BAEL-2814 Added files for article (eugenp#6968)

nyko03 · May 22, 2019 · 93f54b1 · 93f54b1
1 parent cb810de
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diff --git a/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/projections/Product.java b/persistence-modules/java-jpa/src/main/java/com/baeldung/jpa/projections/Product.java
@@ -0,0 +1,50 @@
+package com.baeldung.jpa.projections;
+
+import java.math.BigDecimal;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.GenerationType;
+import javax.persistence.Id;
+
+@Entity
+public class Product {
+    @Id
+    private long id;
+    private String name;
+    private String description;
+    private String category;
+    private BigDecimal unitPrice;
+
+    public long getId() {
+        return id;
+    }
+    public void setId(long id) {
+        this.id = id;
+    }
+    public String getName() {
+        return name;
+    }
+    public void setName(String name) {
+        this.name = name;
+    }
+    public String getDescription() {
+        return description;
+    }
+    public void setDescription(String description) {
+        this.description = description;
+    }
+    public String getCategory() {
+        return category;
+    }
+    public void setCategory(String category) {
+        this.category = category;
+    }
+    public BigDecimal getUnitPrice() {
+        return unitPrice;
+    }
+    public void setUnitPrice(BigDecimal unitPrice) {
+        this.unitPrice = unitPrice;
+    }
+
+}
diff --git a/...stence-modules/java-jpa/src/main/java/com/baeldung/jpa/projections/ProductRepository.java b/...stence-modules/java-jpa/src/main/java/com/baeldung/jpa/projections/ProductRepository.java
@@ -0,0 +1,93 @@
+package com.baeldung.jpa.projections;
+
+import java.util.List;
+
+import javax.persistence.EntityManager;
+import javax.persistence.EntityManagerFactory;
+import javax.persistence.Persistence;
+import javax.persistence.Query;
+import javax.persistence.Tuple;
+import javax.persistence.criteria.CriteriaBuilder;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Root;
+
+public class ProductRepository {
+    private EntityManager entityManager;
+
+    public ProductRepository() {
+        EntityManagerFactory factory = Persistence.createEntityManagerFactory("jpa-projections");
+        entityManager = factory.createEntityManager();
+    }
+
+    @SuppressWarnings("unchecked")
+    public List<Object> findAllNamesUsingJPQL() {
+        Query query = entityManager.createQuery("select name from Product");
+        List<Object> resultList = query.getResultList();
+        return resultList;
+    }
+
+    @SuppressWarnings("unchecked")
+    public List<Object> findAllIdsUsingJPQL() {
+        Query query = entityManager.createQuery("select id from Product");
+        List<Object> resultList = query.getResultList();
+        return resultList;
+    }
+
+    public List<String> findAllNamesUsingCriteriaBuilder() {
+        CriteriaBuilder builder = entityManager.getCriteriaBuilder();
+        CriteriaQuery<String> query = builder.createQuery(String.class);
+        Root<Product> product = query.from(Product.class);
+        query.select(product.get("name"));
+        List<String> resultList = entityManager.createQuery(query).getResultList();
+        return resultList;
+    }
+
+    @SuppressWarnings("unchecked")
+    public List<Object[]> findAllIdAndNamesUsingJPQL() {
+        Query query = entityManager.createQuery("select id, name from Product");
+        List<Object[]> resultList = query.getResultList();
+        return resultList;
+    }
+
+    public List<Object[]> findAllIdAndNamesUsingCriteriaBuilderArray() {
+        CriteriaBuilder builder = entityManager.getCriteriaBuilder();
+        CriteriaQuery<Object[]> query = builder.createQuery(Object[].class);
+        Root<Product> product = query.from(Product.class);
+        query.select(builder.array(product.get("id"), product.get("name")));
+        List<Object[]> resultList = entityManager.createQuery(query).getResultList();
+        return resultList;
+    }
+
+    public List<Object[]> findAllIdNameUnitPriceUsingCriteriaQueryMultiselect() {
+        CriteriaBuilder builder = entityManager.getCriteriaBuilder();
+        CriteriaQuery<Object[]> query = builder.createQuery(Object[].class);
+        Root<Product> product = query.from(Product.class);
+        query.multiselect(product.get("id"), product.get("name"), product.get("unitPrice"));
+        List<Object[]> resultList = entityManager.createQuery(query).getResultList();
