Fix #4009 (#4015): Locale coercion to Locale.ROOT

FasterXML · Jul 7, 2023 · e16a84b · e16a84b
1 parent 9684204
commit e16a84b
Show file tree

Hide file tree

Showing 5 changed files with 24 additions and 11 deletions.
diff --git a/release-notes/CREDITS-2.x b/release-notes/CREDITS-2.x
@@ -1654,5 +1654,10 @@ David Schlosnagle (schlosna@github)
  * Contributed #4008: Optimize `ObjectNode` findValue(s) and findParent(s) fast paths
   (2.16.0)
 
+Philipp Kräutli (pkraeutli@github)
+ * Reportedd #4009: Locale "" is deserialised as `null` if `ACCEPT_EMPTY_STRING_AS_NULL_OBJECT`
+   is enabled
+  (2.16.0)
+
 
 
diff --git a/release-notes/VERSION-2.x b/release-notes/VERSION-2.x
@@ -27,6 +27,9 @@ Project: jackson-databind
   on serialization
 #4008: Optimize `ObjectNode` findValue(s) and findParent(s) fast paths
  (contributed by David S)
+#4009: Locale "" is deserialised as `null` if `ACCEPT_EMPTY_STRING_AS_NULL_OBJECT`
+  is enabled
+ (reported by Philipp K)
 #4011: Add guardrail setting for `TypeParser` handling of type parameters
 
 2.15.3 (not yet released)

diff --git a/src/main/java/com/fasterxml/jackson/databind/DeserializationFeature.java b/src/main/java/com/fasterxml/jackson/databind/DeserializationFeature.java
@@ -354,13 +354,11 @@ public enum DeserializationFeature implements ConfigFeature
      * kinds of JSON values); if enabled, empty JSON String can be taken
      * to be equivalent of JSON null.
      *<p>
-     * NOTE: this does NOT apply to scalar values such as booleans and numbers;
-     * whether they can be coerced depends on
+     * NOTE: this does NOT apply to scalar values such as booleans, numbers
+     * and date/time types;
+     * whether these can be coerced depends on
      * {@link MapperFeature#ALLOW_COERCION_OF_SCALARS}.
      *<p>
-     * IMPORTANT: This feature might work even when an empty string {@code ""}
-     * may be a valid value for some types.
-     *<p>
      * Feature is disabled by default.
      */
     ACCEPT_EMPTY_STRING_AS_NULL_OBJECT(false),

diff --git a/src/main/java/com/fasterxml/jackson/databind/cfg/CoercionConfigs.java b/src/main/java/com/fasterxml/jackson/databind/cfg/CoercionConfigs.java
@@ -229,18 +229,20 @@ public CoercionAction findCoercion(DeserializationConfig config,
         }
 
         if (inputShape == CoercionInputShape.EmptyString) {
+            // 09-Jun-2020, tatu: Seems necessary to support backwards-compatibility with
+            //     2.11, wrt "FromStringDeserializer" supported types
+            // 06-Jul-2023, tatu: For 2.16, moved before the other check to prevent coercion
+            //     to null where conversion allowed/expected
+            if (targetType == LogicalType.OtherScalar) {
+                return CoercionAction.TryConvert;
+            }
             // Since coercion of scalar must be enabled (see check above), allow empty-string
             // coercions by default even without this setting
             if (baseScalar
                     // Default for setting is false
                     || config.isEnabled(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT)) {
                 return CoercionAction.AsNull;
             }
-            // 09-Jun-2020, tatu: Seems necessary to support backwards-compatibility with
-            //     2.11, wrt "FromStringDeserializer" supported types
-            if (targetType == LogicalType.OtherScalar) {
-                return CoercionAction.TryConvert;
-            }
             // But block from allowing structured types like POJOs, Maps etc
             return CoercionAction.Fail;
         }
@@ -326,6 +328,8 @@ public CoercionAction findCoercionFromBlankString(DeserializationConfig config,
         return actionIfBlankNotAllowed;
     }
 
+    // Whether this is "classic" scalar; a strict small subset and does NOT
+    // include "OtherScalar"
     protected boolean _isScalarType(LogicalType targetType) {
         return (targetType == LogicalType.Float)
                 || (targetType == LogicalType.Integer)

diff --git a/src/test/java/com/fasterxml/jackson/databind/deser/jdk/LocaleDeser4009Test.java b/src/test/java/com/fasterxml/jackson/databind/deser/jdk/LocaleDeser4009Test.java
@@ -19,7 +19,10 @@ public void testLocaleWithFeatureDisabled() throws Exception
 
     public void testLocaleWithFeatureEnabled() throws Exception 
     {
-        assertNull(MAPPER.readerFor(Locale.class)
+        // 06-Jul-2023, tatu: as per [databind#4009] should not become 'null'
+        //   just because
+        assertEquals(Locale.ROOT,
+            MAPPER.readerFor(Locale.class)
                 .with(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT)
                     .readValue("\"\""));
     }