Relationships with JPA

UML

Unidirectional OneToOne UML relationship

Kukulkan Grammar

    entity Left {
        OneToOne attRight: Right
    }
    entity Right {}

Data Model

Unidirectional OneToOne Data Model

Foreign Keys:

From lefts table to rights table: fk_lefts.att_right_id_rights.id

Java (POJO)

    @Entity
    @Table(name = "lefts")
    public class Left implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @OneToOne
        @JoinColumn(name = "att_right_id", unique = true)
        private Right attRight;

        public Long getId() {
            return id;
        }

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

        public Right getAttRight() {
            return attRight;
        }

        public void setAttRight(Right attRight) {
            this.attRight = attRight;
        }

    }

    @Entity
    @Table(name = "rights")
    public class Right implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        public Long getId() {
            return id;
        }

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

    }

UML

Unidirectional OneToMany UML relationship

Unsupported!

The Left entity must always be navigable from Right entity.

This case will be the same as Bidirectional OneToMany

UML

Unidirectional ManyToOne UML relationship

Kukulkan Grammar

    entity Left {
        ManyToOne attRight: Right
    }
    entity Right {}

Data Model

Unidirectional ManyToOne Data Model

Foreign Keys:

From lefts table to rights table: fk_lefts.att_right_id_rights.id

Java (POJO)

    @Entity
    @Table(name = "lefts")
    public class Left implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @ManyToOne
        @JoinColumn(name = "att_right_id")
        private Right attRight;

        public Long getId() {
            return id;
        }

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

        public Right getAttRight() {
            return attRight;
        }

        public void setAttRight(Right attRight) {
            this.attRight = attRight;
        }

    }

    @Entity
    @Table(name = "rights")
    public class Right implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        public Long getId() {
            return id;
        }

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

    }

UML

Unidirectional ManyToMany UML relationship

Kukulkan Grammar

    entity Left {
        ManyToMany attsRight: Right
    }
    entity Right {}

Data Model

Unidirectional ManyToMany Data Model

Foreign Keys:

From lefts_atts_right table to lefts table: fk_lefts_atts_right.left_id_lefts.id
From lefts_atts_right table to rights table: fk_lefts_atts_right.att_right_id.rights.id

Java (POJO)

    @Entity
    @Table(name = "lefts")
    public class Left implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @ManyToMany
        @JoinTable(name = "lefts_atts_right", 
        joinColumns = JoinColumn(name="left_id", referencedColumnName="id"),
        inverseJoinColumns = 
        @JoinColumn(name="att_right_id", referencedColumnName="id"))
        private Set<Right> attsRight = new HashSet<>();

        public Long getId() {
            return id;
        }

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

        public Set<Right> getAttsRight() {
            return attsRight;
        }

        public void setAttsRight(Set<Right> attsRight) {
            this.attsRight = attsRight;
        }

        public Left addAttRight (Right attsRight) {
            this.attsRight.add(attsRight);
            attsRight.getLeft().add(this);
            return this;
        }

        public Left removeAttRight(Right attsRight) {
            this.attsRight.remove(attsRight);
            attsRight.getLeft().remove(this);
            return this;
        } 

    }

    @Entity
    @Table(name = "rights")
    public class Right implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        public Long getId() {
            return id;
        }

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

    }

UML

Bidirectional OneToOne UML relationship

Kukulkan Grammar

    entity Left {
        OneToOne (attLeft) attRight: Right
    }
    entity Right {}

Data Model

Bidirectional OneToOne Data Model

Foreign Keys:

From lefts table to rights table: fk_lefts.att_right_id_rights.id

Java (POJO)

    @Entity
    @Table(name = "lefts")
    public class Left implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @OneToOne
        @JoinColumn(name = "att_right_id", unique = true)
        private Right attRight;

        public Long getId() {
            return id;
        }

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

        public Right getAttRight() {
            return attRight;
        }

        public void setAttRight(Right attRight) {
            this.attRight = attRight;
        }

    }

    @Entity
    @Table(name = "rights")
    public class Right implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @OneToOne(mappedBy = "attRight")
        private Left attLeft;

        public Long getId() {
            return id;
        }

        public void setId(Long id) {
        this.id = id;
        }    
        
        public Left getAttLeft() {
            return attLeft;
        }

        public void setAttLeft(Left attLeft) {
            this.attLeft = attLeft;
        }

    }

UML

Bidirectional OneToMany UML relationship

Kukulkan Grammar

    entity Left {
        OneToMany (attLeft) attsRight: Right
    }
    entity Right {}

Data Model

Bidirectional OneToMany Data Model

Foreign Keys:

From rights table to lefts table: fk_rights.att_left_id_lefts.id

Java (POJO)

