WW-5585: Implement dynamic parameter evaluation for file upload validation

apps/showcase/src/main/java/org/apache/struts2/showcase/fileupload/DynamicFileUploadAction.java

@@ -0,0 +1,225 @@
+/*
+ * 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 org.apache.struts2.showcase.fileupload;
+
+import org.apache.logging.log4j.LogManager;
+import org.apache.logging.log4j.Logger;
+import org.apache.struts2.ActionSupport;
+import org.apache.struts2.Preparable;
+import org.apache.struts2.ServletActionContext;
+import org.apache.struts2.action.UploadedFilesAware;
+import org.apache.struts2.dispatcher.multipart.UploadedFile;
+import org.apache.struts2.interceptor.parameter.StrutsParameter;
+
+import java.util.List;
+
+/**
+ * <p>
+ * Demonstrates dynamic file upload validation using WithLazyParams.
+ * This action shows how file upload validation rules can be determined
+ * at runtime based on action properties, session data, or other dynamic values.
+ * </p>
+ *
+ * <p>
+ * The validation parameters (allowedTypes, allowedExtensions, maximumSize)
+ * are set dynamically in the prepare() method and then referenced in struts.xml
+ * using ${...} expressions. This allows the same action to enforce different
+ * validation rules based on runtime conditions.
+ * </p>
+ *
+ * <p>
+ * This example demonstrates two use cases:
+ * </p>
+ * <ul>
+ * <li><strong>Document Upload:</strong> Accepts PDF and Word documents up to 5MB</li>
+ * <li><strong>Image Upload:</strong> Accepts JPEG and PNG images up to 2MB</li>
+ * </ul>
+ *
+ * @see org.apache.struts2.interceptor.WithLazyParams
+ * @see org.apache.struts2.interceptor.ActionFileUploadInterceptor
+ */
+public class DynamicFileUploadAction extends ActionSupport implements Preparable, UploadedFilesAware {
+
+    private static final Logger LOG = LogManager.getLogger(DynamicFileUploadAction.class);
+
+    private UploadedFile uploadedFile;
+    private String contentType;
+    private String fileName;
+    private String originalName;
+    private String inputName;
+    private String uploadType = "document";
+
+    private transient UploadConfig uploadConfig;
+
+    @Override
+    public String input() {
+        return INPUT;
+    }
+
+    public String upload() {
+        if (uploadedFile == null) {
+            addActionError("Please select a file to upload");
+            return INPUT;
+        }
+
+        return SUCCESS;
+    }
+
+    @Override
+    public void withUploadedFiles(List<UploadedFile> uploadedFiles) {
+        if (!uploadedFiles.isEmpty()) {
+            LOG.info("Uploaded file: {}", uploadedFiles.get(0));
+            this.uploadedFile = uploadedFiles.get(0);
+            this.fileName = uploadedFile.getName();
+            this.contentType = uploadedFile.getContentType();
+            this.originalName = uploadedFile.getOriginalName();
+            this.inputName = uploadedFile.getInputName();
+        }
+    }
+
+    // Getters and Setters
+
+    public String getContentType() {
+        return contentType;
+    }
+
+    public String getFileName() {
+        return fileName;
+    }
+
+    public String getOriginalName() {
+        return originalName;
+    }
+
+    public String getInputName() {
+        return inputName;
+    }
+
+    public Object getUploadedFile() {
+        return uploadedFile != null ? uploadedFile.getContent() : null;
+    }
+
+    public long getUploadSize() {
+        return uploadedFile != null ? uploadedFile.length() : 0;
+    }
+
+    public String getUploadType() {
+        return uploadType;
+    }
+
+    @StrutsParameter
+    public void setUploadType(String uploadType) {
+        this.uploadType = uploadType;
+    }
+
+    @Override
+    public void prepare() throws Exception {
+        // no-op
+    }
+
+    public void prepareUpload() {
+        String type = ServletActionContext.getRequest().getParameter("uploadType");
+        prepareUploadConfig(type != null ? type : "document");
+    }
+
+    private void prepareUploadConfig(String uploadType) {
+        uploadConfig = new UploadConfig();
+        LOG.debug("Configure validation rules based on upload type: {}", uploadType);
+        if ("image".equals(uploadType)) {
+            // Image upload configuration
+            uploadConfig.setAllowedMimeTypes("image/jpeg,image/png");
+            uploadConfig.setAllowedExtensions(".jpg,.jpeg,.png");
+            uploadConfig.setMaxFileSize(2097152L); // 2MB
+            uploadConfig.setDescription("images (JPEG, PNG)");
+        } else {
+            // Document upload configuration (default)
+            uploadConfig.setAllowedMimeTypes("application/pdf,application/msword,application/vnd.openxmlformats-officedocument.wordprocessingml.document");
+            uploadConfig.setAllowedExtensions(".pdf,.doc,.docx");
+            uploadConfig.setMaxFileSize(5242880L); // 5MB
+            uploadConfig.setDescription("documents (PDF, Word)");
+        }
+    }
+
+    /**
+     * Returns the upload configuration object.
+     * This is used in struts.xml with ${uploadConfig.allowedMimeTypes} expressions.
+     */
+    public UploadConfig getUploadConfig() {
+        return uploadConfig;
+    }
+
+    /**
+     * Configuration holder for dynamic file upload validation rules.
+     */
+    public static class UploadConfig {
+        private String allowedMimeTypes;
+        private String allowedExtensions;
+        private Long maxFileSize;
+        private String description;
+
+        public String getAllowedMimeTypes() {
+            return allowedMimeTypes;
+        }
+
+        public void setAllowedMimeTypes(String allowedMimeTypes) {
+            this.allowedMimeTypes = allowedMimeTypes;
+        }
+
+        public String getAllowedExtensions() {
+            return allowedExtensions;
+        }
+
+        public void setAllowedExtensions(String allowedExtensions) {
+            this.allowedExtensions = allowedExtensions;
+        }
+
+        public Long getMaxFileSize() {
+            return maxFileSize;
+        }
+
+        public void setMaxFileSize(Long maxFileSize) {
+            this.maxFileSize = maxFileSize;
+        }
+
+        public String getDescription() {
+            return description;
+        }
+
+        public void setDescription(String description) {
+            this.description = description;
+        }
+
+        /**
+         * Returns a human-readable string representation of the max file size.
+         */
+        public String getMaxFileSizeFormatted() {
+            if (maxFileSize == null) {
+                return "unlimited";
+            }
+
+            if (maxFileSize < 1024) {
+                return maxFileSize + " bytes";
+            } else if (maxFileSize < 1024 * 1024) {
+                return (maxFileSize / 1024) + " KB";
+            } else {
+                return (maxFileSize / (1024 * 1024)) + " MB";
+            }
+        }
+    }
+}

