EmptyStringToNullELResolver fixed for Tomcat

Signed-off-by: pizzi80 <[email protected]>
pizzi80 · Jun 22, 2023 · 7dba707 · 7dba707
1 parent 2fe3e42
commit 7dba707
Showing 1 changed file with 29 additions and 13 deletions.
diff --git a/impl/src/main/java/com/sun/faces/el/EmptyStringToNullELResolver.java b/impl/src/main/java/com/sun/faces/el/EmptyStringToNullELResolver.java
@@ -16,37 +16,53 @@
 
 package com.sun.faces.el;
 
-import java.beans.FeatureDescriptor;
-import java.util.Iterator;
-
 import jakarta.el.ELContext;
 import jakarta.el.ELResolver;
 
+import java.util.Map;
+import java.util.concurrent.ConcurrentHashMap;
+
 public class EmptyStringToNullELResolver extends ELResolver {
 
-    @Override
-    public Class<?> getCommonPropertyType(ELContext context, Object base) {
-        return String.class;
-    }
+    static final String EVALUATION_CONTEXT_CLASS_NAME = "EvaluationContext";
+
+    static final Map<Class<? extends ELContext>,Boolean> isEvaluationContext = new ConcurrentHashMap<>();
 
     @Override
-    @SuppressWarnings("unchecked")
     public <T> T convertToType(ELContext context, Object value, Class<T> targetType) {
-        if (value == null && targetType == String.class) {
+
+//        if ( String.class == targetType && context instanceof org.apache.el.lang.EvaluationContext ) // && context instanceof com.sun.faces.el.ELContextImpl
+//            System.out.println("value:["+value+"] - targetType:["+targetType+"]" + " {"+context+"}");
+
+        // NOTA: la soluzione proposta da BalusC ad oggi crea dei malfunzionamenti a JSF durante la valutazione di espressioni EL
+        //       ad esempio se faccio #{'hello'.concat(null)} darebbe errore perché null verrebbe trattato appunto come null e String.concat(null)
+        //       lancia un NullPointer, invece EL fa una conversione null -> '' e ti salva la vita
+
+        // Invece per ottenere il comportamento desiderato in fase di input
+        // sembra che EL-context in questione sia EvaluationContext
+
+        if (    value == null &&
+                String.class.equals(targetType) &&
+                isEvaluationContext.computeIfAbsent( context.getClass() , clazz -> clazz.getName().endsWith(EVALUATION_CONTEXT_CLASS_NAME) )
+        ) {
             context.setPropertyResolved(true);
+            return (T) null;
         }
-
+        //try {
         return (T) value;
+        //} catch (ClassCastException e) {
+        //    return null;
+        //}
     }
 
     @Override
-    public Iterator<FeatureDescriptor> getFeatureDescriptors(ELContext context, Object base) {
-        return null;
+    public Class<?> getCommonPropertyType(ELContext context, Object base) {
+        return String.class;
     }
 
     @Override
     public Class<?> getType(ELContext context, Object base, Object property) {
-        return null;
+        return String.class;
     }
 
     @Override