Using a Spring Entity inside another Spring Entity

Question

Getting the following error when I try to add a "Game" object to my ArrayList specified in my User class. This action was done in my controller class:

"org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: com.billsheng.huddlespringmvc.models.Game; nested exception is java.lang.IllegalStateException: org.hibernate.TransientObjectException: object references an unsaved transient instance - save the transient instance before flushing: com.billsheng.huddlespringmvc.models.Game"

User Entity

@Data
@Entity
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;

    private String email;
    private String firstName;
    private String lastName;
    private String password;
    private String chosenTeam;
    private int gamesPlayed;
    private int gamesWon;

    @ElementCollection
    private List<Game> games = new ArrayList<>();

    public User(String firstName, String lastName, String email, String password, String chosenTeam, int gamesPlayed, int gamesWon, ArrayList<Game> games) {
        this.firstName = firstName;
        this.lastName = lastName;
        this.email = email;
        this.password = password;
        this.chosenTeam = chosenTeam;
        this.gamesPlayed = gamesPlayed;
        this.gamesWon = gamesWon;
        this.games = games;
    }

    public User(String firstName, String lastName, String email, String password, String chosenTeam) {
        this(firstName, lastName, email, password, chosenTeam, 0, 0, null);
    }

    public User(int gamesPlayed, int gamesWon, ArrayList<Game> games) {
        this.gamesPlayed = gamesPlayed;
        this.gamesWon = gamesWon;
        this.games = games;
    }

    public User() {
    }

//getters and setters
}

Game Entity

@Data
@Entity
public class Game {
    @Id
    @GeneratedValue(strategy = GenerationType.AUTO)
    private Integer id;
    private String homeTeam;
    private String awayTeam;
    private Date date;
    private String location;
    private String bettingOdds;
    private boolean inProgress;
    private boolean isReviewed;

//getters and setters
}

I did some research and I believe this issue stems from me using my Game object inside my User object but I'm not sure what the problem is specifically. All help is appreciated.

Have you tried to map the collection with `@OneToMany` and configure the cascade? — nortontgueno, Mar 19 '19 at 00:08
thanks, i tried to map @OneToMany and I got the same error. What do you mean by "configure the cascade" — Bill Sheng, Mar 19 '19 at 00:13
[Cascade thread](https://stackoverflow.com/questions/3667387/what-is-the-difference-between-cascade-inverse-in-hibernate-what-are-they-use) and a [good reading](https://vladmihalcea.com/the-best-way-to-map-a-onetomany-association-with-jpa-and-hibernate/) for mapping — nortontgueno, Mar 19 '19 at 00:17
This isn't a Spring thing; `@Entity` is about JPA. Spring provides help for using JPA features, but this is entirely JPA. Regarding ngueno's comment, read the documentation for the `cascade` attribute on `@OneToMany`. — chrylis -cautiouslyoptimistic-, Mar 19 '19 at 00:21
Oops, yeah I'm new to Java api development. Thanks for the help guys. The following annotation worked: `@OneToMany(cascade = CascadeType.ALL)` — Bill Sheng, Mar 19 '19 at 00:24

score 0 · Answer 1 · answered Mar 19 '19 at 17:27

@ElementCollection is not supposed to be used with collections of entities; it's used with collections of @Embeddable. If Thing is an entity, you don't use @ElementCollection, you use @OneToMany.

@ElementCollection: Defines a collection of instances of a basic type or embeddable class

You can use @OneToMany mapping for establishing the relationship between User and Game entity.

User.java

@OneToMany(cascade=CascadeType.ALL,fetch= FetchType.LAZY,mappedBy = "user")
private List<Game> games = new ArrayList<>();

//getters and setters

Game.java

@ManyToOne
private User user;

//getters and setters

Using a Spring Entity inside another Spring Entity

1 Answers1