CssFeedbackBehavior.java

package be.selckin.swu.validation;

import org.apache.wicket.Component;
import org.apache.wicket.behavior.AttributeAppender;
import org.apache.wicket.behavior.Behavior;
import org.apache.wicket.markup.html.form.Form;
import org.apache.wicket.markup.html.form.FormComponent;
import org.apache.wicket.model.AbstractReadOnlyModel;
import org.apache.wicket.util.visit.IVisit;
import org.apache.wicket.util.visit.IVisitor;

import static com.google.common.base.Preconditions.checkNotNull;

public class CssFeedbackBehavior extends Behavior {

    protected String validCssClass = "";
    protected String invalidCssClass = "error";

    @Override
    public void onConfigure(Component component) {
        super.onConfigure(component);
        if (component instanceof Form)
            ((Form<?>) component).visitFormComponents(new IVisitor<FormComponent<?>, Void>() {
                @Override
                public void component(FormComponent<?> formComponent, IVisit<Void> visit) {
                    formComponent.add(AttributeAppender.append("class", new ValidFormComponentROM(formComponent)));
                }
            });
    }

    public CssFeedbackBehavior setValidCssClass(String validCssClass) {
        this.validCssClass = checkNotNull(validCssClass);
        return this;
    }

    public CssFeedbackBehavior setInvalidCssClass(String invalidCssClass) {
        this.invalidCssClass = checkNotNull(invalidCssClass);
        return this;
    }

    public class ValidFormComponentROM extends AbstractReadOnlyModel<String> {
        private final FormComponent<?> formComponent;

        public ValidFormComponentROM(FormComponent<?> formComponent) {
            this.formComponent = formComponent;
        }

        @Override
        public String getObject() {
            return formComponent.isValid() ? validCssClass : invalidCssClass;
        }
    }
}