I am getting null when using relationship in hibernate.
Here is my code
User entity
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.AUTO)
private long userId;
#OneToMany(mappedBy="user",targetEntity=LoginHistory.class, fetch=FetchType.LAZY,cascade = CascadeType.ALL)
private List<LoginHistory> loginHistory = new ArrayList<LoginHistory>();
LoginHistory Entity
#Entity
#Table(name = "login_history")
public class LoginHistory {
#Id
#Column(name = "id")
#GeneratedValue(strategy = GenerationType.IDENTITY)
private long id;
#ManyToOne(cascade = CascadeType.DETACH)
#JoinColumn(name="userId",referencedColumnName="id")
private User user;
To get login history details
#Override
public List<LoginHistory> getLoginHistory(User user) {
List<LoginHistory> lst = user.getLoginHistory();
return lst;
}
I am getting an empty list. Please help
it is working as designed as you are accessing an entity which is lazy loaded.Use the below like code to get the login history if you continue to keep the lazy loading on.
User user = getByKey(id);
if(user!=null){
Hibernate.initialize(user.getUserProfiles());
}
Related
I'm using Spring JPA and MySQL as the database. I have trouble with self-referencing its own entity.
I know the code below would do self-referencing, but it actually creates a new table to do so.
#Getter
#Entity
#NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Member extends BaseTimeEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "member_id")
private Long id;
#ManyToMany
#JoinColumn(name = "followings_id")
private List<Member> followings = new ArrayList<Member>();
#ManyToMany
#JoinColumn(name = "followers_id")
private List<Member> followers = new ArrayList<Member>();
#ManyToMany
#JoinColumn(name = "blocked_id")
private List<Member> blocked = new ArrayList<Member>();
...
}
Question: I'm wondering if I can do this in a single table(which would be the member table) without creating a new table to do many-to-many self-referencing.
It is possible,
Instead of using the #ManyToMany annotation, you can use the #OneToMany and #ManyToOne annotations to create the self-referencing relationship
#Getter
#Entity
#NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Member extends BaseTimeEntity {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "member_id")
private Long id;
#OneToMany(mappedBy = "follower")
private List<Follow> followings = new ArrayList<>();
#OneToMany(mappedBy = "following")
private List<Follow> followers = new ArrayList<>();
#OneToMany(mappedBy = "blocker")
private List<Block> blocked = new ArrayList<>();
}
#Entity
#Getter
#NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Follow {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToOne
#JoinColumn(name = "follower_id")
private Member follower;
#ManyToOne
#JoinColumn(name = "following_id")
private Member following;
}
#Entity
#Getter
#NoArgsConstructor(access = AccessLevel.PROTECTED)
public class Block {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#ManyToOne
#JoinColumn(name = "blocker_id")
private Member blocker;
#ManyToOne
#JoinColumn(name = "blocked_id")
private Member blocked;
}
Now Follow and Block entities represent the many-to-many relationships between Member entities and follower and following properties in the Follow entity represent the two sides of the many-to-many relationship, and the same is for blocked and blocker.
I have two table user(id,name) and user_mails(id,email,user_id) user to user_mails have one to many relation.
I have created following entity in spring boot
User
#Entity
#Table(name = "user")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
private int id;
#Column(name = "name", nullable = false)
private String name;
#OneToMany(mappedBy = "user", cascade = CascadeType.ALL)
private Set<UserMail> userMails =new HashSet<UserMail>(0);
//Getter setter and constructor
}
UserMail
#Entity
#Table(name = "user_mails")
public class UserMail {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private int id;
#Column(name = "email", nullable = false)
private String name;
#ManyToOne(fetch = FetchType.LAZY, optional = false)
#JoinColumn(name = "user_id")
private User user;
It is showing following output on calling controller
[{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":[{"id":2,"name":"ram#b.com","user":{"id":1,"name":"Ram","userMails":
and more
I want to access all users with all mail ids also want to acces mail id with user details
What changes should I do to get proper result
I have two entities in one to many relationship in my spring-data-jpa project.
Parent entity -
#Entity
#Table(name = "code_group")
public class CodeGroup implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE)
private Long id;
#NaturalId
#Column(nullable = false)
private String entityId;
#OneToMany
#JoinColumn(name = "codeGroupId", referencedColumnName = "entityId")
private List<SystemCode> systemCodes;
// .. getters setters
}
Child entity -
#Entity
#Table(name = "system_code")
public class SystemCode implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#GeneratedValue(strategy = GenerationType.SEQUENCE)
private Long id;
#Column(nullable = false)
private String codeGroupId;
#Column(nullable = false)
#Enumerated(EnumType.STRING)
private ActiveOrInactive status;
// getters and setters
}
status column is of enum type, it can only have Active or Inactive value.
