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hubman
Asked: 2020-05-03 11:49:11 +0800 CST 2020-05-03 11:49:11 +0800 CST

I get this error on post request: table not found

  • 772

I want to relate friends of users, the problem I have is how to get the friends of a user? I think part of my problem is that I am putting the list of friends as an attribute in the User class, private Set<User> friends = new HashSet<>(); is that ok?

I am putting this json through swagger, since they are existing users in the database.

{
  "friend": {
    "email": "string",
    "friends": [],
    "id": 0,
    "name": "string",
    "password": "string"
  },
  "owner": {
    "email": "wwww",
    "friends": [],
    "id": 3,
    "name": "dsadsa",
    "password": "d"
  }
}

This is my controller, where everything starts:

@PostMapping("/addFriend")
    public ResponseEntity<User> getUser(@RequestBody Friendship friendship) {
        log.info("addFriend");
        return new ResponseEntity<User>(userServiceImpl.createLinkWithFriends(friendship), HttpStatus.OK);
    }

This is the service:

public User createLinkWithFriends(Friendship friendship) {
    User owner=userRepository.findById(friendship.getOwner().getId());
    User friend=userRepository.findById(friendship.getFriend().getId());
    owner.addFriend(friend);

    friendsRepository.save(friendship);
    return owner;
}

and this is the repository User

@Entity
@Table(name = "user")
public class User implements Serializable {

    private static final long serialVersionUID = -3009157732242241606L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long id;

    @Column(name = "name")
    private String name;

    @Column(name = "password")
    private String password;

    @Column(name = "email")
    private String email;

    @OneToMany(fetch=FetchType.EAGER)
    @JoinTable(
            name = "Friendship",
            joinColumns = @JoinColumn(name = "id"),
            inverseJoinColumns = @JoinColumn(name = "idFriend"))
    private Set<User> friends = new HashSet<>();

    public User() {

    }

    public User(String name, long id, String password, String email) {
        this.email = email;
        this.name = name;
        this.id = id;
        this.password = password;
    }

    public void addFriend(User userFriend){
        this.friends.add(userFriend);
    }

This is the Friendship class

@Entity
@Table(name = "Friendship")
public class Friendship implements Serializable {

    private static final long serialVersionUID = -3009157732242241606L;
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private long idFriend;

    @ManyToOne
    private User owner;

    @ManyToOne
    private User friend;

    public Friendship() {

    }

    public User getOwner() {
        return owner;
    }

    public void setOwner(User owner) {
        this.owner = owner;
    }

    public User getFriend() {
        return friend;
    }

    public void setFriend(User friend) {
        this.friend = friend;
    }
}

i get this error when i do mvn clean package

2019-05-03 23:54:59.925  INFO 20200 --- [           main] org.hibernate.Version                    : HHH000412: Hibernate Core {5.0.12.Final}
2019-05-03 23:54:59.925  INFO 20200 --- [           main] org.hibernate.cfg.Environment            : HHH000206: hibernate.properties not found
2019-05-03 23:54:59.931  INFO 20200 --- [           main] org.hibernate.cfg.Environment            : HHH000021: Bytecode provider name : javassist
2019-05-03 23:54:59.979  INFO 20200 --- [           main] o.hibernate.annotations.common.Version   : HCANN000001: Hibernate Commons Annotations {5.0.1.Final}
2019-05-03 23:55:00.132  INFO 20200 --- [           main] org.hibernate.dialect.Dialect            : HHH000400: Using dialect: org.hibernate.dialect.H2Dialect
2019-05-03 23:55:01.094  INFO 20200 --- [           main] org.hibernate.tool.hbm2ddl.SchemaUpdate  : HHH000228: Running hbm2ddl schema update
2019-05-03 23:55:01.132  INFO 20200 --- [           main] rmationExtractorJdbcDatabaseMetaDataImpl : HHH000262: Table not found: friendship
2019-05-03 23:55:01.133  INFO 20200 --- [           main] rmationExtractorJdbcDatabaseMetaDataImpl : HHH000262: Table not found: friendship
2019-05-03 23:55:01.136  WARN 20200 --- [           main] o.s.w.c.s.GenericWebApplicationContext   : Exception encountered during context initialization - cancelling refresh attempt: org.sp
ringframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/Hibern
ateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate SessionFac
tory
2019-05-03 23:55:01.152  INFO 20200 --- [           main] utoConfigurationReportLoggingInitializer :

Error starting ApplicationContext. To display the auto-configuration report re-run your application with 'debug' enabled.
2019-05-03 23:55:01.184 ERROR 20200 --- [           main] o.s.boot.SpringApplication               : Application startup failed

org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'entityManagerFactory' defined in class path resource [org/springframework/boot/autoconfigure/orm/jpa/
HibernateJpaAutoConfiguration.class]: Invocation of init method failed; nested exception is javax.persistence.PersistenceException: [PersistenceUnit: default] Unable to build Hibernate Sess
ionFactory

I uploaded my project to github https://github.com/hubmanS/traslateInClick , I would really appreciate if you do the test

java

1 Answers

  1. Best Answer

    Regarding the error:detached entity passed to persist: com.example.demo.model.User

    And based on:at com.example.demo.service.UserServiceImpl.createLinkWithFriends(UserServiceImpl.java:42)

    It seems to me that the problem is that you are saving friendshipas it came by parameter, and from what you see the objects that make it up are not from the persistence context but rather what has been deserialized in the controller sent by the user.

