Annotations from javax.validation.constraints not working

What configuration is needed to use annotations from javax.validation.constraints like @Size, @NotNull, etc.? Here's my code:

import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;

public class Person {
	  @NotNull
	  private String id;
	  
	  @Size(max = 3)
	  private String name;

      private int age;

	  public Person(String id, String name, int age) {
	    this.id = id;
	    this.name = name;
	    this.age = age;
	  }
}

When I try to use it in another class, validation doesn't work (i.e. the object is created without error):

Person P = new Person(null, "Richard3", 8229));

Why doesn't this apply constraints for id and name? What else do I need to do?

For JSR-303 bean validation to work in Spring, you need several things:

1. MVC namespace configuration for annotations: <mvc:annotation-driven />
2. The JSR-303 spec JAR: validation-api-1.0.0.GA.jar (looks like you already have that)
3. An implementation of the spec, such as Hibernate Validation, which appears to be the most commonly used example: hibernate-validator-4.1.0.Final.jar
4. In the bean to be validated, validation annotations, either from the spec JAR or from the implementation JAR (which you have already done)
5. In the handler you want to validate, annotate the object you want to validate with @Valid, and then include a BindingResult in the method signature to capture errors.

Example:

@RequestMapping("handler.do")
public String myHandler(@Valid @ModelAttribute("form") SomeFormBean myForm, BindingResult result, Model model) {
    if(result.hasErrors()) {
      ...your error handling...
    } else {
      ...your non-error handling....
    }
}

You should use Validator to check whether you class is valid.

Person person = ....;
ValidatorFactory factory = Validation.buildDefaultValidatorFactory();
validator = factory.getValidator();
Set<ConstraintViolation<Person>> violations = validator.validate(person);

Then, iterating violations set, you can find violations.

In my case, I was using spring boot version 2.3.0. When I changed my maven dependency to use 2.1.3 it worked.

<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>2.1.3.RELEASE</version>
	<relativePath /> <!-- lookup parent from repository -->
</parent>
<dependencies>
    <dependency>
        <groupId>javax.validation</groupId>
        <artifactId>validation-api</artifactId>
    </dependency>
</dependencies>

You would have to call a Validator on the Entity if you want to validate it. Then you will get a set of ConstraintViolationException, which basically show for which field/s of your Entity there is a constraint violation and what exactly was it. Maybe you can also share some of the code you expect to validate your entity.

An often used technique is to do validation in @PrePersist and rollback transaction if using multiple data modifications during transaction or do other actions when you get a validation exception.

Your code should go like this:

@PrePersist
public void prePersist(SomeEntity someEntity){
    Validator validator = Validation.buildDefaultValidatorFactory.getValidator();
    Set<ConstraintViolation<SomeEntity>> = validator.validate(someEntity);
    //do stuff with them, like notify client what was the wrong field, log them, or, if empty, be happy
}

You can also simply use @NonNull with the lombok library instead, at least for the @NotNull scenario. More details: https://projectlombok.org/api/lombok/NonNull.html

I come here some years after, and I could fix it thanks to atrain's comment above. In my case, I was missing @Valid in the API that receives the Object (a POJO in my case) that was annotated with @Size. It solved the issue.

I did not need to add any extra annotation, such as @Valid or @NotBlank to the variable annotated with @Size, just that constraint in the variable and what I mentioned in the API...

Pojo Class:

...
@Size(min = MIN_LENGTH, max = MAX_LENGTH);
private String exampleVar;
...

API Class:

...
public void exampleApiCall(@RequestBody @Valid PojoObject pojoObject){
  ...
}

Thanks and cheers

After the Version 2.3.0 the "spring-boot-strarter-test" (that included the NotNull/NotBlank/etc) is now "sprnig boot-strarter-validation"

Just change it from ....-test to ...-validation and it should work.

If not downgrading the version that you are using to 2.1.3 also will solve it.

You need to add @Valid to each member variable, which was also an object that contained validation constraints.

In my case the reason was the hibernate-validator version. Probably something is not supported in the newer version any more.

I changed:

<dependency>
    <groupId>org.hibernate</groupId>
    <artifactId>hibernate-validator</artifactId>
    <version>${hibernate-validator.version}</version>
</dependency>

I downgraded the version from 7.0.1.Final to 6.0.2.Final and this helped me.

in my case i had a custom class-level constraint that was not being called.

@CustomValidation // not called
public class MyClass {
    @Lob
    @Column(nullable = false)
    private String name;
}

as soon as i added a field-level constraint to my class, either custom or standard, the class-level constraint started working.

