core/src/main/java/com/opensymphony/xwork2/interceptor/ConversionErrorInterceptor.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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.interceptor;

import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionInvocation;
import com.opensymphony.xwork2.conversion.impl.ConversionData;
import com.opensymphony.xwork2.conversion.impl.XWorkConverter;
import com.opensymphony.xwork2.util.ValueStack;
import org.apache.commons.text.StringEscapeUtils;

import java.util.HashMap;
import java.util.Map;


/**
 * <!-- START SNIPPET: description -->
 * ConversionErrorInterceptor adds conversion errors from the ActionContext to the Action's field errors.
 *
 * <p>
 * This interceptor adds any error found in the {@link ActionContext}'s conversionErrors map as a field error (provided
 * that the action implements {@link ValidationAware}). In addition, any field that contains a validation error has its
 * original value saved such that any subsequent requests for that value return the original value rather than the value
 * in the action. This is important because if the value "abc" is submitted and can't be converted to an int, we want to
 * display the original string ("abc") again rather than the int value (likely 0, which would make very little sense to
 * the user).
 * </p>
 * 
 * <p>
 * <b>Note:</b> Since 2.5.2, this interceptor extends {@link MethodFilterInterceptor}, therefore being
 * able to deal with excludeMethods / includeMethods parameters. See [Workflow Interceptor]
 * (class {@link DefaultWorkflowInterceptor}) for documentation and examples on how to use this feature.
 * </p>
 * 
 * <!-- END SNIPPET: description -->
 *
 * <p><u>Interceptor parameters:</u></p>
 *
 * <!-- START SNIPPET: parameters -->
 *
 * <ul>
 *  <li>None</li>
 * </ul>
 *
 * <!-- END SNIPPET: parameters -->
 *
 * <p> <u>Extending the interceptor:</u></p>
 *
 * <!-- START SNIPPET: extending -->
 *
 * Because this interceptor is not web-specific, it abstracts the logic for whether an error should be added. This
 * allows for web-specific interceptors to use more complex logic in the {@link #shouldAddError} method for when a value
 * has a conversion error but is null or empty or otherwise indicates that the value was never actually entered by the
 * user.
 *
 * <!-- END SNIPPET: extending -->
 *
 * <p> <u>Example code:</u></p>
 *
 * <pre>
 * <!-- START SNIPPET: example -->
 * &lt;action name="someAction" class="com.examples.SomeAction"&gt;
 *     &lt;interceptor-ref name="params"/&gt;
 *     &lt;interceptor-ref name="conversionError"/&gt;
 *     &lt;result name="success"&gt;good_result.ftl&lt;/result&gt;
 * &lt;/action&gt;
 * <!-- END SNIPPET: example -->
 * </pre>
 *
 * @author Jason Carreira
 */
public class ConversionErrorInterceptor extends MethodFilterInterceptor {

    public static final String ORIGINAL_PROPERTY_OVERRIDE = "original.property.override";

    protected Object getOverrideExpr(ActionInvocation invocation, Object value) {
        return escape(value);
    }

    protected String escape(Object value) {
        return "\"" + StringEscapeUtils.escapeJava(String.valueOf(value)) + "\"";
    }

    @Override
    public String doIntercept(ActionInvocation invocation) throws Exception {

        ActionContext invocationContext = invocation.getInvocationContext();
        Map<String, ConversionData> conversionErrors = invocationContext.getConversionErrors();
        ValueStack stack = invocationContext.getValueStack();

        HashMap<Object, Object> fakie = null;

        for (Map.Entry<String, ConversionData> entry : conversionErrors.entrySet()) {
            String propertyName = entry.getKey();
            ConversionData conversionData = entry.getValue();

            if (shouldAddError(propertyName, conversionData.getValue())) {
                String message = XWorkConverter.getConversionErrorMessage(propertyName, conversionData.getToClass(), stack);

                Object action = invocation.getAction();
                if (action instanceof ValidationAware) {
                    ValidationAware va = (ValidationAware) action;
                    va.addFieldError(propertyName, message);
                }

                if (fakie == null) {
                    fakie = new HashMap<>();
                }

                fakie.put(propertyName, getOverrideExpr(invocation, conversionData.getValue()));
            }
        }

        if (fakie != null) {
            // if there were some errors, put the original (fake) values in place right before the result
            stack.getContext().put(ORIGINAL_PROPERTY_OVERRIDE, fakie);
            invocation.addPreResultListener(new PreResultListener() {
                public void beforeResult(ActionInvocation invocation, String resultCode) {
                    Map<Object, Object> fakie = (Map<Object, Object>) invocation.getInvocationContext().get(ORIGINAL_PROPERTY_OVERRIDE);

                    if (fakie != null) {
                        invocation.getStack().setExprOverrides(fakie);
                    }
                }
            });
        }
        return invocation.invoke();
    }

    protected boolean shouldAddError(String propertyName, Object value) {
        return true;
    }
}