[JAVA-30352] Move code of article Use Criteria Queries to spring-data-jpa-query-2 (#16230)

persistence-modules/spring-data-jpa-query-2/src/main/java/com/baeldung/criteriaquery/Book.java

@@ -0,0 +1,57 @@
+package com.baeldung.criteriaquery;
+
+import jakarta.persistence.Entity;
+import jakarta.persistence.GeneratedValue;
+import jakarta.persistence.Id;
+import org.springframework.data.jpa.domain.Specification;
+
+@Entity
+public class Book {
+
+    @Id
+    @GeneratedValue
+    private Long id;
+    private String title;
+    private String author;
+
+    public Book(String title, String author) {
+        this.title = title;
+        this.author = author;
+    }
+
+    public Book() {
+    }
+
+    public Long getId() {
+        return id;
+    }
+
+    public void setId(Long id) {
+        this.id = id;
+    }
+
+    public String getTitle() {
+        return title;
+    }
+
+    public void setTitle(String title) {
+        this.title = title;
+    }
+
+    public String getAuthor() {
+        return author;
+    }
+
+    public void setAuthor(String author) {
+        this.author = author;
+    }
+
+    static Specification<Book> hasAuthor(String author) {
+        return (book, cq, cb) -> cb.equal(book.get("author"), author);
+    }
+
+    static Specification<Book> titleContains(String title) {
+        return (book, cq, cb) -> cb.like(book.get("title"), "%" + title + "%");
+    }
+
+}

persistence-modules/spring-data-jpa-query-2/src/main/java/com/baeldung/criteriaquery/BookRepository.java

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+package com.baeldung.criteriaquery;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.data.jpa.repository.JpaSpecificationExecutor;
+import org.springframework.stereotype.Repository;
+
+@Repository
+interface BookRepository extends JpaRepository<Book, Long>, BookRepositoryCustom, JpaSpecificationExecutor<Book> {
+}

persistence-modules/spring-data-jpa-query-2/src/main/java/com/baeldung/criteriaquery/BookRepositoryCustom.java

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+package com.baeldung.criteriaquery;
+
+import java.util.List;
+
+interface BookRepositoryCustom {
+
+    List<Book> findBooksByAuthorNameAndTitle(String authorName, String title);
+
+}

persistence-modules/spring-data-jpa-query-2/src/main/java/com/baeldung/criteriaquery/BookRepositoryImpl.java

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+package com.baeldung.criteriaquery;
+
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.criteria.CriteriaBuilder;
+import jakarta.persistence.criteria.CriteriaQuery;
+import jakarta.persistence.criteria.Predicate;
+import jakarta.persistence.criteria.Root;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.stereotype.Repository;
+
+import java.util.ArrayList;
+import java.util.List;
+
+@Repository
+public class BookRepositoryImpl implements BookRepositoryCustom {
+
+    @Autowired
+    private EntityManager em;
+
+    @Override
+    public List<Book> findBooksByAuthorNameAndTitle(String authorName, String title) {
+        CriteriaBuilder cb = em.getCriteriaBuilder();
+        CriteriaQuery<Book> cq = cb.createQuery(Book.class);
+
+        Root<Book> book = cq.from(Book.class);
+        List<Predicate> predicates = new ArrayList<>();
+
+        if (authorName != null) {
+            predicates.add(cb.equal(book.get("author"), authorName));
+        }
+        if (title != null) {
+            predicates.add(cb.like(book.get("title"), "%" + title + "%"));
+        }
+        cq.where(predicates.toArray(new Predicate[0]));
+
+        return em.createQuery(cq).getResultList();
+    }
+
+}

persistence-modules/spring-data-jpa-query-2/src/test/java/com/baeldung/criteriaquery/CriteriaQueryIntegrationTest.java

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+package com.baeldung.criteriaquery;
+
+import jakarta.persistence.EntityManager;
+import jakarta.persistence.PersistenceContext;
+import org.junit.Before;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.autoconfigure.orm.jpa.DataJpaTest;
+import org.springframework.test.context.junit4.SpringRunner;
+
+import java.util.List;
+
+import static com.baeldung.criteriaquery.Book.hasAuthor;
+import static com.baeldung.criteriaquery.Book.titleContains;
+import static org.junit.Assert.assertEquals;
+import static org.springframework.data.jpa.domain.Specification.where;
+
+@DataJpaTest(showSql = false)
+@RunWith(SpringRunner.class)
+public class CriteriaQueryIntegrationTest {
+
+    @PersistenceContext
+    private EntityManager entityManager;
+    @Autowired
+    private BookRepository repository;
+
+    @Before
+    public void before() {
+        entityManager.persist(new Book("title1", "author1"));
+        entityManager.persist(new Book("title2", "author2"));
+    }
+
+    @Test
+    public void givenAuthorAndTextInTitle_whenFindWithSpecification_ThenFound() {
+        List<Book> books = repository.findAll(where(hasAuthor("author1")).and(titleContains("1")));
+        assertEquals(1, books.size());
+        assertEquals("author1", books.get(0).getAuthor());
+        assertEquals("title1", books.get(0).getTitle());
+    }
+
+    @Test
+    public void givenAuthorAndTextInTitle_whenFindWithCriteriaQuery_ThenFound() {
+        List<Book> books = repository.findBooksByAuthorNameAndTitle("author2", "2");
+        assertEquals(1, books.size());
+        assertEquals("author2", books.get(0).getAuthor());
+        assertEquals("title2", books.get(0).getTitle());
+    }
+
+}