apps/showcase/src/main/resources/log4j2.xml

@@ -30,5 +30,8 @@
             <AppenderRef ref="STDOUT"/>
         </Root>
         <Logger name="org.apache.struts2" level="info"/>
+        <Logger name="org.apache.struts2.showcase.fileupload" level="debug"/>
+        <Logger name="org.apache.struts2.inject" level="debug"/>
+        <Logger name="org.apache.struts2.interceptor.ActionFileUploadInterceptor" level="debug"/>
     </Loggers>
 </Configuration>

apps/showcase/src/main/resources/struts-fileupload.xml

@@ -20,43 +20,66 @@
  */
 -->
 <!DOCTYPE struts PUBLIC
-	"-//Apache Software Foundation//DTD Struts Configuration 6.0//EN"
-	"https://struts.apache.org/dtds/struts-6.0.dtd">
+        "-//Apache Software Foundation//DTD Struts Configuration 6.0//EN"
+        "https://struts.apache.org/dtds/struts-6.0.dtd">
 
 <struts>
 
-	<constant name="struts.multipart.maxSize" value="10240" />
+    <constant name="struts.multipart.maxSize" value="10240"/>
 
-	<package name="fileupload" extends="struts-default" namespace="/fileupload">
+    <package name="fileupload" extends="struts-default" namespace="/fileupload">
 
         <action name="upload" class="org.apache.struts2.showcase.fileupload.FileUploadAction" method="input">
-			<result>/WEB-INF/fileupload/upload.jsp</result>
-		</action>
+            <result>/WEB-INF/fileupload/upload.jsp</result>
+        </action>
 
         <action name="doUpload" class="org.apache.struts2.showcase.fileupload.FileUploadAction" method="upload">
-        	<result name="input">/WEB-INF/fileupload/upload.jsp</result>
-			<result>/WEB-INF/fileupload/upload-success.jsp</result>
-		</action>
+            <result name="input">/WEB-INF/fileupload/upload.jsp</result>
+            <result>/WEB-INF/fileupload/upload-success.jsp</result>
+        </action>
 
-		<action name="multipleUploadUsingList">
-			<result>/WEB-INF/fileupload/multipleUploadUsingList.jsp</result>
-		</action>
+        <action name="multipleUploadUsingList">
+            <result>/WEB-INF/fileupload/multipleUploadUsingList.jsp</result>
+        </action>
 
