FormAutoValidatingBehavior.java

/**
 * Copyright (C) 2012 Michal Wegrzyn <bend-up@users.sourceforge.net>
 * Licensed under The MIT license.
 * You can use this file as long as you retain the above copyright notice.
 */
import org.apache.wicket.AttributeModifier;
import org.apache.wicket.Component;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.ajax.form.AjaxFormSubmitBehavior;
import org.apache.wicket.feedback.IFeedback;
import org.apache.wicket.markup.html.form.Form;
import org.apache.wicket.markup.html.form.FormComponent;
import org.apache.wicket.util.time.Duration;
import org.apache.wicket.util.visit.IVisit;
import org.apache.wicket.util.visit.IVisitor;

/**
 * Behaviour which automatically refreshes feedback panels,
 * checks whether form components are valid and marks them
 * with appropriate css class.
 *
 * @author Michal Wegrzyn
 *
 */
public class FormAutoValidatingBehavior extends AjaxFormSubmitBehavior {

	private static final long serialVersionUID = 1L;
	private static final Duration VALIDATION_THROTTLE = Duration.NONE;

	public FormAutoValidatingBehavior(Form<?> form ) {
		this( form, "onchange", VALIDATION_THROTTLE );
	}

	public FormAutoValidatingBehavior(Form<?> form, String event, Duration throttleDelay ) {
		super( form, event );

		if ( throttleDelay != null ) {
			setThrottleDelay( throttleDelay );
		}
	}

	/**
	 * Adds this behavior to all form components of the specified form
	 *
	 * @param form
	 * @param event
	 * @param throttleDelay
	 */
	public static void addToAllFormComponents(final Form<?> form, final String event,
			final Duration throttleDelay, final boolean recurse) {

		form.visitChildren(FormComponent.class,	new IVisitor<Component, Void>() {

			public void component( final Component component, final IVisit<Void> visit ) {

				FormAutoValidatingBehavior behavior = new FormAutoValidatingBehavior(	form, event, throttleDelay );

				component.add( behavior );

				if ( !recurse ) {
					visit.dontGoDeeper();
				}
			}

		});
	}

	@Override
	protected void onSubmit( AjaxRequestTarget target ) {

		addVisibleFeedbacks( target );
		onUpdate( target, isFormValid() );
		markFields( target );
	}

	@Override
	protected void onError(AjaxRequestTarget target) {

		addVisibleFeedbacks( target );
		onUpdate( target, isFormValid() );
		markFields( target );
	}

	/**
	 * Action executed during update on field.
	 * @param target
	 * @param isFormValid Indicates whether all form component are valid
	 */
	protected void onUpdate( AjaxRequestTarget target, boolean isFormValid ) {
	}

	/**
	 * Performs check on all form's fields and marks every with appropriate css class.
	 * @param target
	 */
	protected void markFields( final AjaxRequestTarget target ) {

		getForm().visitChildren(FormComponent.class, new IVisitor<Component, Void>() {

			public void component( final Component component, final IVisit<Void> visit ) {

				FormComponent<?> formComponent = (FormComponent<?>) component;

				if ( component.isVisibleInHierarchy() ) {
					component.add( new AttributeModifier( "class", "component-" + ( formComponent.isValid() ? "valid" : "invalid" ) ) );
					target.add( component );
				}
			}
		});
	}

	/**
	 * Performs check on all form's fields whether are they all valid.
	 */
	private boolean isFormValid() {

		Boolean result = getForm().visitChildren(FormComponent.class, new IVisitor<Component, Boolean>() {

			public void component( final Component component, final IVisit<Boolean> visit ) {

				FormComponent<?> formComponent = (FormComponent<?>) component;

				if ( !formComponent.isValid() ) {
					visit.stop( Boolean.FALSE );
				}

			}

		});

		return result == null || result;
	}

	/**
	 * Refreshes visible feedback components.
	 * @param target
	 */
	private void addVisibleFeedbacks( final AjaxRequestTarget target ) {

		getComponent().getPage().visitChildren( IFeedback.class, new IVisitor<Component, Void>() {
			@Override
			public void component( Component component, IVisit<Void> visit ) {
				if ( component.isVisibleInHierarchy() ) {
					target.add( component );
				}
			}
		} );
	}

}