/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.wicket.ajax.markup.html;
import org.apache.wicket.ajax.AjaxEventBehavior;
import org.apache.wicket.ajax.AjaxRequestTarget;
import org.apache.wicket.ajax.attributes.AjaxRequestAttributes;
import org.apache.wicket.markup.ComponentTag;
import org.apache.wicket.markup.html.link.Link;
import org.apache.wicket.model.IModel;
/**
* An ajax link that will degrade to a normal request if ajax is not available or javascript is
* disabled.
*
* <p>
* If JavaScript is enabled then the registered JavaScript event 'click' handler will be used,
* otherwise the 'href' attribute if the markup element is an <a>, <area> or
* <link>. AjaxFallbackLink doesn't fallback if the markup element is none of the three above.
* </p>
*
* @since 1.2
*
* @author Igor Vaynberg (ivaynberg)
* @param <T>
* type of model object
*/
public abstract class AjaxFallbackLink<T> extends Link<T> implements IAjaxLink
{
/** */
private static final long serialVersionUID = 1L;
/**
* Construct.
*
* @param id
*/
public AjaxFallbackLink(final String id)
{
this(id, null);
}
/**
* Construct.
*
* @param id
* @param model
*/
public AjaxFallbackLink(final String id, final IModel<T> model)
{
super(id, model);
}
@Override
protected void onInitialize()
{
super.onInitialize();
add(newAjaxEventBehavior("click"));
}
/**
* @param event
* the name of the default event on which this link will listen to
* @return the ajax behavior which will be executed when the user clicks the link
*/
protected AjaxEventBehavior newAjaxEventBehavior(String event)
{
return new AjaxEventBehavior(event)
{
private static final long serialVersionUID = 1L;
@Override
protected void onEvent(AjaxRequestTarget target)
{
onClick(target);
}
/**
*
* @see org.apache.wicket.ajax.AjaxEventBehavior#onComponentTag(org.apache.wicket.markup.ComponentTag)
*/
@Override
protected void onComponentTag(ComponentTag tag)
{
// only render handler if link is enabled
if (isEnabledInHierarchy())
{
super.onComponentTag(tag);
}
}
@Override
protected void updateAjaxAttributes(AjaxRequestAttributes attributes)
{
super.updateAjaxAttributes(attributes);
attributes.setPreventDefault(true);
AjaxFallbackLink.this.updateAjaxAttributes(attributes);
}
};
}
/**
* @param attributes
*/
protected void updateAjaxAttributes(AjaxRequestAttributes attributes)
{
}
/**
*
* @see org.apache.wicket.markup.html.link.Link#onClick()
*/
@Override
public final void onClick()
{
onClick(null);
}
/**
* Callback for the onClick event. If ajax failed and this event was generated via a normal link
* the target argument will be null
*
* @param target
* ajax target if this linked was invoked using ajax, null otherwise
*/
@Override
public abstract void onClick(final AjaxRequestTarget target);
/**
* Removes any inline 'onclick' attributes set by Link#onComponentTag(ComponentTag).
*
* @param tag
* the component tag
*/
@Override
protected void onComponentTag(ComponentTag tag)
{
super.onComponentTag(tag);
// Ajax links work with JavaScript Event registration
tag.remove("onclick");
String tagName = tag.getName();
if (isEnabledInHierarchy() &&
!("a".equalsIgnoreCase(tagName) || "area".equalsIgnoreCase(tagName) || "link".equalsIgnoreCase(tagName)))
{
String msg = String.format(
"%s must be used only with <a>, <area> or <link> markup elements. "
+ "The fallback functionality doesn't work for other markup elements. "
+ "Component path: %s, markup element: <%s>.",
AjaxFallbackLink.class.getSimpleName(), getClassRelativePath(), tagName);
findMarkupStream().throwMarkupException(msg);
}
}
}