BAEL-2520 code changes done (#6446)

persistence-modules/spring-data-jpa/src/main/java/com/baeldung/dao/repositories/CustomItemRepository.java

@@ -1,5 +1,7 @@
 package com.baeldung.dao.repositories;
 
+import java.util.List;
+
 import org.springframework.stereotype.Repository;
 
 import com.baeldung.domain.Item;
@@ -12,4 +14,8 @@ public interface CustomItemRepository {
     Item findItemById(Long id);
 
     void findThenDelete(Long id);
+
+    List<Item> findItemsByColorAndGrade();
+
+    List<Item> findItemByColorOrGrade();
 }

persistence-modules/spring-data-jpa/src/main/java/com/baeldung/dao/repositories/impl/CustomItemRepositoryImpl.java

@@ -1,12 +1,18 @@
 package com.baeldung.dao.repositories.impl;
 
+import java.util.List;
+
 import javax.persistence.EntityManager;
+import javax.persistence.criteria.CriteriaBuilder;
+import javax.persistence.criteria.CriteriaQuery;
+import javax.persistence.criteria.Predicate;
+import javax.persistence.criteria.Root;
 
 import org.springframework.beans.factory.annotation.Autowired;
 import org.springframework.stereotype.Repository;
 
-import com.baeldung.domain.Item;
 import com.baeldung.dao.repositories.CustomItemRepository;
+import com.baeldung.domain.Item;
 
 @Repository
 public class CustomItemRepositoryImpl implements CustomItemRepository {
@@ -29,4 +35,54 @@ public class CustomItemRepositoryImpl implements CustomItemRepository {
         final Item item = entityManager.find(Item.class, id);
         entityManager.remove(item);
     }
+
+    @Override
+    public List<Item> findItemsByColorAndGrade() {
+
+        CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
+        CriteriaQuery<Item> criteriaQuery = criteriaBuilder.createQuery(Item.class);
+        Root<Item> itemRoot = criteriaQuery.from(Item.class);
+
+        Predicate predicateForBlueColor = criteriaBuilder.equal(itemRoot.get("color"), "blue");
+        Predicate predicateForRedColor = criteriaBuilder.equal(itemRoot.get("color"), "red");
+        Predicate predicateForColor = criteriaBuilder.or(predicateForBlueColor, predicateForRedColor);
+
+        Predicate predicateForGradeA = criteriaBuilder.equal(itemRoot.get("grade"), "A");
+        Predicate predicateForGradeB = criteriaBuilder.equal(itemRoot.get("grade"), "B");
+        Predicate predicateForGrade = criteriaBuilder.or(predicateForGradeA, predicateForGradeB);
+
+        // final search filter
+        Predicate finalPredicate = criteriaBuilder.and(predicateForColor, predicateForGrade);
+
+        criteriaQuery.where(finalPredicate);
+
+        List<Item> items = entityManager.createQuery(criteriaQuery)
+            .getResultList();
+        return items;
+    }
+
+    @Override
+    public List<Item> findItemByColorOrGrade() {
+
+        CriteriaBuilder criteriaBuilder = entityManager.getCriteriaBuilder();
+        CriteriaQuery<Item> criteriaQuery = criteriaBuilder.createQuery(Item.class);
+        Root<Item> itemRoot = criteriaQuery.from(Item.class);
+
+        Predicate predicateForBlueColor = criteriaBuilder.equal(itemRoot.get("color"), "red");
+        Predicate predicateForGradeA = criteriaBuilder.equal(itemRoot.get("grade"), "D");
+        Predicate predicateForBlueColorAndGradeA = criteriaBuilder.and(predicateForBlueColor, predicateForGradeA);
+
+        Predicate predicateForRedColor = criteriaBuilder.equal(itemRoot.get("color"), "blue");
+        Predicate predicateForGradeB = criteriaBuilder.equal(itemRoot.get("grade"), "B");
+        Predicate predicateForRedColorAndGradeB = criteriaBuilder.and(predicateForRedColor, predicateForGradeB);
+
+        // final search filter
+        Predicate finalPredicate = criteriaBuilder.or(predicateForBlueColorAndGradeA, predicateForRedColorAndGradeB);
+
+        criteriaQuery.where(finalPredicate);
+
+        List<Item> items = entityManager.createQuery(criteriaQuery)
+            .getResultList();
+        return items;
+    }
 }