+        return resultList;
+    }
+
+    public List<Tuple> findAllIdAndNamesUsingCriteriaBuilderTuple() {
+        CriteriaBuilder builder = entityManager.getCriteriaBuilder();
+        CriteriaQuery<Tuple> query = builder.createQuery(Tuple.class);
+        Root<Product> product = query.from(Product.class);
+        query.select(builder.tuple(product.get("id"), product.get("name")));
+        List<Tuple> resultList = entityManager.createQuery(query).getResultList();
+        return resultList;
+    }
+
+    public List<Object[]> findCountByCategoryUsingJPQL() {
+        Query query = entityManager.createQuery("select p.category, count(p) from Product p group by p.category");
+        return query.getResultList();
+    }
+
+    public List<Object[]> findCountByCategoryUsingCriteriaBuilder() {
+        CriteriaBuilder builder = entityManager.getCriteriaBuilder();
+        CriteriaQuery<Object[]> query = builder.createQuery(Object[].class);
+        Root<Product> product = query.from(Product.class);
+        query.multiselect(product.get("category"), builder.count(product));
+        query.groupBy(product.get("category"));
+        List<Object[]> resultList = entityManager.createQuery(query).getResultList();
+        return resultList;
+    }
+}
diff --git a/persistence-modules/java-jpa/src/main/resources/META-INF/persistence.xml b/persistence-modules/java-jpa/src/main/resources/META-INF/persistence.xml
@@ -147,7 +147,7 @@
             <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false" />
         </properties>
     </persistence-unit>
-    
+
     <persistence-unit name="jpa-entity-definition">
         <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
         <class>com.baeldung.jpa.entity.Student</class>
@@ -163,4 +163,21 @@
             <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false" />
         </properties>
     </persistence-unit>
+
+    <persistence-unit name="jpa-projections">
+        <provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
+        <class>com.baeldung.jpa.projections.Product</class>
+        <exclude-unlisted-classes>true</exclude-unlisted-classes>
+        <properties>
+            <property name="javax.persistence.jdbc.driver" value="org.h2.Driver"/>
+            <property name="javax.persistence.jdbc.url" value="jdbc:h2:mem:test"/>
+            <property name="javax.persistence.jdbc.user" value="sa"/>
+            <property name="javax.persistence.jdbc.password" value=""/>
+            <property name="hibernate.dialect" value="org.hibernate.dialect.H2Dialect"/>
+            <property name="hibernate.hbm2ddl.auto" value="create-drop"/>
+            <property name="show_sql" value="true"/>
+            <property name="hibernate.temp.use_jdbc_metadata_defaults" value="false"/>
+            <property name="javax.persistence.sql-load-script-source" value="products_jpa.sql"/>
+        </properties>
+    </persistence-unit>
 </persistence>
diff --git a/persistence-modules/java-jpa/src/main/resources/products_jpa.sql b/persistence-modules/java-jpa/src/main/resources/products_jpa.sql
@@ -0,0 +1,4 @@
+insert into product(id, name, description, category) values (1,'Product Name 1','This is Product 1', 'category1');
+insert into product(id, name, description, category) values (2,'Product Name 2','This is Product 2', 'category1');
+insert into product(id, name, description, category) values (3,'Product Name 3','This is Product 3', 'category2');
+insert into product(id, name, description, category) values (4,'Product Name 4','This is Product 4', 'category3');
diff --git a/...a-jpa/src/test/java/com/baeldung/jpa/projections/HibernateProjectionsIntegrationTest.java b/...a-jpa/src/test/java/com/baeldung/jpa/projections/HibernateProjectionsIntegrationTest.java
@@ -0,0 +1,133 @@
+package com.baeldung.jpa.projections;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertNotNull;
+
+import java.util.List;
+
+import org.hibernate.Criteria;
+import org.hibernate.Session;
+import org.hibernate.SessionFactory;
+import org.hibernate.Transaction;
+import org.hibernate.cfg.AvailableSettings;
+import org.hibernate.cfg.Configuration;
+import org.hibernate.criterion.Order;
+import org.hibernate.criterion.Projections;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.BeforeClass;
+import org.junit.Test;
+
+public class HibernateProjectionsIntegrationTest {
+    private static Session session;
+    private static SessionFactory sessionFactory;
+    private Transaction transaction;
+
+    @BeforeClass
