WithoutId.java

package nl.knaw.huygens.alexandria.endpoint.resource;

/*
 * #%L
 * alexandria-main
 * =======
 * Copyright (C) 2015 - 2017 Huygens ING (KNAW)
 * =======
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as
 * published by the Free Software Foundation, either version 3 of the
 * License, or (at your option) any later version.
 * 
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * 
 * You should have received a copy of the GNU General Public
 * License along with this program.  If not, see
 * <http://www.gnu.org/licenses/gpl-3.0.html>.
 * #L%
 */

import javax.validation.Constraint;
import javax.validation.ConstraintValidator;
import javax.validation.ConstraintValidatorContext;
import javax.validation.Payload;
import java.lang.annotation.ElementType;
import java.lang.annotation.Retention;
import java.lang.annotation.RetentionPolicy;
import java.lang.annotation.Target;

@Target({ElementType.FIELD, ElementType.PARAMETER})
@Retention(RetentionPolicy.RUNTIME)
@Constraint(validatedBy = WithoutId.Validator.class)
public @interface WithoutId {
  String message() default "{nl.knaw.huygens.alexandria.endpoint.resource.WithoutId.message}";

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

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

  class Validator implements ConstraintValidator<WithoutId, ResourcePrototype> {
    @Override
    public void initialize(WithoutId constraintAnnotation) {
      // nothing needed.
    }

    @Override
    public boolean isValid(ResourcePrototype prototype, ConstraintValidatorContext context) {
      return prototype == null || prototype.getId() == null;
    }
  }
}