Bael 1337 (#3072)

* inheritance ex

* add more ex and tests, formatting

hibernate5/src/main/java/com/baeldung/hibernate/HibernateUtil.java

@@ -12,6 +12,16 @@ import com.baeldung.hibernate.pojo.Course;
 import com.baeldung.hibernate.pojo.Student;
 import com.baeldung.hibernate.pojo.User;
 import com.baeldung.hibernate.pojo.UserProfile;
+import com.baeldung.hibernate.pojo.inheritance.Animal;
+import com.baeldung.hibernate.pojo.inheritance.Bag;
+import com.baeldung.hibernate.pojo.inheritance.Book;
+import com.baeldung.hibernate.pojo.inheritance.Car;
+import com.baeldung.hibernate.pojo.inheritance.MyEmployee;
+import com.baeldung.hibernate.pojo.inheritance.MyProduct;
+import com.baeldung.hibernate.pojo.inheritance.Pen;
+import com.baeldung.hibernate.pojo.inheritance.Person;
+import com.baeldung.hibernate.pojo.inheritance.Pet;
+import com.baeldung.hibernate.pojo.inheritance.Vehicle;
 
 import org.hibernate.SessionFactory;
 import org.hibernate.boot.Metadata;
@@ -50,6 +60,16 @@ public class HibernateUtil {
         metadataSources.addAnnotatedClass(OrderEntry.class);
         metadataSources.addAnnotatedClass(OrderEntryIdClass.class);
         metadataSources.addAnnotatedClass(UserProfile.class);
+        metadataSources.addAnnotatedClass(Book.class);
+        metadataSources.addAnnotatedClass(MyEmployee.class);
+        metadataSources.addAnnotatedClass(MyProduct.class);
+        metadataSources.addAnnotatedClass(Pen.class);
+        metadataSources.addAnnotatedClass(Person.class);
+        metadataSources.addAnnotatedClass(Animal.class);
+        metadataSources.addAnnotatedClass(Pet.class);
+        metadataSources.addAnnotatedClass(Vehicle.class);
+        metadataSources.addAnnotatedClass(Car.class);
+        metadataSources.addAnnotatedClass(Bag.class);
 
         Metadata metadata = metadataSources.buildMetadata();
         return metadata.getSessionFactoryBuilder()

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/Animal.java

@@ -0,0 +1,40 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Inheritance;
+import javax.persistence.InheritanceType;
+
+@Entity
+@Inheritance(strategy = InheritanceType.JOINED)
+public class Animal {
+
+    @Id
+    private long animalId;
+
+    private String species;
+    
+    public Animal() {}    
+
+    public Animal(long animalId, String species) {
+        this.animalId = animalId;
+        this.species = species;
+    }
+
+    public long getAnimalId() {
+        return animalId;
+    }
+
+    public void setAnimalId(long animalId) {
+        this.animalId = animalId;
+    }
+
+    public String getSpecies() {
+        return species;
+    }
+
+    public void setSpecies(String species) {
+        this.species = species;
+    }
+
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/Bag.java

@@ -0,0 +1,38 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+
+import org.hibernate.annotations.Polymorphism;
+import org.hibernate.annotations.PolymorphismType;
+
+@Entity
+@Polymorphism(type = PolymorphismType.EXPLICIT)
+public class Bag implements Item {
+
+    @Id
+    private long bagId;
+
+    private String type;
+
+    public Bag(long bagId, String type) {
+        this.bagId = bagId;
+        this.type = type;
+    }
+
+    public long getBagId() {
+        return bagId;
+    }
+
+    public void setBagId(long bagId) {
+        this.bagId = bagId;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/Book.java

@@ -0,0 +1,27 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+import javax.persistence.DiscriminatorValue;
+import javax.persistence.Entity;
+
+@Entity
+@DiscriminatorValue("1")
+public class Book extends MyProduct {
+    private String author;
+
+    public Book() {
+    }
+
+    public Book(long productId, String name, String author) {
+        super(productId, name);
+        this.author = author;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    public void setAuthor(String author) {
+        this.author = author;
+    }
+
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/Car.java

@@ -0,0 +1,25 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+import javax.persistence.Entity;
+
+@Entity
+public class Car extends Vehicle {
+    private String engine;
+
+    public Car() {
+    }
+
+    public Car(long vehicleId, String manufacturer, String engine) {
+        super(vehicleId, manufacturer);
+        this.engine = engine;
+    }
+
+    public String getEngine() {
+        return engine;
+    }
+
+    public void setEngine(String engine) {
+        this.engine = engine;
+    }
+
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/Item.java

@@ -0,0 +1,5 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+public interface Item {
+
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/MyEmployee.java

@@ -0,0 +1,22 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+import javax.persistence.Entity;
+
+@Entity
+public class MyEmployee extends Person {
+    private String company;
+
+    public MyEmployee(long personId, String name, String company) {
+        super(personId, name);
+        this.company = company;
+    }
+
+    public String getCompany() {
+        return company;
+    }
+
+    public void setCompany(String company) {
+        this.company = company;
+    }
+
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/MyProduct.java

@@ -0,0 +1,47 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+import javax.persistence.DiscriminatorColumn;
+import javax.persistence.DiscriminatorType;
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Inheritance;
+import javax.persistence.InheritanceType;
+
+import org.hibernate.annotations.DiscriminatorFormula;
+
+@Entity
+@Inheritance(strategy = InheritanceType.SINGLE_TABLE)
+@DiscriminatorColumn(name = "product_type", discriminatorType = DiscriminatorType.INTEGER)
+// @DiscriminatorFormula("case when author is not null then 1 else 2 end")
+public class MyProduct {
+    @Id
+    private long productId;
+
+    private String name;
+
+    public MyProduct() {
+    }
+
+    public MyProduct(long productId, String name) {
+        super();
+        this.productId = productId;
+        this.name = name;
+    }
+
+    public long getProductId() {
+        return productId;
+    }
+
+    public void setProductId(long productId) {
+        this.productId = productId;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/Pen.java