+    public static void init() {
+        Configuration configuration = getConfiguration();
+        configuration.addAnnotatedClass(Product.class);
+        sessionFactory = configuration.buildSessionFactory();
+    }    
+
+    @Before
+    public void before() {
+        session = sessionFactory.getCurrentSession();
+        transaction = session.beginTransaction();        
+    }   
+
+    @After
+    public void after() {
+        if(transaction.isActive()) {
+            transaction.rollback();
+        }
+    }  
+
+    private static Configuration getConfiguration() {
+        Configuration cfg = new Configuration();
+        cfg.setProperty(AvailableSettings.DIALECT,
+            "org.hibernate.dialect.H2Dialect");
+        cfg.setProperty(AvailableSettings.HBM2DDL_AUTO, "none");
+        cfg.setProperty(AvailableSettings.DRIVER, "org.h2.Driver");
+        cfg.setProperty(AvailableSettings.URL,
+            "jdbc:h2:mem:myexceptiondb2;DB_CLOSE_DELAY=-1;;INIT=RUNSCRIPT FROM 'src/test/resources/products.sql'");
+        cfg.setProperty(AvailableSettings.USER, "sa");
+        cfg.setProperty(AvailableSettings.PASS, "");
+        cfg.setProperty(AvailableSettings.CURRENT_SESSION_CONTEXT_CLASS, "thread");
+        return cfg;
+    }
+
+
+    @SuppressWarnings("deprecation")
+    @Test
+    public void givenProductData_whenIdAndNameProjectionUsingCriteria_thenListOfObjectArrayReturned() {
+        Criteria criteria = session.createCriteria(Product.class);
+        criteria = criteria.setProjection(Projections.projectionList()
+            .add(Projections.id())
+            .add(Projections.property("name")));
+        List<Object[]> resultList = criteria.list();
+
+        assertNotNull(resultList);
+        assertEquals(4, resultList.size());
+        assertEquals(1L, resultList.get(0)[0]);
+        assertEquals("Product Name 1", resultList.get(0)[1]);
+        assertEquals(2L, resultList.get(1)[0]);
+        assertEquals("Product Name 2", resultList.get(1)[1]);
+        assertEquals(3L, resultList.get(2)[0]);
+        assertEquals("Product Name 3", resultList.get(2)[1]);
+        assertEquals(4L, resultList.get(3)[0]);
+        assertEquals("Product Name 4", resultList.get(3)[1]);
+    }
+
+
+    @Test
+    public void givenProductData_whenNameProjectionUsingCriteria_thenListOfStringReturned() {
+        Criteria criteria = session.createCriteria(Product.class);
+        criteria = criteria.setProjection(Projections.property("name"));
+        List resultList = criteria.list();
+
+        assertNotNull(resultList);
+        assertEquals(4, resultList.size());
+        assertEquals("Product Name 1", resultList.get(0));
+        assertEquals("Product Name 2", resultList.get(1));
+        assertEquals("Product Name 3", resultList.get(2));
+        assertEquals("Product Name 4", resultList.get(3));
+    }
+
+    @Test
+    public void givenProductData_whenCountByCategoryUsingCriteria_thenOK() {
+        Criteria criteria = session.createCriteria(Product.class);
+        criteria = criteria.setProjection(Projections.projectionList()
+            .add(Projections.groupProperty("category"))
+            .add(Projections.rowCount()));
+        List<Object[]> resultList = criteria.list();
+
+        assertNotNull(resultList);
+        assertEquals(3, resultList.size());
+        assertEquals("category1", resultList.get(0)[0]);
+        assertEquals(2L, resultList.get(0)[1]);
+        assertEquals("category2", resultList.get(1)[0]);
+        assertEquals(1L, resultList.get(1)[1]);
+        assertEquals("category3", resultList.get(2)[0]);
+        assertEquals(1L, resultList.get(2)[1]);
+    }
+
+    @Test
+    public void givenProductData_whenCountByCategoryWithAliasUsingCriteria_thenOK() {
+        Criteria criteria = session.createCriteria(Product.class);
+        criteria = criteria.setProjection(Projections.projectionList()
+            .add(Projections.groupProperty("category"))
+            .add(Projections.alias(Projections.rowCount(), "count")));
+        criteria.addOrder(Order.asc("count"));
+        List<Object[]> resultList = criteria.list();
+
+        assertNotNull(resultList);
+        assertEquals(3, resultList.size());
+        assertEquals("category2", resultList.get(0)[0]);
+        assertEquals(1L, resultList.get(0)[1]);
+        assertEquals("category3", resultList.get(1)[0]);
+        assertEquals(1L, resultList.get(1)[1]);
+        assertEquals("category1", resultList.get(2)[0]);
+        assertEquals(2L, resultList.get(2)[1]);
+    }
+}