I have entity structure:
#Entity
#Table(name = "users")
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id", updatable = false, nullable = false)
private Long id;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "user", cascade = { CascadeType.ALL })
List<UserAgreement> userAgreements= new ArrayList<>();
}
#Entity
#Table(name = "user_agreements")
public class UserAgreement {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id", updatable = false, nullable = false)
private Long id;
#ManyToOne(cascade = CascadeType.REFRESH)
#JoinColumn(name = "user_id")
private User user;
#ManyToOne(cascade = CascadeType.REFRESH)
#JoinColumn(name = "agreement_id")
private Agreement agreement;
}
#Entity
#Table(name = "agreements")
public class Agreement {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id", updatable = false, nullable = false)
private Long id;
#OneToMany(fetch = FetchType.LAZY, mappedBy = "agreement", cascade = { CascadeType.ALL })
List<UserAgreement> userAgreements = new ArrayList<>();
}
I am using Spring Boot with JpaRepository. When I use AgreementRepository extends JpaRepository<Agreement, Long> to save Agreement and related UserAgreement, it works well and cascades necessary fields to DB:
agreement.getUserAgreements().add(new UserAgreement(user, agreement, status));
agreementRepository.save(agreement);
However, after save, if try to retrieve user.getActiveUserAgreements(), I get empty list. It does not refresh.
How to force User entity to get List<UserAgreement> which was saved from other side?
From the Wikibooks: OneToMany
The relationship is bi-directional so, as the application updates one
side of the relationship, the other side should also get updated, and
be in sync. In JPA, as in Java in general it is the responsibility of
the application, or the object model to maintain relationships. If
your application adds to one side of a relationship, then it must add
to the other side.
That means you need to assign the UserAgreement to the User when you create the relation.
It looks like many-to-many association. You might probably drop UserAgreement class. Anyway, to support it you have to write helper methods addAgreement(), removeAgreement() etc. See more details here https://vladmihalcea.com/the-best-way-to-use-the-manytomany-annotation-with-jpa-and-hibernate/
Related
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
Let's se we have Hibernate entity User with basic fields such as username, password, roles etc..
Now we have an entity such as Car.
User has a OneToOne relationship with Car, cause he can own a car. But he also has besides this a OneToMany relationship to Car, because he also owns the cars of his children. But in the frontend I want to know which cars he owns for himself and which cars he owns for his children. The same applies to the relationship between User and motorbike (his own, his childrens, etc...)
How would the User entity class look like? Is it good to have the relationships mapped in an "Helper" entity such as UserData:
#Entity
#Data
#Table( name = "users",
uniqueConstraints = {
#UniqueConstraint(columnNames = "username")
})
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#NotBlank
#Size(max = 150)
private String username;
#NotBlank
#Size(max = 120)
private String password;
#OneToOne(cascade = {CascadeType.ALL}, fetch = FetchType.EAGER)
#JoinColumn(name = "USER_DATA_ID")
private UserData userData;
UserData:
#Entity
#Data
#Table( name = "user_data")
public class UserData {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Long id;
#OneToOne(cascade = {CascadeType.ALL}, fetch = FetchType.EAGER)
#JoinColumn(name = "OWN_CAR_ID")
private Car ownCar;
#OneToOne(cascade = {CascadeType.ALL}, fetch = FetchType.EAGER)
#JoinColumn(name = "PARTNER_CAR_ID")
private Car partnerCar;
#ManyToMany(fetch = FetchType.LAZY)
#JoinTable( name = "user_children_cars",
joinColumns = #JoinColumn(name = "user_data_id"),
inverseJoinColumns = #JoinColumn(name = "car_id"))
private Set<Car> childrenCars = new HashSet<>();
public boolean addToChildrenCarSet(Car c) {
return childrenCars.add(c);
}
public UserData() {
}
}
As you ask for an opinion, I would say it gets unnecessary complicated if you use the intermediate entity user_data. :-) There is no real drawback to add more fields and keys into the user class - performance is probably also better then using the EAGER fetching. If performance is an issue, better optimize querys later on then splitting the table now.
Also the #ManyToMany I would avoid - better create the intermediate table and relations yourself. You can check out https://bootify.io and create your database schema there. There is no EAGER fetching and also no CascadeType.ALL (both only good ideas in special cases), you would probably add more problems with that then actual helping in any way.
So the addToChildrenCarSet method would end up in a #Service class, in a method with #Transactional, in my proposal.
I have an app with Angular front end and Spring backend. The two classes in question here are (backend):
#Setter
#Getter
#AllArgsConstructor
#NoArgsConstructor
#Entity
#Table(name = "tournament_games")
#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "id")
public class TournamentGame {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
#Column(name = "id")
private Long id;
#ManyToOne(fetch = FetchType.EAGER, optional = false)
#JoinColumn(name = "code", foreignKey = #ForeignKey(name = "code_fk"))
private TournamentCode code;
#ManyToOne(fetch = FetchType.EAGER, optional = false)
#JoinColumn(name = "type", foreignKey = #ForeignKey(name = "game_type_fk"))
private GameType type;
#Column(name = "home_score")
private int home_score;
#Column(name = "away_score")
private int away_score;
#ManyToOne(fetch = FetchType.EAGER, optional = false)
#JoinColumn(name = "result_type", foreignKey = #ForeignKey(name = "result_type_fk"))
private ResultType result_type;
#Column(name = "status")
private boolean status;
#Column(name = "round")
private int round;
#Column(name = "locked")
private boolean locked;
#OneToMany(mappedBy = "game", fetch = FetchType.EAGER)
private List<TournamentGamesPlayers> players = new ArrayList<>();
}
and
#Setter
#Getter
#AllArgsConstructor
#NoArgsConstructor
#Entity
#Table(name = "tournament_games_players")
#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class, property = "game")
public class TournamentGamesPlayers implements Serializable {
private static final long serialVersionUID = 1L;
#Id
#ManyToOne
#JoinColumn(name = "tournament_game_id")
private TournamentGame game;
#Id
#ManyToOne
#JoinColumn(name = "playerid")
private Player player;
#Column(name = "home")
private boolean home;
}
I need help figuring out how to persist the List<TournamentGamesPlayers> when I save and/or update a TournamentGame object. I generate 45 games. The first 30 games have known players, and so I set them before saving. The last 15 do not have entries for the TournamentGamesPlayers join table, because I need to add them later.