-		<action name="doMultipleUploadUsingList" class="org.apache.struts2.showcase.fileupload.MultipleFileUploadUsingListAction" method="upload">
-			<result name="input">/WEB-INF/fileupload/multipleUploadUsingList.jsp</result>
-			<result>/WEB-INF/fileupload/multiple-success.jsp</result>
-		</action>
+        <action name="doMultipleUploadUsingList"
+                class="org.apache.struts2.showcase.fileupload.MultipleFileUploadUsingListAction" method="upload">
+            <result name="input">/WEB-INF/fileupload/multipleUploadUsingList.jsp</result>
+            <result>/WEB-INF/fileupload/multiple-success.jsp</result>
+        </action>
 
 
-		<action name="multipleUploadUsingArray">
-			<result>/WEB-INF/fileupload/multipleUploadUsingArray.jsp</result>
-		</action>
+        <action name="multipleUploadUsingArray">
+            <result>/WEB-INF/fileupload/multipleUploadUsingArray.jsp</result>
+        </action>
 
-		<action name="doMultipleUploadUsingArray" class="org.apache.struts2.showcase.fileupload.MultipleFileUploadUsingArrayAction" method="upload">
-			<result name="input">/WEB-INF/fileupload/multipleUploadUsingArray.jsp</result>
-			<result>/WEB-INF/fileupload/multiple-success.jsp</result>
-		</action>
+        <action name="doMultipleUploadUsingArray"
+                class="org.apache.struts2.showcase.fileupload.MultipleFileUploadUsingArrayAction" method="upload">
+            <result name="input">/WEB-INF/fileupload/multipleUploadUsingArray.jsp</result>
+            <result>/WEB-INF/fileupload/multiple-success.jsp</result>
+        </action>
 
+        <!-- Dynamic File Upload with WithLazyParams -->
+        <action name="dynamicUpload" class="org.apache.struts2.showcase.fileupload.DynamicFileUploadAction"
+                method="input">
+            <result name="input">/WEB-INF/fileupload/dynamic-upload.jsp</result>
+        </action>
+
+        <action name="doDynamicUpload" class="org.apache.struts2.showcase.fileupload.DynamicFileUploadAction"
+                method="upload">
+            <!-- 
+                WithLazyParams allows dynamic parameter evaluation.
+                The ${...} expressions are evaluated at runtime from the ValueStack,
+                allowing validation rules to be determined by action state.
+            -->
+            <interceptor-ref name="defaultStack">
+                <param name="actionFileUpload.allowedTypes">${uploadConfig.allowedMimeTypes}</param>
+                <param name="actionFileUpload.allowedExtensions">${uploadConfig.allowedExtensions}</param>
+                <param name="actionFileUpload.maximumSize">${uploadConfig.maxFileSize}</param>
+            </interceptor-ref>
+            <result name="input">/WEB-INF/fileupload/dynamic-upload.jsp</result>
+            <result>/WEB-INF/fileupload/dynamic-upload-success.jsp</result>
+        </action>
 
     </package>
 </struts>

apps/showcase/src/main/resources/struts.xml

@@ -36,14 +36,7 @@
 
     <constant name="struts.allowlist.enable" value="true" />
     <constant name="struts.parameters.requireAnnotations" value="true" />
-    <constant name="struts.allowlist.packageNames" value="
-            org.apache.struts2.showcase.model,
-            org.apache.struts2.showcase.modelDriven.model
-    "/>
-    <constant name="struts.allowlist.classes" value="
-            org.apache.struts2.showcase.hangman.Hangman,
-            org.apache.struts2.showcase.hangman.Vocab
-    "/>
+    <constant name="struts.allowlist.packageNames" value="org.apache.struts2.showcase"/>
 
     <constant name="struts.convention.package.locators.basePackage" value="org.apache.struts2.showcase" />
     <constant name="struts.convention.result.path" value="/WEB-INF" />

apps/showcase/src/main/webapp/WEB-INF/decorators/main.jsp

@@ -192,6 +192,10 @@
                                 <s:url var="url" action="upload" namespace="/fileupload"/>
                                 <s:a href="%{#url}">Single File Upload</s:a>
                             </li>
+                            <li>
+                                <s:url var="url" action="dynamicUpload" namespace="/fileupload"/>
+                                <s:a href="%{#url}">Single File Upload - dynamic config</s:a>
+                            </li>
                             <li>
                                 <s:url var="url" action="multipleUploadUsingList" namespace="/fileupload"/>
                                 <s:a href="%{#url}">Multiple File Upload (List)</s:a>