Bean Validation is a standard validation specification that allows us to easily validate domain objects by using a set of constraints declared in the form of annotations.
Step 1: install dependency
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-validation</artifactId>
</dependency>
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
<dependency>
<groupId>com.h2database</groupId>
<artifactId>h2</artifactId>
<scope>runtime</scope>
</dependency>
Step 2: codes
User.java
@Data
@AllArgsConstructor
@NoArgsConstructor
@Entity
public class User {
@Id
@GeneratedValue(strategy = GenerationType.AUTO)
private long id;
@NotBlank(message = "Name is mandatory")
private String name;
@NotBlank(message = "Email is mandatory")
private String email;
}
UserRepository.java
@Repository
public interface UserRepository extends CrudRepository<User, Long> {}
UserController.java
@RestController
public class UserController {
@PostMapping("/users")
ResponseEntity<String> addUser(@Valid @RequestBody User user) {
return ResponseEntity.ok("User is valid");
}
@ResponseStatus(HttpStatus.BAD_REQUEST)
@ExceptionHandler(MethodArgumentNotValidException.class)
public Map<String, String> handleValidationExceptions(MethodArgumentNotValidException ex) {
Map<String, String> errors = new HashMap<>();
ex.getBindingResult().getAllErrors().forEach((error) -> {
String fieldName = ((FieldError) error).getField();
String errorMessage = error.getDefaultMessage();
errors.put(fieldName, errorMessage);
});
return errors;
}
}
UserControllerTest.java
@RunWith(SpringRunner.class)
// Since we're only testing the web layer, we use the @WebMvcTest annotation
@WebMvcTest
@AutoConfigureMockMvc
public class UserControllerTest {
@MockBean
private UserRepository userRepository;
@Autowired
UserController userController;
@Autowired
private MockMvc mockMvc;
@Test
public void whenPostRequestToUsersAndValidUser_thenCorrectResponse() throws Exception {
MediaType textPlainUtf8 = new MediaType(MediaType.TEXT_PLAIN, Charset.forName("UTF-8"));
String user = "{\"name\": \"bob\", \"email\" : \"bob@domain.com\"}";
mockMvc.perform(MockMvcRequestBuilders.post("/users")
.content(user)
.contentType(MediaType.APPLICATION_JSON_VALUE))
.andExpect(MockMvcResultMatchers.status().isOk())
.andExpect(MockMvcResultMatchers.content()
.contentType(textPlainUtf8));
}
@Test
public void whenPostRequestToUsersAndInValidUser_thenCorrectResponse() throws Exception {
String user = "{\"name\": \"\", \"email\" : \"bob@domain.com\"}";
mockMvc.perform(MockMvcRequestBuilders.post("/users")
.content(user)
.contentType(MediaType.APPLICATION_JSON_VALUE))
.andExpect(MockMvcResultMatchers.status().isBadRequest())
.andExpect(MockMvcResultMatchers.jsonPath("$.name", Is.is("Name is mandatory")))
.andExpect(MockMvcResultMatchers.content()
.contentType(MediaType.APPLICATION_JSON_VALUE));
}
}