JavaScriptExpressionSendingAjaxBehavior.java

/**
 *   Copyright 2012-2013 Wicked Charts (http://wicked-charts.googlecode.com)
 *
 *   Licensed 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 com.googlecode.wickedcharts.wicket6;

import java.util.HashMap;
import java.util.Map;

import org.apache.wicket.ajax.AbstractDefaultAjaxBehavior;
import org.apache.wicket.ajax.attributes.AjaxRequestAttributes;
import org.apache.wicket.request.cycle.RequestCycle;
import org.apache.wicket.request.http.WebRequest;
import org.apache.wicket.util.string.StringValue;

/**
 * This AJAX behavior passes the values of a set of defined javascript variables
 * to the server via AJAX.
 * 
 * @author Tom Hombergs (tom.hombergs@gmail.com)
 * 
 */
public abstract class JavaScriptExpressionSendingAjaxBehavior extends AbstractDefaultAjaxBehavior {

	private final Map<String, String> javascriptExpressions = new HashMap<String, String>();

	/**
	 * Reads the value of the given javascript variable from the AJAX request.
	 * 
	 * @param parameterName
	 *          the parameter name of the javascript expression whose value to
	 *          read. The parameterName must have been specified earlier when
	 *          calling {@link #addJavaScriptValue(String, String)}.
	 * @return the string representation of the javascript expression's value
	 */
	protected StringValue getVariableValue(String parameterName) {
		RequestCycle cycle = RequestCycle.get();
		WebRequest webRequest = (WebRequest) cycle.getRequest();
		StringValue value = webRequest.getQueryParameters().getParameterValue(parameterName);
		return value;
	}

	@Override
	public CharSequence getCallbackScript() {
		String script = super.getCallbackScript().toString();
		for (String parameterName : this.javascriptExpressions.keySet()) {
			String expression = this.javascriptExpressions.get(parameterName);
			script = script.replace("\"" + expression + "\"", expression);
		}
		return script;
	}

	/**
	 * Adds a javascript expression whose value to be passed from client to
	 * server. The result value of this expression is sent to the server via AJAX
	 * and can be accessed using the method {@link #getVariableValue(String)}. A
	 * javascript variable with the given name must exist within the scope the
	 * callback script of this behavior is called on the client side!
	 * 
	 * @param parameterName
	 *          the name under which the value of the given javascript expression
	 *          can be accessed later
	 * @param javascriptExpression
	 *          the javascript expression whose value pass from client to server.
	 */
	public void addJavaScriptValue(String parameterName, String javascriptExpression) {
		this.javascriptExpressions.put(parameterName, javascriptExpression);
	}

	/**
	 * Adds a set of javascript expressions to be passed from client to server.
	 * 
	 * @param parameterMap
	 *          a map containing the name of a parameter as key and a javascript
	 *          expression as value
	 * 
	 * @see #addJavaScriptValue(String, String)
	 */
	public void addJavaScriptValues(Map<String, String> parameterMap) {
		for (String parameterName : parameterMap.keySet()) {
			this.javascriptExpressions.put(parameterName, parameterMap.get(parameterName));
		}
	}

	@Override
	protected void updateAjaxAttributes(AjaxRequestAttributes attributes) {
		super.updateAjaxAttributes(attributes);
		for (String parameterName : this.javascriptExpressions.keySet()) {
			attributes.getExtraParameters().put(parameterName, this.javascriptExpressions.get(parameterName));
		}
	}

}