ro4 / spel-validation

import org.springframework.beans.BeansException;

import org.springframework.beans.factory.BeanFactory;

import org.springframework.beans.factory.BeanFactoryAware;

import org.springframework.context.expression.BeanFactoryResolver;

import org.springframework.expression.spel.standard.SpelExpressionParser;

import org.springframework.expression.spel.support.StandardEvaluationContext;

import org.springframework.util.ObjectUtils;

import org.springframework.util.StringUtils;

import javax.validation.ConstraintValidator;

import javax.validation.ConstraintValidatorContext;

public class SpELValidator implements ConstraintValidator<SpELAssert, Object>, BeanFactoryAware {

    private static final SpelExpressionParser PARSER = new SpelExpressionParser();

    private String expression;

    private StandardEvaluationContext spELCtx;

    private BeanFactory beanFactory;

    private String alias;

    private String message;

    private String reportOn;

    @Override

    public void initialize(SpELAssert anno) {

        if (!ObjectUtils.isEmpty(anno.expression())) {

            expression = StringUtils.arrayToDelimitedString(anno.expression(), " ");

        } else if (!ObjectUtils.isEmpty(anno.value())) {

            expression = anno.value();

        }

        this.spELCtx = new StandardEvaluationContext();

        spELCtx.setBeanResolver(new BeanFactoryResolver(beanFactory));

        this.alias = anno.alias();

        this.message = anno.message();

        this.reportOn = anno.reportOn();

    }

    @Override

    public boolean isValid(Object value, ConstraintValidatorContext context) {

        spELCtx.setVariable(alias, value);

        boolean result = Boolean.TRUE.equals(PARSER.parseExpression(expression).getValue(spELCtx, Boolean.TYPE));

        if (!result && !reportOn.isEmpty()) {

            context.disableDefaultConstraintViolation();

            context.buildConstraintViolationWithTemplate(message).addPropertyNode(reportOn).addConstraintViolation();

        }

        return result;

    }

}