Add Article service and DAO with criteria-based search functionality

hibernate-project/src/main/java/com/humanbooster/dao/ArticleDao.java

@@ -1,17 +1,22 @@
 package com.humanbooster.dao;
 
 import com.humanbooster.model.Article;
+import jakarta.persistence.criteria.CriteriaBuilder;
+import jakarta.persistence.criteria.CriteriaQuery;
 import org.hibernate.Session;
 import org.hibernate.SessionFactory;
 
-public class ArticleDao extends GenericDaoImpl<Article,Long> {
+import java.util.List;
+import java.util.Optional;
+
+public class ArticleDao extends GenericDaoImpl<Article, Long> {
 
     public ArticleDao(SessionFactory sessionFactory) {
         super(sessionFactory, Article.class);
     }
 
     public Article findByAuthor(String author) {
-        try(Session session = sessionFactory.openSession()){
+        try (Session session = sessionFactory.openSession()) {
             session.beginTransaction();
             Article article = session.createQuery("FROM Article WHERE author = :author", Article.class)
                     .setParameter("author", author)
@@ -22,7 +27,7 @@ public class ArticleDao extends GenericDaoImpl<Article,Long> {
     }
 
     public Article findByTitle(String title) {
-        try(Session session = sessionFactory.openSession()){
+        try (Session session = sessionFactory.openSession()) {
             session.beginTransaction();
             Article article = session.createQuery("FROM Article WHERE title = :title", Article.class)
                     .setParameter("title", title)
@@ -31,4 +36,38 @@ public class ArticleDao extends GenericDaoImpl<Article,Long> {
             return article;
         }
     }
+
+    public List<Article> findByCriteria(String keyword, Long authorId) {
+
+        Optional<String> optKeyword = Optional.ofNullable(keyword);
+        Optional<Long> optAuthorId = Optional.ofNullable(authorId);
+
+        List<Article> articles;
+
+        try (Session session = sessionFactory.openSession()) {
+            session.beginTransaction();
+
+            CriteriaBuilder cb = session.getCriteriaBuilder();
+            CriteriaQuery<Article> query = cb.createQuery(Article.class);
+
+            var root = query.from(Article.class);
+
+            query.select(root);
+
+            optKeyword.ifPresent(s -> query.where(
+                    cb.like(
+                            cb.lower(
+                                    root.get("title")), "%" + s.toLowerCase() + "%")
+            ));
+
+            optAuthorId.ifPresent(l -> query.where(
+                    cb.equal(
+                            root.get("author"), l)
+
+            ));
+
+            articles = session.createQuery(query).getResultList();
+        }
+        return articles;
+    }
 }