/*
* $Id: JsonExpressionEvaluator.java 20383 2010-11-29 19:44:13Z dfeist $
* --------------------------------------------------------------------------------------
* Copyright (c) MuleSoft, Inc. All rights reserved. http://www.mulesoft.com
*
* The software in this package is published under the terms of the CPAL v1.0
* license, a copy of which has been included with this distribution in the
* LICENSE.txt file.
*/
package org.mule.module.json;
import org.mule.api.MuleMessage;
import org.mule.api.MuleRuntimeException;
import org.mule.api.expression.ExpressionEvaluator;
import org.mule.config.i18n.CoreMessages;
import org.mule.util.NumberUtils;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.codehaus.jackson.JsonNode;
import org.codehaus.jackson.node.ArrayNode;
import org.codehaus.jackson.node.ObjectNode;
import org.codehaus.jackson.node.ValueNode;
/**
* An expression evaluator to allow users to define json expressions in their mule configuration, i.e.
* <code>
* #[json:person/addresses[0]/postcode]
* </code>
* <p/>
* See the {@link org.mule.module.json.JsonData} object for mor information about the query syntax.
* <p/>
* It is also possible to use this evaluator in {@link org.mule.routing.filters.ExpressionFilter} objects. For example
* a filter could be defined as -
* <p/>
* <code>
* #[json:person/registered]
* </code>
* <p/>
* Where 'registered' is a boolean value. It is also possible to filter on the existence of a value i.e.
* <p/>
* <code>
* #[json:person/favouriteColour]
* </code>
* <p/>
* Which would return true if 'favouriteColour' has been set. This evaluator also dds two logic operators you can use
* to create more sophisticated boolean expressions; equals and not equals -
* <p/>
* <code>
* #[json:person/favouriteColour = red]
* </code>
* <p/>
* or
* <p/>
* <code>
* #[json:person/favouriteColour != brown]
* </code>
*
* @see org.mule.module.json.JsonData
*/
public class JsonExpressionEvaluator implements ExpressionEvaluator
{
/**
* logger used by this class
*/
protected transient final Log logger = LogFactory.getLog(JsonExpressionEvaluator.class);
public Object evaluate(String expression, MuleMessage message)
{
String compareTo = null;
boolean not = false;
int start = expression.lastIndexOf("/");
if (start == -1)
{
start = 0;
}
int i=0;
if ((i = expression.indexOf("!=", start)) > -1)
{
compareTo = expression.substring(i + 2, expression.length()).trim();
expression = expression.substring(0, i).trim();
not = true;
}
else if ((i = expression.indexOf("=", start)) > -1)
{
compareTo = expression.substring(i + 1, expression.length()).trim();
expression = expression.substring(0, i).trim();
}
try
{
String json = message.getPayloadAsString();
JsonData data = new JsonData(json);
try
{
JsonNode resultNode = data.get(expression);
if (compareTo != null)
{
Object resultValue = resultNode.isValueNode() ? resultNode.getValueAsText() : resultNode;
if (compareTo.equalsIgnoreCase("null"))
{
boolean answer = resultValue == null;
return (not ? !answer : answer);
}
else if (resultValue instanceof Number && NumberUtils.isDigits(compareTo))
{
boolean answer = NumberUtils.createNumber(compareTo).equals(resultValue);
return (not ? !answer : answer);
}
else if (resultValue instanceof Boolean
&& (compareTo.equalsIgnoreCase("true") || compareTo.equalsIgnoreCase("false")))
{
boolean answer = resultValue.equals(Boolean.valueOf(compareTo));
return (not ? !answer : answer);
}
else
{
boolean answer = compareTo.equals(resultValue);
return (not ? !answer : answer);
}
}
else
{
return extractResultFromNode(resultNode);
}
}
catch (IllegalArgumentException e)
{
if (compareTo == null)
{
logger.debug("returning null for json expression: " + expression + ": " + e.getMessage());
return null;
}
//If the element does not exist but is matching against 'null' return true, otherwise false
return (compareTo.equalsIgnoreCase("null")) & !not;
}
}
catch (Exception e)
{
throw new MuleRuntimeException(CoreMessages.failedToProcessExtractorFunction(getName() + ":" + expression), e);
}
}
protected Object extractResultFromNode(JsonNode result)
{
if (result instanceof ValueNode)
{
return result.getValueAsText();
}
if (result instanceof ObjectNode)
{
return ((ObjectNode) result).toString();
}
else if (result instanceof ArrayNode)
{
List parts = new ArrayList();
for (Iterator<JsonNode> i = ((JsonNode) result).getElements(); i.hasNext();)
{
JsonNode arrayNode = i.next();
parts.add(extractResultFromNode(arrayNode));
}
return parts;
}
else
{
return result;
}
}
public void setName(String name)
{
throw new UnsupportedOperationException("setName");
}
public String getName()
{
return "json";
}
}