I am able to get some results with CascadeType.ALL on the #OneToMany side when I initially generate the games, but it fails when I try to update a game with a seemingly infinite recursion/stack overflow.
If I omit any cascade type, the games side get generated, but the join table #ManyToOne side does not get entered.
I ended up just putting the players back into the game table to make my life easier.
try putting CascadeType.MERGE, CascadeType.ALL "delete parent and orphans" (JPA CascadeType.ALL does not delete orphans).
Also, defining the relationship as EAGER and not ignoring the JSON property can have problems. I would add #JsonIgnore to one of the parts of the relationship
I have a model that looks like this:
#Entity
#Table(name = "A")
class A {
#ManyToMany(fetch = FetchType.LAZY, cascade = CascadeType.ALL)
#JoinTable(name = "A_categories", joinColumns = {
#JoinColumn(name = "A_id", nullable = false, updatable = false) },
inverseJoinColumns = { #JoinColumn(name = "category_id",
nullable = false, updatable = false) })
private List<Category> categories;
}
#Entity
#Table(name = "category")
class Category {
#Id
#Column(name="id")
#GeneratedValue
private Integer id;
#Column(name = "category_name")
private String categoryName;
#ManyToMany(fetch = FetchType.LAZY, mappedBy = "categories")
private List<A> a;
}
So there is a many-to-many relationship between A and Category. Now categories are static, and cannot be changed by a user. From the UI, the user will try to save an entity A, and each can have one or more categories. So the JSON that comes back looks a little like this:
{A: {categories: [{id: 1}, {id: 2}, {id: 3}]}}
Now when I try to save this A object (after jackson has unmarshalled to java), I just want entries to be made in the join table, A_categories, for each category the new entity has.
However, the Category entity itself also gets updated. So if you notice, the JSON does not have any category_name, and so the database entry for each Category will also get updated to a null entry for the name.
How can I prevent this from happening?
Two different approaches:
1) Set managed categories before merging.
a.setCategories(readAllByIds(a.getCategories()))
private Collection<Category> readAllByIds(Collection<Category> categories) {
Collection<Category> result = new ArrayList();
for (Category category : categories) {
result.add(entityManager.getReference(Category.class, category.getId()));
}
return result;
}
EntityManager.getReference returns proxy, so the additional benefit is that no database round trips are executed for reading the associated categories.
With this solution you are not merging the deserialized categories into the persistence context, thus Hibernate will not synchronize their state with the database.
2) Do not cascade any operations from A to categories (remove cascade attribute).
This way, neither PERSIST nor MERGE will be cascaded and Hibernate will just use ids of the detached Category instances to store the data into the relationship table.
Sidenote: Generally, cascading REMOVE or ALL in a many-to-many association makes no sense (if you remove an A you probably don't want to remove all the categories it belongs to).
#Column has the attributes insertable and updatable. You can set them to false:
#Entity
#Table(name = "category")
class Category {
#Id
#Column(name="id", insertable=false, updatable=false)
#GeneratedValue
private Integer id;
#Column(name = "category_name", insertable=false, updatable=false)
private String categoryName;
#ManyToMany(fetch = FetchType.LAZY, mappedBy = "categories")
private List<A> a;
}
You can try adding this
#Entity
#Table(name = "category")
class Category {
#Id
#Column(name="id")
#GeneratedValue
private Integer id;
#Column(name = "category_name")
private String categoryName;
#ManyToMany(fetch = FetchType.LAZY, mappedBy = "categories", cascade=CascadeType.DETACH)
private List<A> a;
}
with the cascade.DETACH should not save changes when you save A entity, but let me know if is not working to make an example modifying the ManyToMany relationship with this DETACH action
I have an entity who own many object
#Entity
public class Lodger implements Serializable {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long lodgerId;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "lodger")
private List<IdentityCard> identityCardList;
#OneToMany(cascade = CascadeType.ALL, fetch = FetchType.EAGER, mappedBy = "lodger")
private List<Phone> phoneList;
...
}
#Entity
public class IdentityCard {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
private Long identityCardId;
private String identyCardValue;
#OneToOne
#JoinColumn(name = "identity_card_type_id") //without -> identity_card_type_identityCardTypeId
private IdentityCardType identityCardType;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "lodger_id")
private Lodger lodger;
}
When i save my lodger, all my object is saved (identiyCard, phone), but their field lodger_id is null.
I was thinking it was supposed to be done automatically when we use cascadeType.all.
The owner side of the bi-directioinal associations are in IdentityCard and Phone entities, this is the same as saying that the mappedBy is in Lodger's associations.
So for the persistence of the links you must set the lodger attribute in IdentityCard and Phone entities. Isn't necessary to add this entities to the Lodger's collections but it is fine because you want to save this entities along with Lodger using cascade option.