    It seems to me that the error can be corrected by replacing the friendship objects with the corresponding entities lifted from the repositories or better by creating a new instance to ensure that the friendship does not have a preset id.

    Finally I get a new instance of the Userentity ownerfrom the repository to return the result at the end of the method. This way I make sure that the collection is made up of the persisted entities. (The latter may not be necessary)

    public User createLinkWithFriends(Friendship friendship) {
    User owner=userRepository.findById(friendship.getOwner().getId());
    User friend=userRepository.findById(friendship.getFriend().getId());
    Frienship newFriendship = new FriendShip();
    newFriendship.setOwner(owner);
    newFriendship.setFriend(friend);

    newFriendship = friendsRepository.save(newFriendship);

    owner = userRepository.findById(owner.getId());
    return owner;
}

    EDITION I:

    I put together a system mimicking the classes you have set up and modified it to make it work. There are probably other decisions I could have made that would make the solution different, i.e. this is one solution but not the only one:

    Apart from the change explained in the first answer, I changed the mappings and that change affected other modifications.

    The database model you use as having a reference

    User Class

    1. The most important change is that the OneToMany goes to Friendship and not to User.
    2. The `friends` set of `Friendship` maps to the `owner` attribute of the `Friendship` class. All `Friendship`s with the same `owner` are the friendships of the `User`.
    3. I was able to leave the fetch as `LAZY` instead of `EAGER` which avoids raising friends of friends of friends....
    4. `@JsonBackReference` is to avoid loops in serialization to Json (A friend of B friend of C friend of A friend of B friend of C ....).
    @OneToMany(fetch=FetchType.LAZY, mappedBy="owner")
@JsonBackReference 
private Set<Friendship> friends = new HashSet<>();

    On a personal note, I'd consider removing the collection from friendsalong with the mapping, to deal directly with the entity Friendship.

    Friendship class

    1. In the OneToMany I added the join columns to identify the correct column of the table that is the foreign key to the User table
    2. The `MapsId` that was originally there would be used in the case of an `EmbeddedId`, which would be another way of assembling the solution
    @ManyToOne
@JoinColumn(name="owner") // Campo de la tabla friendship que es fk de User
@JsonManagedReference
private User owner;

@ManyToOne
@JoinColumn(name="friend") // Campo de la tabla friendship que es fk de User
private User friend;

    Controller

    In the controller, as Json serialization limited the addition of the friends collection, I added one more endpoint to retrieve a user's friends. The methods are modified to receive form parameters instead of json objects, but this doesn't change the essence.

    @PostMapping("/addFriend")
public ResponseEntity<User> getUser(@RequestParam("owner") Long ownerId, @RequestParam("friend") Long friendId) {
    return new ResponseEntity<User>(userService.createLinkWithFriends(ownerId, friendId), HttpStatus.OK);
}

@GetMapping("/owner/{id}/friends")
public ResponseEntity<List<User>> getFriendsOf(@PathVariable("id") Long ownerId) {
    return new ResponseEntity<List<User>>(userService.getFriendsOf(ownerId), HttpStatus.OK);
}

    Services

    The same as the first answer plus a method to search for friends.

    @Override
@Transactional
public User createLinkWithFriends(Long ownerId, Long friendId) {
    User owner = userRepository.findById(ownerId).orElse(null);
    User friend = userRepository.findById(friendId).orElse(null);

    if(owner == null) throw new RuntimeException("Owner not found");
    if(friend == null) throw new RuntimeException("Friend not found");

    Friendship newFriendship = new Friendship();
    newFriendship.setOwner(owner);
    newFriendship.setFriend(friend);

    newFriendship = friendshipRepository.save(newFriendship);   
    owner = userRepository.findById(owner.getId()).orElse(null);    
    return owner;
}

@Override
public List<User> getFriendsOf(Long ownerId) {
    List<User> rtn = new ArrayList<>();
    User user = userRepository.findById(ownerId).orElse(null);
    if(user!=null) {
        for(Friendship fsh : user.getFriends()) {
            rtn.add(fsh.getFriend());
        }
        return rtn;
    }
    return null;
}
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