@@ -0,0 +1,27 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+import javax.persistence.DiscriminatorValue;
+import javax.persistence.Entity;
+
+@Entity
+@DiscriminatorValue("2")
+public class Pen extends MyProduct {
+    private String color;
+
+    public Pen() {
+    }
+
+    public Pen(long productId, String name, String color) {
+        super(productId, name);
+        this.color = color;
+    }
+
+    public String getColor() {
+        return color;
+    }
+
+    public void setColor(String color) {
+        this.color = color;
+    }
+
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/Person.java

@@ -0,0 +1,38 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+import javax.persistence.Id;
+import javax.persistence.MappedSuperclass;
+
+@MappedSuperclass
+public class Person {
+
+    @Id
+    private long personId;
+
+    private String name;
+
+    public Person() {
+    }
+
+    public Person(long personId, String name) {
+        this.personId = personId;
+        this.name = name;
+    }
+
+    public long getPersonId() {
+        return personId;
+    }
+
+    public void setPersonId(long personId) {
+        this.personId = personId;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/Pet.java

@@ -0,0 +1,27 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+import javax.persistence.Entity;
+import javax.persistence.PrimaryKeyJoinColumn;
+
+@Entity
+@PrimaryKeyJoinColumn(name = "petId")
+public class Pet extends Animal {
+    private String name;
+
+    public Pet() {
+    }
+
+    public Pet(long animalId, String species, String name) {
+        super(animalId, species);
+        this.name = name;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+}

hibernate5/src/main/java/com/baeldung/hibernate/pojo/inheritance/Vehicle.java

@@ -0,0 +1,40 @@
+package com.baeldung.hibernate.pojo.inheritance;
+
+import javax.persistence.Entity;
+import javax.persistence.Id;
+import javax.persistence.Inheritance;
+import javax.persistence.InheritanceType;
+
+@Entity
+@Inheritance(strategy = InheritanceType.TABLE_PER_CLASS)
+public class Vehicle {
+    @Id
+    private long vehicleId;
+
+    private String manufacturer;
+
+    public Vehicle() {
+    }
+
+    public Vehicle(long vehicleId, String manufacturer) {
+        this.vehicleId = vehicleId;
+        this.manufacturer = manufacturer;
+    }
+
+    public long getVehicleId() {
+        return vehicleId;
+    }
+
+    public void setVehicleId(long vehicleId) {
+        this.vehicleId = vehicleId;
+    }
+
+    public String getManufacturer() {
+        return manufacturer;
+    }
+
+    public void setManufacturer(String manufacturer) {
+        this.manufacturer = manufacturer;
+    }
+
+}

hibernate5/src/test/java/com/baeldung/hibernate/InheritanceMappingIntegrationTest.java

@@ -0,0 +1,89 @@
+package com.baeldung.hibernate;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.io.IOException;
+
+import org.hibernate.Session;
+import org.hibernate.Transaction;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.baeldung.hibernate.pojo.inheritance.Bag;
+import com.baeldung.hibernate.pojo.inheritance.Book;
+import com.baeldung.hibernate.pojo.inheritance.Car;
+import com.baeldung.hibernate.pojo.inheritance.MyEmployee;
+import com.baeldung.hibernate.pojo.inheritance.Pen;
+import com.baeldung.hibernate.pojo.inheritance.Pet;
+
+public class InheritanceMappingIntegrationTest {
+    private Session session;
+
+    private Transaction transaction;
+
+    @Before
+    public void setUp() throws IOException {
+        session = HibernateUtil.getSessionFactory()
+            .openSession();
+        transaction = session.beginTransaction();
+    }
+
+    @After
+    public void tearDown() {
+        transaction.rollback();
+        session.close();
+    }
+
+    @Test
+    public void givenSubclasses_whenQuerySingleTableSuperclass_thenOk() {
+        Book book = new Book(1, "1984", "George Orwell");
+        session.save(book);
+        Pen pen = new Pen(2, "my pen", "blue");
+        session.save(pen);
+
+        assertThat(session.createQuery("from MyProduct")
+            .getResultList()
+            .size()).isEqualTo(2);
+    }
+
+    @Test
+    public void givenSubclasses_whenQueryMappedSuperclass_thenOk() {
+        MyEmployee emp = new MyEmployee(1, "john", "baeldung");
+        session.save(emp);
+
+        assertThat(session.createQuery("from com.baeldung.hibernate.pojo.inheritance.Person")
+            .getResultList()
+            .size()).isEqualTo(1);
+    }
+
+    @Test
+    public void givenSubclasses_whenQueryJoinedTableSuperclass_thenOk() {
+        Pet pet = new Pet(1, "dog", "lassie");
+        session.save(pet);
+
+        assertThat(session.createQuery("from Animal")
+            .getResultList()
+            .size()).isEqualTo(1);
+    }
+
+    @Test
+    public void givenSubclasses_whenQueryTablePerClassSuperclass_thenOk() {
+        Car car = new Car(1, "audi", "xyz");
+        session.save(car);
+
+        assertThat(session.createQuery("from Vehicle")
+            .getResultList()
+            .size()).isEqualTo(1);
+    }
+
+    @Test
+    public void givenSubclasses_whenQueryNonMappedInterface_thenOk() {
+        Bag bag = new Bag(1, "large");
+        session.save(bag);
+
+        assertThat(session.createQuery("from com.baeldung.hibernate.pojo.inheritance.Item")
+            .getResultList()
+            .size()).isEqualTo(0);
+    }
+}