001/*
002 * Copyright 2002-2016 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016package org.springframework.web.reactive.result.view;
017
018import java.util.Map;
019
020import org.springframework.lang.Nullable;
021import org.springframework.web.server.ServerWebExchange;
022
023/**
024 * A contract for inspecting and potentially modifying request data values such
025 * as URL query parameters or form field values before they are rendered by a
026 * view or before a redirect.
027 *
028 * <p>Implementations may use this contract for example as part of a solution
029 * to provide data integrity, confidentiality, protection against cross-site
030 * request forgery (CSRF), and others or for other tasks such as automatically
031 * adding a hidden field to all forms and URLs.
032 *
033 * <p>View technologies that support this contract can obtain an instance to
034 * delegate to via {@link RequestContext#getRequestDataValueProcessor()}.
035 *
036 * @author Rossen Stoyanchev
037 * @since 5.0
038 */
039public interface RequestDataValueProcessor {
040
041        /**
042         * Invoked when a new form action is rendered.
043         * @param exchange the current exchange
044         * @param action the form action
045         * @param httpMethod the form HTTP method
046         * @return the action to use, possibly modified
047         */
048        String processAction(ServerWebExchange exchange, String action, String httpMethod);
049
050        /**
051         * Invoked when a form field value is rendered.
052         * @param exchange the current exchange
053         * @param name the form field name
054         * @param value the form field value
055         * @param type the form field type ("text", "hidden", etc.)
056         * @return the form field value to use, possibly modified
057         */
058        String processFormFieldValue(ServerWebExchange exchange, String name, String value, String type);
059
060        /**
061         * Invoked after all form fields have been rendered.
062         * @param exchange the current exchange
063         * @return additional hidden form fields to be added, or {@code null}
064         */
065        @Nullable
066        Map<String, String> getExtraHiddenFields(ServerWebExchange exchange);
067
068        /**
069         * Invoked when a URL is about to be rendered or redirected to.
070         * @param exchange the current exchange
071         * @param url the URL value
072         * @return the URL to use, possibly modified
073         */
074        String processUrl(ServerWebExchange exchange, String url);
075
076}