Spring JDBC: JdbcClient
Starting from Spring Boot 3.2, JdbcClient is available as a modern and fluent API for database operations,
providing an alternative to the traditional JdbcTemplate. It offers a more readable and concise way to interact
with databases while retaining the robust foundation of JDBC.
In this tutorial, we will explore how to perform CRUD operations using JdbcClient and verify its behavior using
integration tests powered by Testcontainers.
Using JdbcClient
First, we will define a simple User record to represent our domain model.
public record User(Long id, String name, String username, String email) {
}Next, let’s create our repository. We will use JdbcClient to implement findAll, findById, and save operations.
@Repository
public class UserRepository {
private final JdbcClient jdbcClient;
public UserRepository(JdbcClient jdbcClient) {
this.jdbcClient = jdbcClient;
}
public List<User> findAll() {
return jdbcClient.sql("SELECT id, name, username, email FROM users")
.query(User.class)
.list();
}
public Optional<User> findById(Long id) {
return jdbcClient.sql("SELECT id, name, username, email FROM users WHERE id = :id")
.param("id", id)
.query(User.class)
.optional();
}
public void save(User user) {
jdbcClient.sql("INSERT INTO users (id, name, username, email) VALUES (:id, :name, :username, :email)")
.param("id", user.id())
.param("name", user.name())
.param("username", user.username())
.param("email", user.email())
.update();
}
}As seen in the snippet above, the syntax of JdbcClient makes query binding and result mapping highly readable. We use the .param() method for named parameters, and mapping a row to our User record is effortlessly handled by .query(User.class).
Verifying with Testcontainers
Now we will test our repository against a real PostgreSQL database, ensuring all queries are working correctly.
@DataJdbcTest
@Testcontainers
@Import(UserRepository.class)
class UserRepositoryTests {
@Container
@ServiceConnection
private static final PostgreSQLContainer<?> postgres = new PostgreSQLContainer<>("postgres:16-alpine");
@Autowired
private UserRepository repository;
private static final List<User> USERS = List.of(
new User(1L, "Rashidi Zin", "rashidi.zin", "[email protected]"),
new User(2L, "Zaid Zin", "zaid.zin", "[email protected]")
);
@BeforeEach
void setUp() {
USERS.forEach(repository::save);
}
@Test
void findAll_ShouldReturnAllUsers() {
List<User> users = repository.findAll();
assertThat(users).hasSize(2)
.containsExactlyInAnyOrderElementsOf(USERS);
}
@Test
void findById_ShouldReturnUser_WhenIdExists() {
Optional<User> user = repository.findById(1L);
assertThat(user).isPresent().contains(USERS.get(0));
}
@Test
void findById_ShouldReturnEmpty_WhenIdDoesNotExist() {
Optional<User> user = repository.findById(999L);
assertThat(user).isEmpty();
}
}Using @DataJdbcTest, Spring auto-configures a testing environment dedicated to JDBC-based applications. Combined with @ServiceConnection from Spring Boot, connecting to Testcontainers becomes trivial, requiring no explicit jdbc property configurations.
The full implementation of this tutorial can be found on GitHub.