    @Entity
    @Table(name = "lefts")
    public class Left implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @OneToMany(mappedBy = "attLeft")
        @JsonIgnore
        private Set<Right> attsRight = new HashSet<>();

        public Long getId() {
            return id;
        }

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

        public Set<Right> getAttsRight() {
            return attsRight;
        }

        public void setAttsRight(Set<Right> attsRight) {
            this.attsRight = attsRight;
        }

        public Left addAttRight (Right attRight) {
            this.attsRight.add(attRight);
            attRight.getLeft().add(this);
            return this;
        }

        public Left removeAttRight(Right attRight) {
            this.attsRight.remove(attRight);
            attRight.getLeft().remove(this);
            return this;
        } 

    }

    @Entity
    @Table(name = "rights")
    public class Right implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @ManyToOne
        @JoinColumn(name = "att_left_id")
        private Left attLeft;

        public Long getId() {
            return id;
        }

        public void setId(Long id) {
        this.id = id;
        }    
        
        public Left getAttLeft() {
            return attLeft;
        }

        public void setAttLeft(Left attLeft) {
            this.attLeft = attLeft;
        }

    }

UML

Bidirectional ManyToOne UML relationship

Kukulkan Grammar

    entity Left {
        ManyToOne (attsLeft) attRight: Right
    }
    entity Right {}

Data Model

Bidirectional ManyToOne Data Model

Foreign Keys:

From lefts table to rights table: fk_lefts.att_right_id_rights.id

Java (POJO)

    @Entity
    @Table(name = "lefts")
    public class Left implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @ManyToOne
        @JoinColumn(name = "att_right_id")
        private Right attRight;

        public Long getId() {
            return id;
        }

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

        public Right getAttRight() {
            return attRight;
        }

        public void setAttRight(Right attRight) {
            this.attRight = attRight;
        }

    }

    @Entity
    @Table(name = "rights")
    public class Right implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @OneToMany(mappedBy = "attRight")
        private Set<Left> attsLeft = new HashSet<>();

        public Long getId() {
            return id;
        }

        public void setId(Long id) {
        this.id = id;
        }	    
        
        public Set<Left> getAttsLeft() {
            return attsLeft;
        }

        public void setAttsLeft(Set<Left> attsLeft) {
            this.attsLeft = attsLeft;
        }

    }

UML

Bidirectional ManyToMany UML relationship

Kukulkan Grammar

    entity Left {
        ManyToMany (attsLeft) attsRight: Right
    }
    entity Right {}

Data Model

Bidirectional ManyToMany Data Model

Foreign Keys:

From atts_left_atts_right table to lefts table: fk_atts_left_atts_right.att_left_id_lefts.id
From atts_left_atts_right table to rights table: fk_atts_left_atts_right.att_right_id.rights.id

Java (POJO)

    @Entity
    @Table(name = "lefts")
    public class Left implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @ManyToMany
        @JoinTable(name = "atts_left_atts_right", 
        joinColumns = JoinColumn(name="att_left_id", referencedColumnName="id"),
        inverseJoinColumns = 
        @JoinColumn(name="att_right_id", referencedColumnName="id"))
        private Set<Right> attsRight = new HashSet<>();

        public Long getId() {
            return id;
        }

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

        public Set<Right> getAttsRight() {
            return attsRight;
        }

        public void setAttsRight(Set<Right> attsRight) {
            this.attsRight = attsRight;
        }

        public Left addAttRight (Right attsRight) {
            this.attsRight.add(attsRight);
            attsRight.getLeft().add(this);
            return this;
        }

        public Left removeAttRight(Right attsRight) {
            this.attsRight.remove(attsRight);
            attsRight.getLeft().remove(this);
            return this;
        } 

    }

    @Entity
    @Table(name = "rights")
    public class Right implements Serializable {
        private static final long serialVersionUID = 1L;

        @Id
        @GeneratedValue(strategy = GenerationType.IDENTITY)
        @Column(name = "id", unique = true, nullable = false)
        private Long id;

        @ManyToMany(mappedBy = "attsRight")
        @JsonIgnore
        private Set<Left> attsLeft = new HashSet<>();

        public Long getId() {
            return id;
        }

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

        public Set<Left> getLefts() {
            return attsLeft;
        }

        public void setLefts(Set<Left> attsLeft) {
            this.attsLeft = attsLeft;
        }

        public Right addLeft(Left left) {
            this.attsLeft.add(left);
            left.getAttsRight().add(this);
            return this;
        }

        public Right removeLeft(Lefts left) {
            this.lefts.remove(left);
            lefts.getAttsRight().remove(this);
            return this;
        }  

    }