Spring Boot - Constraint Validator @Autowired field null

Question

@Autowired not working, Environment env is always null.

public class MyConstraintValidator implements ConstraintValidator<MyConstraint, String> {
  @Autowired
  private Environment env;

  @Override
  public void initialize(MyConstraint constraintAnnotation) {
     env.resolvePlaceholders(...));
  }

  @Override
  public boolean isValid(String string, ConstraintValidatorContext constraintValidatorContext) {
     return false;
  }
}

Otherwise if use a constructor with parameter Environment and assign it to local Environment env, with @Autowired on the constructor, it is not null. But then the initialize(...) method is not called.

What is the solution?

I'm sorry I didn't read the question good enough. You cannot use @Autowired. You have to create a constructor with an Enviroment as Parameter. — Simon Martinelli, May 13 '20 at 15:13
Hmm. With older Spring versions that didn't work but now I see that this should be possible: https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#validation-beanvalidation — Simon Martinelli, May 13 '20 at 15:18
If I use a constructor, somehow the initialize method is not called. I use Spring Boot 2.2.6 and JDK 14 — neblaz, May 13 '20 at 15:20
Provide the code in your question, not in an answer. Provide a [mcve]. — Savior, May 13 '20 at 15:56

score -1 · Answer 1 · answered May 13 '20 at 14:20

-1

MyConstraintValidator is not a Bean (ex. @Service, @Component) it can't Autowire other beans. If you need to access some properties from environment, there's a way to put them to static context through implementing EnvironmentAware

Spring Boot - Environment @Autowired throws NullPointerException

answered May 13 '20 at 14:20

Ermintar

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It might be a bean through `@Bean`? It doesn't have to be annotated with `@Component`. Also, how do you explain their claim that it works when they use a constructor? – Savior May 13 '20 at 15:03
@Savior, looks like spring raises beans for all ConstraintValidator classes via ConstraintValidatorFactory. Just checked a sample with Autowired as in the question above, worked without any issues – Ermintar May 13 '20 at 16:15
@neblaz, could you share MyConstraint class? I faced, that initialize block was not called unless MyConstraint contained groups & payload methods. – Ermintar May 13 '20 at 16:18
It is basically this example (marked as correct): https://stackoverflow.com/questions/56920934/spring-bean-validation-with-configurable-constraint-values – neblaz May 14 '20 at 06:19

score -1 · Answer 2 · answered May 13 '20 at 14:23

I can't use comments, but you can try referencing this answer about Spring Inversion of Control Container.

It looks like Spring doesn't know about your class, so it doesn't know to auto-inject Environment. You can try annotating it with Spring's @Component and see if that helps.

Spring Boot - Constraint Validator @Autowired field null

2 Answers2