feel as if I should be able to delete the child entity with no problem at all since I am not touching the parent entity?
This is because of EAGER fetch type in User class for surveys.
You delete survey but because it is existed on surveys set in user yet, it wouldn't be deleted actually.
You need to do like this:
// User class
#OneToMany(cascade=CascadeType.ALL, orphanRemoval=true, mappedBy="user")
private Set<Survey> surveys = new HashSet<>();
//Survey class
#ManyToOne
#JoinColumn(name = "user_id")
private User user;
I have SpringBoot 2.1.3 and Java 8 application. Building DB with JPA I have 3 table in one to one relationship. Suppose the tables is the follows:
#Entity
#Data //lombok
#Table(name = "users")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private Long id;
#OneToOne(mappedBy = "user", cascade = CascadeType.ALL)
private Address address;
}
And then:
#Entity
#Data
#Table(name = "address")
public class Address {
#Id
#Column(name = "id")
private Long id;
#OneToOne
#MapsId
private User user;
}
That's works.. and it is the best way to do (this exactly example is taken from documentation).
If I start the application the DB is created and if I tried to add entities all works well. The model created follows:
Now I want to add a Country object to my address Entities (for example) and I modified the Entities as follows:
#Entity
#Data
#Table(name = "address")
public class Address {
#Id
#Column(name = "id")
private Long id;
#OneToOne
#MapsId
private User user;
#OneToOne
#MapsId
private Country country;
}
And Country Entities:
#Entity
#Data
#Table(name = "country")
public class Country {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private Long id;
#OneToOne(mappedBy = "country", cascade = CascadeType.ALL)
private Address address;
}
The application still starts, the DB is created and the model follows:
But if I try to save a User as follows:
User user = new User();
Address address = new Address();
Country country = new Country();
user.setAddress(address);
address.setUser(user);
address.setCountry(country);
country.setAddress(address);
userRepository.save(user);
I obtain the error:
java.sql.SQLException: Field 'country_id' doesn't have a default value
Anyway I solve the issue removing #MapsId and added #JoinColumn but I would like to understand what's wrong.
P.S.: I'm using MySQL 5.7 with InnoDB dialect (setting on application.properties)
Thanks all
It works only with one #MapsId annotation. Using two is causing that country id is not inserted:
insert into Country (id) values (?)
insert into Users (id) values (?)
insert into Address (user_id) values (?)
I have two tables. I want to make between them relationship, but the thing is that the child table connects to an attribute in a parent node, which is not a PK. How can I assign a non-PK field as a FK for a table?
Here are the tables. User Information:
#Entity
#Table(name="user")
public class userinformation implements Serializable {
#Id
#GeneratedValue(strategy=GenerationType.IDENTITY)
#Column(name="USER_ID")
private int uID;
#Column(name="LIB_ID")
private String libID;
//Other attributes
}
Lib Information
#Entity
#Table(name="libinfo")
public class Auth {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name="AUTH_ID")
private int authID;
#Column(name="LIB_ID")
private String lib_ID;
//Other attributes
}
They both should be linked through libID (surely unique). Any idea how to implement it correctly?
Given:
class User {
#Column(name = "lib_id")
private String libID;
}
you must map the Auth entity as:
class Auth {
#JoinColumn(name = "lib_id", referencedColumnName = "lib_id")
#ManyToOne
private User user;
}
Basically, referencedColumnName is used to inform the JPA provider that it should use a column other than the primary key column of the referenced entity (which is used by default with #ManyToOne mappings).