Øredev 2016; Malmö, Sweden; 9 November 2016; video is here: https://www.youtube.com/watch?v=03PXmPc7Q3g

1. /20@yegor256 1
ORM is an Offensive
Anti-Pattern
Yegor Bugayenko

2. /20@yegor256 2
what’s wrong
with data?

3. /20@yegor256 3
ANSI C
typedef struct {
int x;
int y;
} Point;
void moveTo(Point p, int dx, int dy) {
p.x += dx;
if (p.x > 640) { p.x = 640; }
p.y += dy;
if (p.y > 480) { p.y = 480; }
}
void draw(Point p, Canvas c) {
c.put(p.x, p.y, “black”);
}

4. /20@yegor256 4
typedef struct {
int x;
int y;
int color; // here!
int scale; // here!
} Point;
void moveTo(Point p, int dx, int dy) {
p.x += dx;
if (p.x > 640) { p.x = 640; }
p.y += dy;
if (p.y > 480) { p.y = 480; }
}
void draw(Point p, Canvas c) {
c.put(p.x, p.y, “black”);
}

5. /20@yegor256 5
maintainability
command & control trust & delegatevs

6. /20@yegor256 6
class Point {
private int x;
private int y;
void moveTo(int dx, int dy) {
this.x += dx;
if (this.x > 640) { this.x = 640; }
this.y += dy;
if (this.y > 480) { this.y = 480; }
}
void draw(Canvas c) {
c.put(this.x, this.y, “black”);
}
}

7. /20@yegor256 7
encapsulation

8. /20@yegor256 8
Java
class Point {
private int x;
private int y;
public int getX() { return this.x; }
public int getX() { return this.y; }
public void setX(int x) { this.x = x; }
public void setY(int y) { this.y = y; }
}
class PointUtils {
static void moveTo(Point p, int dx, int dy) {
p.setX(p.getX() + dx);
if (p.getX() > 640) { p.setX(640); }
p.setY(p.getY() + dy);
if (p.getY() > 480) { p.setY(480); }
}
static void draw(Point p, Canvas c) {
c.put(p.getX(), p.getY(), “black”);
}
}

9. /20@yegor256 9
ORM/JPA/Hibernate

10. /20@yegor256 10
@Entity
@Table(name = "point")
public class Point {
private int id;
@Id
@GeneratedValue
public int getId() { return this.id; }
@Column(name = "x")
public int getX() { return this.x; }
public void setX(int x) { this.x = x; }
@Column(name = "y")
public int getY() { return this.y; }
public void setY(int y) { this.y = y; }
}

11. /20@yegor256 11
void static moveTo(int id, int dx, int dy) {
Session session = factory.openSession();
try {
Transaction txn = session.beginTransaction();
Query query = session.createQuery(“SELECT p FROM point WHERE id=:id”);
query.setParameter(“:id”, id);
Point p = query.list().get(0);
p.setX(p.getX() + dx);
p.setY(p.getY() + dy);
session.update(p);
txn.commit();
} catch (HibernateException ex) {
txn.rollback();
} finally {
session.close();
}
}

12. /20@yegor256 12
PostgreSQL
JDBC
UPDATE point
SET x = “100”, y = “120”
WHERE id = 123
p.getX();
p.getY();
statement.executeUpdate();setX()
Query query = session.createQuery(“SELECT p FROM point WHERE id=:id”);
query.setParameter(“:id”, id);
Point p = query.list().get(0);
p.setX(p.getX() + dx);
p.setY(p.getY() + dy);
session.update(p);
update()Point
Session
setY()

13. /20@yegor256 13
JDBC
Point
Session
client

14. /20@yegor256 14
what is the
alternative?

15. /20@yegor256 15
JDBC
Point
adapter
client

16. /20@yegor256 16
PostgreSQL
JDBC
UPDATE point
SET x = “100”, y = “120”
WHERE id = 123
statement.executeUpdate();
Point p = new Point(123, db);
p.moveTo(50, 70);
moveTo()
Point
x.update(“point”)
.set(“x”, this.x)
.set(“y”, this.y)
.where(“id”, this.id)
.execute();
jOOQ

17. /20@yegor256 17
class Point {
private final DB db;
private final int id;
public void moveTo(int dx, int dy) {
this.db.update(“point”)
.set(“x”, ??)
.set(“y”, ??)
.where(“id”, this.id)
.execute();
}
}

18. /20@yegor256 18
no mapping!

19. /20@yegor256 19
jOOQ
jcabi-jdbc
JDBC JDBI
DbUtils
Yank

20. /20@yegor256 20
Volume 2
Section 6.5

21. /20@yegor256 21
Point p = new Point(new Cached(mysql));
p.draw(canvas1);
p.draw(canvas2);
cache

22. /20@yegor256 22
class Point extends ActiveRecord {
protected int x;
protected int y;
void moveTo(int dx, int dy) {
this.x += dx;
this.y += dy;
this.update(); // from parent class
}
}
ActiveRecord

23. /20@yegor256 23
class Point {
void moveUp(int dy) {
// UPDATE point SET y = ?
}
void moveRight(int dx) {
// UPDATE point SET x = ?
}
void moveTo(int dx, int dy) {
// UPDATE point SET x = ?, y = ?
}
}
updates

24. /20@yegor256 24
db = new TransactionAwareDB(db);
db.start();
try {
Point p1 = new Point(1, db);
Point p2 = new Point(2, db);
p1.moveTo(15, 30);
p2.moveTo(7, 13);
db.commit();
} catch (Exception ex) {
db.rollback();
}
transactions