Validators in Behaviour

[Rodolfo Hansen]

Where I work we were thinking of writing a library to support the hibernate
validator <http://www.hibernate.org/412.html> library...

The idea I had so far, was to make a behaviour, that can be mixed with a
PropertyModel..

Something like the attached code...

What do you guys think?

/*
 * Copyright 2008 Kindleit Technologies. All rights reserved. This file, all
 * proprietary knowledge and algorithms it details are the sole property of
 * Kindleit Technologies unless otherwise specified. The software this file
 * belong with is the confidential and proprietary information of Kindleit
 * Technologies. ("Confidential Information"). You shall not disclose such
 * Confidential Information and shall use it only in accordance with the terms
 * of the license agreement you entered into with Kindleit.
 */
package com.kindleit.wicketweb.behaviors;

import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import java.util.List;

import org.apache.wicket.Component;
import org.apache.wicket.behavior.AbstractBehavior;
import org.apache.wicket.markup.html.form.FormComponent;
import org.apache.wicket.model.PropertyModel;
import org.apache.wicket.validation.IValidator;
import org.hibernate.validator.NotEmpty;
import org.hibernate.validator.NotNull;

import com.kindleit.wicketweb.exceptions.WicketWebRuntimeException;
import com.kindleit.wicketweb.validators.Validators;

/**
 * This behavior adds validators to the components it binds to, based on the
 * Hibernate Validator annotations written in a property, which is specified by
 * a given [EMAIL PROTECTED] PropertyModel}.
 * @author [EMAIL PROTECTED]
 */
public class HibernateValidatorBehavior extends AbstractBehavior {

  /**
   *
   */
  private static final long serialVersionUID = 1L;

  /**
   * [EMAIL PROTECTED] PropertyModel} that provide access to the property getter method
   * that has the validations annotations.
   */
  private PropertyModel propertyModel;

  /**
   * Construct a [EMAIL PROTECTED] HibernateValidatorBehavior}.
   * @param propertyModel [EMAIL PROTECTED] PropertyModel} object that provide access to
   *          the property getter method that has the validations annotations.
   */
  public HibernateValidatorBehavior(final PropertyModel propertyModel) {
    super();
    this.propertyModel = propertyModel;
  }

  /**
   * Add a [EMAIL PROTECTED] IValidator} for each Hibernate Validator annotation written in
   * the property specified by [EMAIL PROTECTED] #getPropertyModel()}.
   * @see AbstractBehavior#bind(Component);
   */
  @Override
  public void bind(final Component component) {
    super.bind(component);
    if (component instanceof FormComponent) {
      final FormComponent formComponent = (FormComponent) component;

      final Method getter = getPropertyModel().getPropertyGetter();
      final Annotation[] annotations = getter.getAnnotations();

      addValidators(formComponent, annotations);

      if (isRequiredProperty(annotations)) {
        formComponent.setRequired(true);
      }

    } else {
      throw WicketWebRuntimeException
          .invalidComponentType(FormComponent.class);
    }
  }

  /**
   * Search for [EMAIL PROTECTED] NotNull} and [EMAIL PROTECTED] NotEmpty} annotations in a given
   * array.
   * @param annotations An array of [EMAIL PROTECTED] Annotation} objects.
   * @return true if [EMAIL PROTECTED] NotNull} of [EMAIL PROTECTED] NotEmpty} annotations are
   *         present.
   */
  public boolean isRequiredProperty(final Annotation[] annotations) {
    for (final Annotation anno : annotations) {
      if (anno instanceof NotNull || anno instanceof NotEmpty) {
        return true;
      }
    }
    return false;
  }

  /**
   * Creates [EMAIL PROTECTED] IValidator} objects according to the annotations, then add
   * the validators to a given [EMAIL PROTECTED] FormComponent}.
   * @param component a [EMAIL PROTECTED] FormComponent} object to which validators will be
   *          added.
   * @param annotations An array of [EMAIL PROTECTED] Annotation} objects.
   */
  public void addValidators(final FormComponent component,
      final Annotation[] annotations) {
    final List<IValidator> validators = Validators.create(annotations);
    for (final IValidator validator : validators) {
      component.add(validator);
    }
  }

  /**
   * Getter for the <tt>propertyModel</tt>.
   * @return the propertyModel
   */
  public PropertyModel getPropertyModel() {
    return propertyModel;
  }

  /**
   * Setter for the <tt>propertyModel</tt>.
   * @param propertyModel the propertyModel to set
   */
  public void setPropertyModel(final PropertyModel propertyModel) {
    this.propertyModel = propertyModel;
  }

}