Spring boot post request model validation - spring-mvc

Question

What is recommended/best way to validate the post request DTO bean ?
If validation failed I need to send customized error message like
{
"code": "invalid_fields",
"fields": {
"email": "Required",
"password": "Required",
}
}
DTO model
public class SignUpRequest {
#JsonProperty("email")
String email;
#JsonProperty("password")
String password;
public Result validate(){
}
}
controller
#PostMapping(value = "/register")
public ResponseEntity<Object> signupRider(#RequestBody SignUpRequest signUpRequest) {
Result result = signUpRequest.validate();
return new ResponseEntity<>(x, HttpStatus.OK);
}
SignUpRequest DTO has the method validate.
What is the spring way of doing the validation ?
Thanks.

Answer 1

You can use the following technique.
add the following dependencies in your gradle/maven file
compile "javax.validation:validation-api:2.0.1.Final"
compile "org.hibernate.validator:hibernate-validator:6.0.9.Final"
Hibernate-validator is implementation of validation-api 2.0
Add Validated annotation to your controller class
import org.springframework.validation.annotation.Validated;
#RestController
#RequestMapping(value = "/contact")
#Validated
public class ContactController{
}
Add Valid annotation to your method parameter
import org.springframework.http.HttpStatus;
import org.springframework.http.ResponseEntity;
import org.springframework.validation.annotation.Validated;
import org.springframework.web.bind.annotation.PostMapping;
import org.springframework.web.bind.annotation.RequestBody;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;
import javax.validation.Valid;
#RestController
#RequestMapping(value = "/contact")
#Validated
public class ContactController{
#PostMapping(value = "/register")
public ResponseEntity<Object> signupRider(#Valid #RequestBody SignUpRequest signUpRequest) {
Result result = signUpRequest.validate();
return new ResponseEntity<>(x, HttpStatus.OK);
}
}
Add Validated annotation to your dto class
import org.springframework.validation.annotation.Validated;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Email;
#Validated
public class SignUpRequest {
#JsonProperty("email")
#Email
String email;
#JsonProperty("password")
#NotNull
String password;
}
Add ExceptionTranslator with RestControllerAdvice annotation
#RestControllerAdvice
public class ExceptionTranslator {
/**
* Exception handler for validation errors caused by method parameters #RequesParam, #PathVariable, #RequestHeader annotated with javax.validation constraints.
*/
#ExceptionHandler
protected ResponseEntity<?> handleConstraintViolationException(ConstraintViolationException exception) {
List<ApiError> apiErrors = new ArrayList<>();
for (ConstraintViolation<?> violation : exception.getConstraintViolations()) {
String value = (violation.getInvalidValue() == null ? null : violation.getInvalidValue().toString());
apiErrors.add(new ApiError(violation.getPropertyPath().toString(), value, violation.getMessage()));
}
return ResponseEntity.badRequest().body(apiErrors);
}
}
Create ApiError class
import com.fasterxml.jackson.annotation.JsonIgnore;
import lombok.AllArgsConstructor;
import lombok.Data;
import lombok.NoArgsConstructor;
#Data
#NoArgsConstructor
#AllArgsConstructor
public class ApiError {
#JsonIgnore
private int code;
private String field;
private String value;
private String message;
public ApiError(String message) {
this.message = message;
}
public ApiError(String field, String value, String message) {
this.field = field;
this.value = value;
this.message = message;
}
}
Now if password field is missed you'll see the following response structure:
[
{
"field": "password",
"message": "must be filled"
}
]
If you would like to use some custom logic to validate your fields you may use the following approach
Create specific annotation class
import javax.validation.Constraint;
import javax.validation.Payload;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;
import static java.lang.annotation.ElementType.CONSTRUCTOR;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.RetentionPolicy.RUNTIME;
#Constraint(validatedBy = ContactRequiredParametersValidator.class)
#Target({ METHOD, CONSTRUCTOR })
#Retention(RUNTIME)
#Documented
public #interface ContactRequiredParameters {
String message() default
"Email or phone must be filled";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
Create custom validator
import org.apache.commons.lang.StringUtils;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import javax.validation.constraintvalidation.SupportedValidationTarget;
import javax.validation.constraintvalidation.ValidationTarget;
#SupportedValidationTarget(ValidationTarget.PARAMETERS)
public class ContactRequiredParametersValidator implements ConstraintValidator<ContactRequiredParameters, Object[]> {
#Override
public boolean isValid(Object[] value,
ConstraintValidatorContext context) {
if (value[0] == null) {
return true;
}
if (!(value[0] instanceof SignUpRequest)) {
throw new IllegalArgumentException(
"Illegal method signature, expected two parameters of type LocalDate.");
}
SignUpRequest contact = (SignUpRequest) value[0];
return StringUtils.isNotEmpty(contact.getPassword());
}
}
add #ContactRequiredParameters annotation to your method in controller
#PostMapping(value = "/register")
#ContactRequiredParameters
public ResponseEntity<Object> signupRider(#Valid #RequestBody SignUpRequest signUpRequest)
That's all. Hope it helps

