Validate request with List<Integer> as a field with javax.validation

Question

I am using javax.validation for validating request in an API developed using spring.

I have to validate List<Integer> so that all values must be a positive number and size of the list must be exactly equal to some fix number e.g. 2.

public class RequestPoJo {

    private List<Integer> values;

}   

Valid request should be [ 1,2]

Invalid request should be [-1,2] or [1,2,3]

Answer 1

EDIT:

Just realized how you want to get your payload. In that case I think best would be to write your own constraint validator (annotation):

Annotation:

import javax.validation.Constraint;
import javax.validation.Payload;
import javax.validation.constraints.NotNull;
import javax.validation.constraints.Size;
import java.lang.annotation.Documented;
import java.lang.annotation.Retention;
import java.lang.annotation.Target;

import static java.lang.annotation.ElementType.ANNOTATION_TYPE;
import static java.lang.annotation.ElementType.FIELD;
import static java.lang.annotation.ElementType.METHOD;
import static java.lang.annotation.ElementType.PARAMETER;
import static java.lang.annotation.RetentionPolicy.RUNTIME;

@NotNull
@Size(min = 2, max = 2)
@Target( { METHOD, FIELD, ANNOTATION_TYPE, PARAMETER})
@Retention(RUNTIME)
@Constraint(validatedBy = {ValidRequestArrayValidator.class})
@Documented
public @interface ValidRequestArray {

        String message() default "{com.mycompany.constraints.ValidRequestArray}";

        Class<?>[] groups() default {};

        Class<? extends Payload>[] payload() default {};
}

Validator:

import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import java.util.List;

public class ValidRequestArrayValidator implements ConstraintValidator<ValidRequestArray, List<Integer>> {
    @Override
    public boolean isValid(List<Integer> value, ConstraintValidatorContext context) {
        return value.stream().noneMatch(n -> n < 0);
    }
}

RestController:

@RestController
@Validated
public class TestController  

    
    @RequestMapping("/test")
    void test(
            @RequestBody
            @ValidRequestArray
                    List<Integer> values) throws JsonProcessingException {
        System.out.println(new ObjectMapper().writeValueAsString(values));
    }
}