/*
 * Copyright 2002-2006,2009 The Apache Software Foundation.
 * 
 * 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.opensymphony.xwork2.validator.validators;

import com.opensymphony.xwork2.validator.ValidationException;


/**
 * <!-- START SNIPPET: javadoc -->
 * Validates a field using an OGNL expression.
 * <!-- END SNIPPET: javadoc -->
 * <p/>
 * 
 * <!-- START SNIPPET: parameters -->
 * <ul>
 *    <li>fieldName - The field name this validator is validating. Required if using Plain-Validator Syntax otherwise not required</li>
 *    <li>expression - The Ognl expression (must evaluate to a boolean) which is to be evalidated the stack</li>
 * </ul>
 * <!-- END SNIPPET: parameters -->
 * 
 * <pre>
 * <!-- START SNIPPET: example -->
 *    <!-- Plain Validator Syntax -->
 *    <validators>
 *        <!-- Plain Validator Syntax -->
 *        <validator type="fieldexpression">
 *           <param name="fieldName">myField</param>
 *           <param name="expression"><![CDATA[#myCreditLimit > #myGirfriendCreditLimit]]></param>
 *           <message>My credit limit should be MORE than my girlfriend</message>
 *        <validator>
 *        
 *        <!-- Field Validator Syntax -->
 *        <field name="myField">
 *            <field-validator type="fieldexpression">
 *                <param name="expression"><![CDATA[#myCreditLimit > #myGirfriendCreditLimit]]></param>
 *                <message>My credit limit should be MORE than my girlfriend</message>
 *            </field-validator>
 *        </field>
 *        
 *    </vaidators>
 * <!-- END SNIPPET: example -->
 * </pre>
 * 
 *
 * @author $Author$
 * @version $Revision$
 */
public class FieldExpressionValidator extends FieldValidatorSupport {

    private String expression;

    public void setExpression(String expression) {
        this.expression = expression;
    }

    public String getExpression() {
        return expression;
    }

    public void validate(Object object) throws ValidationException {
        String fieldName = getFieldName();

        Boolean answer = Boolean.FALSE;
        Object obj = null;

        try {
            obj = getFieldValue(expression, object);
        } catch (ValidationException e) {
            throw e;
        } catch (Exception e) {
            // let this pass, but it will be logged right below
        }

        if ((obj != null) && (obj instanceof Boolean)) {
            answer = (Boolean) obj;
        } else {
            log.warn("Got result of " + obj + " when trying to get Boolean.");
        }

        if (!answer.booleanValue()) {
            addFieldError(fieldName, object);
        }
    }
}