Spring Data rest how to perform CRUD on @manytomany relation ,composite table with extra column

Question

I am unable to perform CRUD via json POST from restful client Postman on Composite table having extra column .I am using Spring boot ,spring data rest and spring JPA. I have 3 tables in data base
-user
-competency
-user_competency (join/composite table with extra column)

Here are my classes

User

@Entity
@Table(name = "\"user\"", schema = "public")
@JsonIdentityInfo(
          generator = ObjectIdGenerators.IntSequenceGenerator.class, 
          property = "userId")
public class User implements java.io.Serializable {

    private Long userId;

    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)

    @Column(name = "user_id", unique = true, nullable = false)
    public Long getUserId() {
        return this.userId;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }

    private Set<UserCompetency> userCompetencies = new HashSet<UserCompetency>(0);

        @OneToMany(fetch = FetchType.EAGER,cascade = {CascadeType.ALL}, mappedBy = "user")
    public Set<UserCompetency> getUserCompetencies() {
        return this.userCompetencies;
    }

    public void setUserCompetencies(Set<UserCompetency> userCompetencies) {
        this.userCompetencies = userCompetencies;
    }

}

Competency

@Entity
@Table(name = "competency", schema = "public")
@JsonIdentityInfo(
          generator = ObjectIdGenerators.IntSequenceGenerator.class, 
          property = "competencyId")
public class Competency implements java.io.Serializable {


    private Long competencyId;
    private Set<UserCompetency> userCompetencies = new HashSet<UserCompetency>(0);

    @Id @GeneratedValue(strategy = GenerationType.IDENTITY)

    @Column(name = "competency_id", unique = true, nullable = false)
    public Long getCompetencyId() {
        return this.competencyId;
    }

    public void setCompetencyId(Long competencyId) {
        this.competencyId = competencyId;
    }

        @OneToMany(fetch = FetchType.LAZY, mappedBy = "competency")
    public Set<UserCompetency> getUserCompetencies() {
        return this.userCompetencies;
    }

    public void setUserCompetencies(Set<UserCompetency> userCompetencies) {
        this.userCompetencies = userCompetencies;
    }
}   

UserCompetency

@Entity
@Table(name = "user_competency", schema = "public")
@JsonIdentityInfo(
          generator =ObjectIdGenerators.IntSequenceGenerator.class, 
          property = "id")
public class UserCompetency implements java.io.Serializable {
    private UserCompetencyId id;
    private Level level;
    private User user;
    private Competency competency;

    @EmbeddedId

    @AttributeOverrides({
            @AttributeOverride(name = "competencyId", column = @Column(name = "competency_id", nullable = false)),
            @AttributeOverride(name = "userId", column = @Column(name = "user_id", nullable = false)) })
    public UserCompetencyId getId() {
        return this.id;
    }

    public void setId(UserCompetencyId id) {
        this.id = id;
    }

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "level_id")
    public Level getLevel() {
        return this.level;
    }

    public void setLevel(Level level) {
        this.level = level;
    }

    @ManyToOne(fetch = FetchType.EAGER)
    @JoinColumn(name = "user_id", nullable = false, insertable = false, updatable = false)
    public User getUser() {
        return this.user;
    }

    public void setUser(User user) {
        this.user = user;
    }

    @ManyToOne(fetch = FetchType.EAGER,cascade=CascadeType.ALL)
    @JoinColumn(name = "competency_id", nullable = false, insertable = false, updatable = false)
    public Competency getCompetency() {
        return this.competency;
    }

    public void setCompetency(Competency competency) {
        this.competency = competency;
    }
}   

UserCompetencyId

@Embeddable
public class UserCompetencyId implements java.io.Serializable {

    private Long competencyId;
    private Long userId;

    public UserCompetencyId() {
    }

    public UserCompetencyId(Long competencyId, Long userId) {
        this.competencyId = competencyId;
        this.userId = userId;
    }


    @Column(name = "competency_id", nullable = false)
    public Long getCompetencyId() {
        return this.competencyId;
    }

    public void setCompetencyId(Long competencyId) {
        this.competencyId = competencyId;
    }

    @Column(name = "user_id", nullable = false)
    public Long getUserId() {
        return this.userId;
    }

    public void setUserId(Long userId) {
        this.userId = userId;
    }

    public boolean equals(Object other) {
        if ((this == other))
            return true;
        if ((other == null))
            return false;
        if (!(other instanceof UserCompetencyId))
            return false;
        UserCompetencyId castOther = (UserCompetencyId) other;

        return (this.getCompetencyId() == castOther.getCompetencyId()) && (this.getUserId() == castOther.getUserId());
    }    
}

Suppose i have already record in User and Competency tables and i want to assocaite both i am trying to post like this ,but it give me error of 405 Method Not Allowed.

help required ,what should be structure of json to be posted User will already exist and competency will might exist or new can be added and associated with existing user.

Answer 1

With this code I was able to post a new relation:

UserCompetency.class

@Entity
@Table(name = "user_competency")
@IdClass(UserCompetencyId.class)
public class UserCompetency implements java.io.Serializable {

    @Id @ManyToOne
    @JoinColumn(name = "competency_id", nullable = false, insertable = false, updatable = false)
    private Competency competency;

    @Id @ManyToOne
    @JoinColumn(name = "user_id", nullable = false, insertable = false, updatable = false)
    private User user;

UserCompetencyId.class

public class UserCompetencyId implements java.io.Serializable {

    private Long competency;

    private Long user;

    public UserCompetencyId() {
    }

    public UserCompetencyId(Long competency, Long user) {
        this.competency = competency;
        this.user = user;
    }

UserCompetencyRepository.class

public interface UserCompetencyRepository extends JpaRepository<UserCompetency, UserCompetencyId> {

}

POST http://localhost:8080/userCompetencies

{
    "competency": "/competencies/2"
    , "user": "/user/4"
}

Answer 2

Apparently there seems to be no "natural/easy" way to get what you want. But there is a promissing project for integrating embeddables by extending the serialization process: https://github.com/gregturn/embeddable-spring-data-rest

• UserCompetencyIdJacksonModule, UserCompetencyIdSerializer, ..

Then you should be able PATCH (not POST) your JSON from above.