@CustomValidation // now it works. super.
public class MyClass {
    @Lob
    @Column(nullable = false)
    @NotBlank // adding this made @CustomValidation start working
    private String name;
}

seems like buggy behavior to me but easy enough to work around i guess

I also faced the same problem. Javax annotations ( @NotNull, @Valid) were not performing any validation. Their presence was not making any difference.

I have to use 'springboot-starter-validation' dependency to make the javax validations effective. Here is the related dependencies configuration. Also don't miss to add @Valid annotation on the Object you want to validate.

<parent>
	<groupId>org.springframework.boot</groupId>
	<artifactId>spring-boot-starter-parent</artifactId>
	<version>2.5.2</version>
	<relativePath/> <!-- lookup parent from repository -->
</parent>
.....
.....
<dependencies>
	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-web</artifactId>
	</dependency>

	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-validation</artifactId>
	</dependency>

	<dependency>
		<groupId>javax.validation</groupId>
		<artifactId>validation-api</artifactId>
	</dependency>

	<dependency>
		<groupId>org.springframework.boot</groupId>
		<artifactId>spring-boot-starter-test</artifactId>
		<scope>test</scope>
	</dependency>
 <dependencies>

Recently I faced the same. I upgraded hibernate-validator to ver 7.x but later I noticed this release note

> Hibernate Validator 7.0 is the reference implementation for Jakarta Bean Validation 3.0.
> The main change is that all the dependencies using javax. packages are now using jakarta.* packages.
> Upgrade to Hibernate Validator 7 is only recommended if you are moving to Jakarta EE 9.

My project should target java 8, so keeping javax.validation instead of switiching to jakarta.validation, I've had to downgrade to

<dependency>
  <groupId>org.hibernate.validator</groupId>
  <artifactId>hibernate-validator</artifactId>
  <version>6.0.2.Final</version>
</dependency>

So @Valid at service interface would work for only that object. If you have any more validations within the hierarchy of ServiceRequest object then you might to have explicitly trigger validations. So this is how I have done it:

public class ServiceRequestValidator {

      private static Validator validator;

      @PostConstruct
      public void init(){
         validator = Validation.buildDefaultValidatorFactory().getValidator();
      }

      public static <T> void validate(T t){
        Set<ConstraintViolation<T>> errors = validator.validate(t);
        if(CollectionUtils.isNotEmpty(errors)){
          throw new ConstraintViolationException(errors);
        }
     }

}

You need to have following annotations at the object level if you want to trigger validation for that object.

@Valid
@NotNull

for method parameters you can use Objects.requireNonNull() like this: test(String str) { Objects.requireNonNull(str); } But this is only checked at runtime and throws an NPE if null. It is like a preconditions check. But that might be what you are looking for.

Great answer from atrain, but maybe better solution to catch exceptions is to utilize own HandlerExceptionResolver and catch

@Override
public ModelAndView resolveException(
    HttpServletRequest aReq, 
    HttpServletResponse aRes,
    Object aHandler, 
    Exception anExc
){
    // ....
    if(anExc instanceof MethodArgumentNotValidException) // do your handle     error here
}

Then you're able to keep your handler as clean as possible. You don't need BindingResult, Model and SomeFormBean in myHandlerMethod anymore.

I came across this problem recently in a very similar situation: Met all requirements as the top-rated answer listed but still got the wrong result.

So I looked at my dependencies and found I was missing some of them. I corrected it by adding the missing dependencies.

I was using hibernate, the required dependencies were:

*Snapshot taken in class "Spring & Hibernate for Beginners" @ Udemy

If you are using lombok then, you can use @NonNull annotation insted. or Just add the javax.validation dependency in pom.xml file.

For those who have not been able to perform server-side validation through Hibernate validation dependency. Just remove Hibernate validator +javax validation dependency and add spring-boot-starter validation. It provides Hibernate Validator Internally, and it worked just fine for me.

Credits:- a comment from youtube.

By default javax validation in spring works for Rest controller method input variables. But for other places to use the same we have to annotate class containing @Valid annotation with @Validated class level annotation.

I was facing same issue with kafka listener and after that I annotated it with @Validated it started working.

@Component
@Log4j2
@Validated
public class KafkaMessageListeners {

    @KafkaListener(topics = "message_reprocessor", errorHandler = "validationErrorHandler")
    public void processMessage(@Payload @Valid CustomPojo payload,
                               @Header(KafkaHeaders.OFFSET) List<Long> offsets, Acknowledgment acknowledgment) {

    }

}

In my case i removed these lines

1-import javax.validation.constraints.NotNull;

2-import javax.validation.constraints.Size;

3- @NotNull

4- @Size(max = 3)