JPA ManyToMany Relationship Hibernate

Question

I have a Entity Movie and then Person Entity. Movie has a ManyToMany relationship with Person: one by casting, another by production and another by directio.

So my question is given a Person how I can obtain the movies he has acted, produced and directed.

//Person class:

@Entity
public class Person implements Serializable{

private static final long serialVersionUID = 1L;

@Id
@JsonView(Views.Private.class)
@GeneratedValue(strategy = GenerationType.IDENTITY)
private Long idPerson;
private String name;
private String surnames;
private boolean isActor;
private boolean isDirector;
private boolean isProducer;

@ManyToMany(mappedBy = "casting")
private Set<Movie> moviesCasting = new HashSet<>();

@ManyToMany(mappedBy = "movieDirection")
private Set<Movie> movieDirection = new HashSet<>();

@ManyToMany(mappedBy = "movieProduction")
private Set<Movie> movieProduction = new HashSet<>();

//Movie class

 @Entity
 public class Movie implements Serializable {

private static final long serialVersionUID = 1L;    
@ManyToMany(cascade = {CascadeType.ALL})
@JoinTable(name = "casting_movie",
        joinColumns = @JoinColumn(name = "id"),
        inverseJoinColumns = @JoinColumn(name = "idPerson")
)
private Set<Person> casting = new HashSet<>();

public Set<Person> getCasting() {
    casting.size();
    return casting;
}

@ManyToMany(cascade = {CascadeType.ALL})
@JoinTable(name = "production_movie",
        joinColumns = @JoinColumn(name = "id"),
        inverseJoinColumns = @JoinColumn(name = "idPerson")
)
private Set<Person> movieProduction = new HashSet<>();

public Set<Person> getMovieProduction() {
    movieProduction.size();
    return movieProduction;
}

@ManyToMany(cascade = {CascadeType.ALL})
@JoinTable(name = "direction_movie",
        joinColumns = @JoinColumn(name = "id"),
        inverseJoinColumns = @JoinColumn(name = "idPerson")
)

private Set<Person> movieDirection = new HashSet<>();
getters and setters(...)

When I want to obtain information about a Person I get the error: failed to lazily initialize a collection of role Movies.casting”

If I given a Person I want to obtain each "filmography" I have to create the ManyToMany Relationship bidirectional?

Answer 1

You can have another entity which will have many-to-one references to Movie and Person with one additional field RelationshipType (with values Casting, Production, Direction etc). You should create a enum for that.

By doing so, you can fetch a person's directed movies like (from new entity): findByMovieAndPersonAndRelationshipType(Movie movie, Person person, RelationshipType.DIRECTED);

PS get rid of your all many-to-many relationships