Spring Bean Validation with configurable constraint values

Question

I'd like to make Java Bean Validation constraints configurable by Spring, possibly by using properties. An example:

class Pizza {

    @MaxGramsOfCheese(max = "${application.pizza.cheese.max-grams}")
    int gramsOfCheese;

}

I haven't been able to get this to work or find much documentation about this.

Is something like this even possible? I know that messages are configurable in a Validationmessages.properties file, so I'm hoping something similar is possible for constraint values.

Answer 1

In addition to @Madhu Bhat you can configure your ConstraintValidator class to read properties from Spring's Environment.

public class MaxGramsOfCheeseValidator implements ConstraintValidator<MaxGramsOfCheese, Integer> {

    @Autowired
    private Environment env;

    private int max;

    public void initialize(MaxGramsOfCheese constraintAnnotation) {
        this.max = Integer.valueOf(env.resolvePlaceholders(constraintAnnotation.max()));
    }

    @Override
    public boolean isValid(Integer value, ConstraintValidatorContext context) {
        return value != null && value <= this.max;
    }

}

Thus you can use @MaxGramsOfCheese annotation on different fields with different parameters which may be more appropriate in your case.

class Pizza {

    @MaxGramsOfCheese(max = "${application.pizza.cheddar.max-grams}")
    int gramsOfCheddar;

    @MaxGramsOfCheese(max = "${application.pizza.mozerella.max-grams}")
    int gramsOfMozerella;

}