Merge pull request #438 from yasserzamani/WW-5087

WW-5087 handle Parameter.Empty properly

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

@@ -32,6 +32,7 @@ import com.opensymphony.xwork2.util.reflection.ReflectionContextState;
 import org.apache.logging.log4j.LogManager;
 import org.apache.logging.log4j.Logger;
 import org.apache.struts2.dispatcher.HttpParameters;
+import org.apache.struts2.dispatcher.Parameter;
 
 import java.util.Map;
 
@@ -173,7 +174,10 @@ public class AliasInterceptor extends AbstractInterceptor {
                         HttpParameters contextParameters = ActionContext.getContext().getParameters();
 
                         if (null != contextParameters) {
-                            value = new Evaluated(contextParameters.get(name));
+                            Parameter param = contextParameters.get(name);
+                            if (param.isDefined()) {
+                                value = new Evaluated(param.getValue());
+                            }
                         }
                     }
                     if (value.isDefined()) {

core/src/test/java/com/opensymphony/xwork2/interceptor/AliasInterceptorTest.java

@@ -23,6 +23,7 @@ import com.opensymphony.xwork2.config.entities.ActionConfig;
 import com.opensymphony.xwork2.config.providers.XmlConfigurationProvider;
 import com.opensymphony.xwork2.mock.MockActionInvocation;
 import com.opensymphony.xwork2.mock.MockActionProxy;
+import org.apache.struts2.dispatcher.HttpParameters;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -60,7 +61,30 @@ public class AliasInterceptorTest extends XWorkTestCase {
         actionOne.setFoo(17);
         actionOne.setBar(23);
         proxy.execute();
+        assertEquals("name to be copied", actionOne.getAliasSource());
         assertEquals(actionOne.getAliasSource(), actionOne.getAliasDest());
+        assertNull(actionOne.getBlah());    //  WW-5087
+    }
+
+    public void testNotExisting() throws Exception {
+        Map<String, Object> params = new HashMap<>();
+        Map<String, Object> httpParams = new HashMap<>();
+        httpParams.put("notExisting", "from http parameter");
+        params.put(ActionContext.PARAMETERS, HttpParameters.create(httpParams).build());
+
+        XmlConfigurationProvider provider = new XmlConfigurationProvider("xwork-sample.xml");
+        container.inject(provider);
+        loadConfigurationProviders(provider);
+        ActionProxy proxy = actionProxyFactory.createActionProxy("", "aliasTest", null, params);
+        SimpleAction actionOne = (SimpleAction) proxy.getAction();
+
+        // prevent ERROR result
+        actionOne.setFoo(-1);
+        actionOne.setBar(1);
+
+        proxy.execute();
+        assertEquals("from http parameter", actionOne.getBlah());
+        assertNull(actionOne.getAliasDest());    //  WW-5087
     }
 
     public void testInvalidAliasExpression() throws Exception {

core/src/test/resources/xwork-sample.xml

@@ -97,7 +97,7 @@
         </action>
 
         <action name="aliasTest" class="com.opensymphony.xwork2.SimpleAction">
-           	<param name="aliases">#{ "aliasSource" : "aliasDest", "bar":"baz" }</param>
+           	<param name="aliases">#{ "aliasSource" : "aliasDest", "bar":"baz", "notExisting":"blah" }</param>
 			<interceptor-ref name="params"/>
          	<interceptor-ref name="alias"/>
          	<result name="success" type="mock" />