My existing code works fine. It is fetching code group with associated system codes. I want to filter system code with status='Active'. How to do this?
Try like this:
#OneToMany
#JoinColumn(name = "codeGroupId", referencedColumnName = "entityId")
#Where(clause = "status= 'Active'")
private List<SystemCode> systemCodes;
You can create such methods in your repo:
List<CodeGroup> getAllBySystemCodes_Status(ActiveOrInactive status);
default List<CodeGroup> getAllActive() {
return getAllBySystemCodes_Status(ActiveOrInactive.Active);
}
default List<CodeGroup> getAllInactive() {
return getAllBySystemCodes_Status(ActiveOrInactive.Inactive);
}
I have many to many relation between User and Event. I need to have extra column in relational table. I did id:
#Entity
public class User {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private long id;
#OneToMany(mappedBy="user")
private Set<EventUser> eventUsers = new HashSet<>();
//
}
#Entity
public class Event {
#Id
#GeneratedValue(strategy= GenerationType.AUTO)
private long id;
#OneToMany(mappedBy="event")
private Set<EventUser> eventUsers = new HashSet<>();
//
}
#Entity
#Table(name = "Event_User")
public class EventUser {
#Id
#GeneratedValue(strategy= GenerationType.AUTO)
private long id;
private String reaction;
#ManyToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "user_id")
private User user;
#ManyToOne(cascade = CascadeType.ALL)
#JoinColumn(name = "event_id")
private Event event;
//
}
But now... I don't know how to load all events where user has concrete email. Before it I used method:
findByUsersEmail(String email);
Now I can't do this, because Event doesn't have Set users field.
Any ideas ?
What you need here is property-expressions.
Just a quick idea to start:
findByEventUsers_UserEmail(String email);
Note: Dont forget that creating queries by method names is a very limited approach and only used by trivial cases. In any other case, don't be afraid of using the #Query annotation on the method or write JPQL/Criteria API manually.
I have an unidirectional OneToMany JPA entity mapping in my (Spring Framework + Spring Data + Hibernate JPA) project. Entity classes are like in the following code.(I have removed irrelevant class members for brevity).
#Entity
#Table(name = "employees")
class Employee{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Integer id;
#OneToMany(cascade = CascadeType.ALL, orphanRemoval = true)
#JoinColumn(name = "employee_id")
private List<DepartmentAssignment> departmentAssignments = new ArrayList<>();
}
#Entity
#Table(name = "department_assignments")
class DepartmentAssignment{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Integer id;
#NotNull
#Column(name = "employee_id")
private Integer employeeId;
#NotNull
#Column(name = "department_id")
private Integer departmentId;
}
#Entity
#Table(name = "departments")
class Department{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Integer id;
}
And, in one of my service classes have a method to remove a DepartmentAssignment from an Employee like below.
public Employee deleteDepartmentAssignment(Integer empId, Integer deptAssignmentId) {
Employee employee = employeeRepository.findOne(empId);
if(employee != null) {
for ( DepartmentAssignment da : employee.getDepartmentAssignments()) {
if(da.getId().equals(deptAssignmentId)) {
employee.getDepartmentAssignments().remove(da);
employee = employeeRepository.save(employee);
break;
}
}
}
return employee;
}
However, calling above methods gives me an error: org.hibernate.exception.ConstraintViolationException ,and in the SQL log, I can see Column 'employee_id' cannot be null error for the last SQL statement of the transaction.
Can anybody tell me what I'm doing wrong here and how to get it fixed?
You don't need to add
#NotNull
#Column(name = "employee_id")
private Integer employeeId;
to the Employee, if you use #JoinColumn(name = "employee_id"). Try to remove it.
You can try the following, not sure why you use the plain id in the object. Thats not object relational mapping.
For more details see Hibernate triggering constraint violations using orphanRemoval
#Entity
#Table(name = "employees")
class Employee{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#OneToMany(cascade = CascadeType.ALL, mappedBy = "employee", orphanRemoval = true)
private List<DepartmentAssignment> departmentAssignments = new ArrayList<>();
}
#Entity
#Table(name = "department_assignments")
class DepartmentAssignment{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
#ManyToOne(optional=false)
private Employee employee;
#ManyToOne(optional=false)
private Department department;
}
#Entity
#Table(name = "departments")
class Department{
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Integer id;
}
You must look .hbm.xml file and you should mapping your Entity in this file and
you can look this example
http://www.mkyong.com/hibernate/hibernate-one-to-many-relationship-example/
I hope it will be useful for you.
try removing
cascade = CascadeType.ALL
but im not 100% sure..