@Autowired field is null

Question

Autowiring works everywhere in application except inside this custom validation annotation class where it is null when called from inside isValid() method.

javax.validation:validation-api: 2.0.1.Final
org.hibernate:hibernate-validator: 5.0.1.Final
spring: 5.1.4.RELEASE


@Component
public class ValidatorUniqueUsername implements ConstraintValidator<UniqueUsername, String> {
    @Autowired
    AccountService jpaAccountService;

    @Override
    public void initialize(UniqueUsername constraintAnnotation) { }

    @Override
    public boolean isValid(String username, ConstraintValidatorContext context) {
        return username != null && jpaAccountService.findByUsername(username) == null;
    }
}


@Entity
...
public class Account extends BaseEntity<Long> implements Serializable{
    @NotEmpty
    @UniqueUsername
    private String username;
}

@Configuration
    public class AppConfig implements AsyncConfigurer {
@Bean
public Validator validatorFactory() {
    return new LocalValidatorFactoryBean();
}
        @Bean
        public static LocalValidatorFactoryBean validatorFactory() {
            return new LocalValidatorFactoryBean();
        }

Possible duplicate of https://stackoverflow.com/questions/27526620/dependency-injection-in-jsr-303-constraint-validator-with-spring-fails — dur, Mar 19 '19 at 20:08
@JamieWhite Are you sure your component scan is finding your classes `AppConfig` and `ValidatorUniqueUsername`? — dur, Mar 19 '19 at 20:45

pirho · Answer 1 · 2019-03-19T20:09:06.287

Your custom annotation @UniqueUsername instantiates and calls your ValidatorUniqueUsername but it does not inject it even it is annotated with @Component.

And because of this none of the resources to be autowired in your ValidatorUniqueUsername will be injected.

You could try to add this to your @Configuration:

@Bean
public Validator validatorFactory() {
    return new LocalValidatorFactoryBean();
}

See more here (excerpt below):

In spring if we register LocalValidatorFactoryBean to bootstrap javax.validation.ValidatorFactory then custom ConstraintValidator classes are loaded as Spring Bean. That means we can have benefit of Spring's dependency injection in validator classes.

@JamieWhite I remember I had this working few days ago but I'll look at better time if there is some other conf that you are missing. — pirho, Mar 22 '19 at 08:14

@Autowired field is null

1 Answers1