Struts example source code file (VisitorFieldValidator.java)

This example Struts source code file (VisitorFieldValidator.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Struts tags/keywords

appendingvalidatorcontext, appendingvalidatorcontext, collection, collection, delegatingvalidatorcontext, object, object, override, string, string, util, validationexception, validatorcontext, valuestack, visitorvalidator

The Struts VisitorFieldValidator.java source code

/*
 * 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.ActionContext;
import com.opensymphony.xwork2.inject.Inject;
import com.opensymphony.xwork2.util.ValueStack;
import com.opensymphony.xwork2.validator.ActionValidatorManager;
import com.opensymphony.xwork2.validator.DelegatingValidatorContext;
import com.opensymphony.xwork2.validator.ValidationException;
import com.opensymphony.xwork2.validator.ValidatorContext;

import java.util.Collection;


/**
 * <!-- START SNIPPET: javadoc -->
 * The VisitorFieldValidator allows you to forward validation to object
 * properties of your action using the object's own validation files.  This
 * allows you to use the ModelDriven development pattern and manage your
 * validations for your models in one place, where they belong, next to your
 * model classes.  The VisitorFieldValidator can handle either simple Object
 * properties, Collections of Objects, or Arrays.
 * <!-- END SNIPPET: javadoc -->
 * <p/>
 *
 * <!-- START SNIPPET: parameters -->
 * <ul>
 * <li>fieldName - field name if plain-validator syntax is used, not needed if field-validator syntax is used
 * <li>context - the context of which validation should take place. Optional
 * <li>appendPrefix - the prefix to be added to field. Optional 
 * </ul>
 * <!-- END SNIPPET: parameters -->
 *
 * <pre>
 * <!-- START SNIPPET: example -->
 *    <validators>
 *        <!-- Plain Validator Syntax -->
 *        <validator type="visitor">
 *            <param name="fieldName">user</param>
 *            <param name="context">myContext</param>
 *            <param name="appendPrefix">true</param>
 *        </validator>
 *
 *        <!-- Field Validator Syntax -->
 *        <field name="user">
 *           <field-validator type="visitor">
 *              <param name="context">myContext</param>
 *              <param name="appendPrefix">true</param>
 *           </field-validator>
 *        </field>
 *    </validators>
 * <!-- END SNIPPET: example -->
 * </pre>
 *
 * <!-- START SNIPPET: explanation -->
 * <p>In the example above, if the acion's getUser() method return User object, XWork
 * will look for User-myContext-validation.xml for the validators. Since appednPrefix is true,
 * every field name will be prefixed with 'user' such that if the actual field name for 'name' is
 * 'user.name' </p>
 * <!-- END SNIPPET: explanation -->
 *
 * @author Jason Carreira
 * @author Rainer Hermanns
 * @version $Date: 2009-12-27 19:18:29 +0100 (Sun, 27 Dec 2009) $ $Id: VisitorFieldValidator.java 894090 2009-12-27 18:18:29Z martinc $
 */
public class VisitorFieldValidator extends FieldValidatorSupport {

    private String context;
    private boolean appendPrefix = true;
    private ActionValidatorManager actionValidatorManager;


    @Inject
    public void setActionValidatorManager(ActionValidatorManager mgr) {
        this.actionValidatorManager = mgr;
    }

    /**
     * Sets whether the field name of this field validator should be prepended to the field name of
     * the visited field to determine the full field name when an error occurs.  The default is
     * true.
     */
    public void setAppendPrefix(boolean appendPrefix) {
        this.appendPrefix = appendPrefix;
    }

    /**
     * Flags whether the field name of this field validator should be prepended to the field name of
     * the visited field to determine the full field name when an error occurs.  The default is
     * true.
     */
    public boolean isAppendPrefix() {
        return appendPrefix;
    }

    public void setContext(String context) {
        this.context = context;
    }

    public String getContext() {
        return context;
    }

    public void validate(Object object) throws ValidationException {
        String fieldName = getFieldName();
        Object value = this.getFieldValue(fieldName, object);
        if (value == null) {
            log.warn("The visited object is null, VisitorValidator will not be able to handle validation properly. Please make sure the visited object is not null for VisitorValidator to function properly");
            return;
        }
        ValueStack stack = ActionContext.getContext().getValueStack();

        stack.push(object);

        String visitorContext = (context == null) ? ActionContext.getContext().getName() : context;

        if (value instanceof Collection) {
            Collection coll = (Collection) value;
            Object[] array = coll.toArray();

            validateArrayElements(array, fieldName, visitorContext);
        } else if (value instanceof Object[]) {
            Object[] array = (Object[]) value;

            validateArrayElements(array, fieldName, visitorContext);
        } else {
            validateObject(fieldName, value, visitorContext);
        }

        stack.pop();
    }

    private void validateArrayElements(Object[] array, String fieldName, String visitorContext) throws ValidationException {
        if (array == null) {
            return;
        }

        for (int i = 0; i < array.length; i++) {
            Object o = array[i];
            if (o != null) {
                validateObject(fieldName + "[" + i + "]", o, visitorContext);
            }
        }
    }

    private void validateObject(String fieldName, Object o, String visitorContext) throws ValidationException {
        ValueStack stack = ActionContext.getContext().getValueStack();
        stack.push(o);

        ValidatorContext validatorContext;

        if (appendPrefix) {
            validatorContext = new AppendingValidatorContext(getValidatorContext(), o, fieldName, getMessage(o));
        } else {
            ValidatorContext parent = getValidatorContext();
            validatorContext = new DelegatingValidatorContext(parent, DelegatingValidatorContext.makeTextProvider(o, parent), parent);
        }

        actionValidatorManager.validate(o, visitorContext, validatorContext);
        stack.pop();
    }


    public static class AppendingValidatorContext extends DelegatingValidatorContext {
        private String field;
        private String message;
        private ValidatorContext parent;

        public AppendingValidatorContext(ValidatorContext parent, Object object, String field, String message) {
            super(parent, makeTextProvider(object, parent), parent);

            this.field = field;
            this.message = message;
            this.parent = parent;
        }

        /**
         * Translates a simple field name into a full field name in Ognl syntax
         *
         * @param fieldName field name in OGNL syntax
         * @return field name in OGNL syntax
         */
        @Override
        public String getFullFieldName(String fieldName) {
            return field + "." + fieldName;
        }

        public String getFullFieldNameFromParent(String fieldName) {
            return parent.getFullFieldName(field + "." + fieldName);
        }

        @Override
        public void addActionError(String anErrorMessage) {
            super.addFieldError(getFullFieldName(field), message + anErrorMessage);
        }

        @Override
        public void addFieldError(String fieldName, String errorMessage) {
            super.addFieldError(getFullFieldName(fieldName), message + errorMessage);
        }
    }
}