BAEL-2227 JPA Criteria Queries In Clause (#5606)

* BAEL-2159: Mini Article on "Separate double into integer and decimal parts"

* BEAL-2227: JPA Criteria Query In clause - Tutorial.

* Minor Fix: Changed type of Predicate.

* BAEL-2227: Code Review Comments: Extracted criteriaBuilder to a field. Refactored a private method to create criteria query.

* BAEL-2227: Fixed spelling mistakes in the code.

persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/entities/DeptEmployee.java

@@ -23,6 +23,14 @@ public class DeptEmployee {
         this.department = department;
     }
     
+    public DeptEmployee(String name, String employeeNumber, String designation, Department department) {
+        super();
+        this.name = name;
+        this.employeeNumber = employeeNumber;
+        this.designation = designation;
+        this.department = department;
+    }
+
     public long getId() {
         return id;
     }

persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/jpacriteriabuilder/service/EmployeeSearchService.java

@@ -0,0 +1,15 @@
+package com.baeldung.hibernate.jpacriteriabuilder.service;
+
+import java.util.List;
+
+import com.baeldung.hibernate.entities.DeptEmployee;
+
+public interface EmployeeSearchService {
+
+    List<DeptEmployee> filterbyDesignationUsingCriteriaBuilder(List<String> designaitons);
+
+    List<DeptEmployee> filterbyDesignationUsingExpression(List<String> aurhors);
+
+    List<DeptEmployee> searchByDepartmentQuery(String query);
+
+}

persistence-modules/hibernate5/src/main/java/com/baeldung/hibernate/jpacriteriabuilder/service/EmployeeSearchServiceImpl.java

@@ -0,0 +1,77 @@
+package com.baeldung.hibernate.jpacriteriabuilder.service;
+
+import java.util.List;
+
+import javax.persistence.EntityManager;
+import javax.persistence.TypedQuery;
+import javax.persistence.criteria.CriteriaBuilder;
+import javax.persistence.criteria.CriteriaBuilder.In;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Root;
+import javax.persistence.criteria.Subquery;
+
+import com.baeldung.hibernate.entities.Department;
+import com.baeldung.hibernate.entities.DeptEmployee;
+
+public class EmployeeSearchServiceImpl implements EmployeeSearchService {
+
+    private EntityManager entityManager;
+    private CriteriaBuilder criteriaBuilder;
+
+    public EmployeeSearchServiceImpl(EntityManager entityManager) {
+        this.entityManager = entityManager;
+        this.criteriaBuilder = entityManager.getCriteriaBuilder();
+        
+    }
+
+    @Override
+    public List<DeptEmployee> filterbyDesignationUsingCriteriaBuilder(List<String> designations) {
+        CriteriaQuery<DeptEmployee> criteriaQuery = createCriteriaQuery(DeptEmployee.class);
+        Root<DeptEmployee> root = criteriaQuery.from(DeptEmployee.class);
+        In<String> inClause = criteriaBuilder.in(root.get("designation"));
+        for (String designaiton : designations) {
+            inClause.value(designaiton);
+        }
+        criteriaQuery.select(root)
+            .where(inClause);
+        TypedQuery<DeptEmployee> query = entityManager.createQuery(criteriaQuery);
+        return query.getResultList();
+    }
+
+    @Override
+    public List<DeptEmployee> filterbyDesignationUsingExpression(List<String> designations) {
+        CriteriaQuery<DeptEmployee> criteriaQuery = createCriteriaQuery(DeptEmployee.class);
+        Root<DeptEmployee> root = criteriaQuery.from(DeptEmployee.class);
+        criteriaQuery.select(root)
+            .where(root.get("designation")
+                .in(designations));
+        TypedQuery<DeptEmployee> query = entityManager.createQuery(criteriaQuery);
+        return query.getResultList();
+    }
+
+    @Override
+    public List<DeptEmployee> searchByDepartmentQuery(String searchKey) {
+        CriteriaQuery<DeptEmployee> criteriaQuery = createCriteriaQuery(DeptEmployee.class);
+        Root<DeptEmployee> emp = criteriaQuery.from(DeptEmployee.class);
+
+        Subquery<Department> subquery = criteriaQuery.subquery(Department.class);
+        Root<Department> dept = subquery.from(Department.class);
+        subquery.select(dept)
+            .distinct(true)
+            .where(criteriaBuilder.like(dept.get("name"), new StringBuffer("%").append(searchKey)
+                .append("%")
+                .toString()));
+
+        criteriaQuery.select(emp)
+            .where(criteriaBuilder.in(emp.get("department"))
+                .value(subquery));
+
+        TypedQuery<DeptEmployee> query = entityManager.createQuery(criteriaQuery);
+        return query.getResultList();
+    }
+    
+    private <T> CriteriaQuery<T> createCriteriaQuery(Class<T> klass) {
+        return criteriaBuilder.createQuery(klass);
+    }
+
+}

persistence-modules/hibernate5/src/test/java/com/baeldung/hibernate/jpacriteriabuilder/EmployeeSearchServiceIntegrationTest.java

