/*
 * 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;

import java.lang.reflect.Array;
import java.util.Collection;


/**
 * <!-- START SNIPPET: javadoc -->
 * RequiredFieldValidator checks if the specified field is not null.
 * <!-- END SNIPPET: javadoc -->
 *
 * <!-- START SNIPPET: parameters -->
 * <ul>
 * 		<li>fieldName - field name if plain-validator syntax is used, not needed if field-validator syntax is used</li>
 * </ul>
 * <!-- END SNIPPET: parameters -->
 *
 * <pre>
 * <!-- START SNIPPET: example -->
 * 	   <validators>
 * 
 *         <!-- Plain Validator Syntax -->
 *         <validator type="required">
 *             <param name="fieldName">username</param>
 *             <message>username must not be null</message>
 *         </validator>
 * 
 * 
 *         <!-- Field Validator Syntax -->
 *         <field name="username">
 *             <field-validator type="required">
 *             	   <message>username must not be null</message>
 *             </field-validator>
 *         </field>
 * 
 *     </validators>
 * <!-- END SNIPPET: example -->
 * </pre>
 * 
 * 
 *
 * @author rainerh
 */
public class RequiredFieldValidator extends FieldValidatorSupport {

    public void validate(Object object) throws ValidationException {
        String fieldName = getFieldName();
        Object value = this.getFieldValue(fieldName, object);

        if (value == null) {
            addFieldError(fieldName, object);
        } else if (value.getClass().isArray() && Array.getLength(value) == 0) {
            addFieldError(fieldName, object);
        } else if (Collection.class.isAssignableFrom(value.getClass()) && ((Collection) value).size() == 0) {
            addFieldError(fieldName, object);
        }
    }
}