BAEL-5263 : Access Entity Manager with Spring Boot and Spring Data (#11680)

* feat: entity manager with spring data

* fix typo

* fix: article and code review

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/customrepository/CustomRepositoryApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung.spring.data.persistence.customrepository;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class CustomRepositoryApplication {
+
+    public static void main(String[] args) {
+        SpringApplication.run(CustomRepositoryApplication.class, args);
+    }
+}

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/customrepository/model/User.java

@@ -0,0 +1,55 @@
+package com.baeldung.spring.data.persistence.customrepository.model;
+
+import javax.persistence.Entity;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import java.util.Objects;
+
+@Entity
+public class User {
+
+    @Id
+    @GeneratedValue
+    private Long id;
+    private String name;
+    private String email;
+
+    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 getEmail() {
+        return email;
+    }
+
+    public void setEmail(String email) {
+        this.email = email;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (this == o)
+            return true;
+        if (o == null || getClass() != o.getClass())
+            return false;
+        User user = (User) o;
+        return Objects.equals(id, user.id) && Objects.equals(name, user.name) && Objects.equals(email, user.email);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(id, name, email);
+    }
+}

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/customrepository/repository/CustomUserRepository.java

@@ -0,0 +1,9 @@
+package com.baeldung.spring.data.persistence.customrepository.repository;
+
+import com.baeldung.spring.data.persistence.customrepository.model.User;
+
+public interface CustomUserRepository {
+
+    User customFindMethod(Long id);
+
+}

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/customrepository/repository/CustomUserRepositoryImpl.java

@@ -0,0 +1,26 @@
+package com.baeldung.spring.data.persistence.customrepository.repository;
+
+import com.baeldung.spring.data.persistence.customrepository.model.User;
+
+import javax.annotation.PostConstruct;
+import javax.persistence.EntityManager;
+import javax.persistence.PersistenceContext;
+import java.util.Objects;
+
+public class CustomUserRepositoryImpl implements CustomUserRepository {
+
+    @PersistenceContext
+    private EntityManager entityManager;
+
+    @Override
+    public User customFindMethod(Long id) {
+        return (User) entityManager.createQuery("FROM User u WHERE u.id = :id")
+                .setParameter("id", id)
+                .getSingleResult();
+    }
+
+    @PostConstruct
+    public void postConstruct() {
+        Objects.requireNonNull(entityManager);
+    }
+}

persistence-modules/spring-data-jpa-repo-2/src/main/java/com/baeldung/spring/data/persistence/customrepository/repository/UserRepository.java

@@ -0,0 +1,10 @@
+package com.baeldung.spring.data.persistence.customrepository.repository;
+
+import com.baeldung.spring.data.persistence.customrepository.model.User;
+import org.springframework.data.jpa.repository.JpaRepository;
+import org.springframework.stereotype.Repository;
+
+@Repository
+public interface UserRepository extends JpaRepository<User, Long>, CustomUserRepository {
+
+}

persistence-modules/spring-data-jpa-repo-2/src/test/java/com/baeldung/spring/data/persistence/customrepository/CustomRepositoryUnitTest.java

@@ -0,0 +1,27 @@
+package com.baeldung.spring.data.persistence.customrepository;
+
+import com.baeldung.spring.data.persistence.customrepository.model.User;
+import com.baeldung.spring.data.persistence.customrepository.repository.UserRepository;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+@SpringBootTest(classes = CustomRepositoryApplication.class)
+class CustomRepositoryUnitTest {
+
+    @Autowired
+    private UserRepository userRepository;
+
+    @Test
+    void givenCustomRepository_whenInvokeCustomFindMethod_thenEntityIsFound() {
+        User user = new User();
+        user.setEmail("foo@gmail.com");
+        user.setName("userName");
+
+        User persistedUser = userRepository.save(user);
+
+        assertEquals(persistedUser, userRepository.customFindMethod(user.getId()));
+    }
+}