@@ -0,0 +1,122 @@
+package com.baeldung.hibernate.jpacriteriabuilder;
+
+import static org.hamcrest.MatcherAssert.assertThat;
+import static org.hamcrest.collection.IsIterableContainingInAnyOrder.containsInAnyOrder;
+import static org.junit.Assert.assertEquals;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.stream.Collectors;
+
+import javax.persistence.EntityManager;
+
+import org.hibernate.HibernateException;
+import org.hibernate.Session;
+import org.junit.After;
+import org.junit.Before;
+import org.junit.Test;
+
+import com.baeldung.hibernate.HibernateUtil;
+import com.baeldung.hibernate.entities.Department;
+import com.baeldung.hibernate.entities.DeptEmployee;
+import com.baeldung.hibernate.jpacriteriabuilder.service.EmployeeSearchService;
+import com.baeldung.hibernate.jpacriteriabuilder.service.EmployeeSearchServiceImpl;
+
+public class EmployeeSearchServiceIntegrationTest {
+
+    private EntityManager entityManager;
+    private EmployeeSearchService searchService;
+    private Session session;
+
+    @Before
+    public final void setup() throws HibernateException, IOException {
+        session = HibernateUtil.getSessionFactory()
+            .openSession();
+        entityManager = session.getEntityManagerFactory()
+            .createEntityManager();
+        searchService = new EmployeeSearchServiceImpl(entityManager);
+
+        entityManager.getTransaction()
+            .begin();
+        Department department = new Department("Pre Sales");
+        DeptEmployee employee = new DeptEmployee("John Smith", "001", "Manager", department);
+        entityManager.persist(department);
+        entityManager.persist(employee);
+        employee = new DeptEmployee("Ian Evans", "002", "Associate", department);
+        entityManager.persist(department);
+        entityManager.persist(employee);
+        department = new Department("Copporate Sales");
+        employee = new DeptEmployee("Robert Carter", "003", "Manager", department);
+        entityManager.persist(department);
+        entityManager.persist(employee);
+        employee = new DeptEmployee("John Carter", "004", "Senior Manager", department);
+        entityManager.persist(employee);
+        employee = new DeptEmployee("David Guetta", "009", "Associate", department);
+        entityManager.persist(department);
+        entityManager.persist(employee);
+        department = new Department("Post Sales");
+        employee = new DeptEmployee("Robert Jonas", "005", "Director", department);
+        entityManager.persist(department);
+        entityManager.persist(employee);
+        employee = new DeptEmployee("John Ferros", "006", "Junior Associate", department);
+        entityManager.persist(department);
+        entityManager.persist(employee);
+        department = new Department("Client Support");
+        employee = new DeptEmployee("Robert Mcclements", "007", "Director", department);
+        entityManager.persist(department);
+        entityManager.persist(employee);
+        employee = new DeptEmployee("Peter Parker", "008", "Manager", department);
+        entityManager.persist(department);
+        entityManager.persist(employee);
+
+    }
+
+    @After
+    public final void teardown() {
+        entityManager.getTransaction()
+            .rollback();
+        entityManager.close();
+    }
+
+    @Test
+    public final void givenCriteriaQuery_whenSearchedUsingCriteriaBuilderWithListofAuthors_thenResultIsFilteredByAuthorNames() {
+        List<String> designations = new ArrayList<String>() {
+            {
+                add("Manager");
+                add("Senior Manager");
+                add("Director");
+            }
+        };
+        List<DeptEmployee> result = searchService.filterbyDesignationUsingCriteriaBuilder(designations);
+        assertEquals("Number of Employees does not match with expected.", 6, result.size());
+        assertThat(result.stream()
+            .map(DeptEmployee::getDesignation)
+            .distinct()
+            .collect(Collectors.toList()), containsInAnyOrder(designations.toArray()));
+    }
+
+    @Test
+    public final void givenCriteriaQuery_whenSearchedUsingExpressionWithListofAuthors_thenResultIsFilteredByAuthorNames() {
+        List<String> designations = new ArrayList<String>() {
+            {
+                add("Manager");
+                add("Senior Manager");
+                add("Director");
+            }
+        };
+        List<DeptEmployee> result = searchService.filterbyDesignationUsingExpression(designations);
+        assertEquals("Number of Employees does not match with expected.", 6, result.size());
+        assertThat(result.stream()
+            .map(DeptEmployee::getDesignation)
+            .distinct()
+            .collect(Collectors.toList()), containsInAnyOrder(designations.toArray()));
+    }
+
+    @Test
+    public final void givenCriteriaQuery_whenSearchedDepartmentLike_thenResultIsFilteredByDepartment() {
+        List<DeptEmployee> result = searchService.searchByDepartmentQuery("Sales");
+        assertEquals("Number of Employees does not match with expected.", 7, result.size());
+        // assertThat(result.stream().map(DeptEmployee::getDesignation).distinct().collect(Collectors.toList()), containsInAnyOrder(designations.toArray()));
+    }
+}