Answer 2

Spring boot supports validation out of the box using validation-api which is included with spring web mvc starter:
#RestController
#RequiredArgsConstructor
public class TestController {
#PutMapping(value = "/", consumes = APPLICATION_JSON_VALUE)
#ResponseStatus(NO_CONTENT)
public void test(#Valid #RequestBody final SignUpRequest params) {
...
}
}
You can annotate your SignUpRequest using annotations such as javax.validation.constraints.NotNull and other more complex ones.
the error messages can be customised with message properties or hard coded strings if i18n/l10n is of less interest to you.
Sample here: https://spring.io/guides/gs/validating-form-input/

Answer 3

If you want behaviour outside of the provided annotations you can write a custom annotation that can do that, e.g.
#Target({FIELD})
#Retention(RUNTIME)
#Constraint(validatedBy = NotPastValidator.class)
#Documented
public #interface NotPast {
String message() default "date must not be in the past";
Class<?>[] groups() default {};
Class<? extends Payload>[] payload() default {};
}
Then:
public class NotPastValidator implements ConstraintValidator<NotPast, LocalDate> {
#Override
public void initialize(final NotPast constraintAnnotation) {
// nothing to do.
}
#Override
public boolean isValid(final LocalDate value, final ConstraintValidatorContext context) {
// As the Bean Validation specification recommends, we consider null values as being valid.
return value == null || isDateNotPast(value);
}
private boolean isDateNotPast(final LocalDate value) {
return ...
}
}
And finally just annotate your field:
#NotPast
Of course this is just an example with some code I previously used, you'll need to adapt to your needs.
If you don't want to use the validator API at all you can equally just write your own code to programatically check and throw some type of custom exception when invalid. This can then be caught in the controller and you can send what ever response you want, e.g.
#RestController
public class PaymentController {
#PostMapping(value ="/", consumes = APPLICATION_JSON_VALUE)
public void makePayment(#RequestBody final PaymentParams params) {
// validationService.validate(params);
}
#ExceptionHandler(MyValidationException.class)
public ResponseEntity<ExceptionDto> paymentCardException(final MyValidationException e) {
return status(BAD_REQUEST)
.contentType(APPLICATION_JSON)
.body(new ExceptionDto(e.getMessage));
}
}
I'd say given the validation API is well supported by spring, to me it makes sense to apply declarative validations where possible when using this stack. Custom rules can be a little painful, but you can use a multi faceted approach with some annotation based and equally you can perform some more complex validations in your own service.

Answer 4

This is a custom validation.
#PostMapping
private ResponseEntity<?> addMessage(#RequestBody Message message) {
Map<String, String> response = new HashMap<>();
if (message.getInputMessage() == null || message.getInputMessage().equals("")) {
response.put("status", "E");
response.put("message", "input message can not be empty");
return ResponseEntity.ok(response);
}
int id = messageService.addMessage(message);
if (id <= 0) {
response.put("status", "E");
response.put("message", "add message has error");
return ResponseEntity.ok(response);
}
response.put("status", "S");
response.put("message", "success");
return ResponseEntity.ok(response);
}