Support READ_UNKNOWN_ENUM_VALUES_AS_NULL with @JsonCreator

The deserialization feature READ_UNKNOWN_ENUM_VALUES_AS_NULL allows enum
values that are not recognised to take a null value when parsed. Before
this commit, this deserialization feature did not work whenever an enum
had a method marked @JsonCreator, and the enum creator method itself had
to choose null in the case of unknown input.

With this change, if an enum creator method throws an
IllegalArgumentException then this is considered to be an unknown value
and (if READ_UNKNOWN_ENUM_VALUES_AS_NULL is active) then null will be
used.

Author: joelittlejohn

src/main/java/com/fasterxml/jackson/databind/deser/std/FactoryBasedEnumDeserializer.java

@@ -134,6 +134,12 @@ public Object deserialize(JsonParser p, DeserializationContext ctxt) throws IOEx
             return _factory.callOnWith(_valueClass, value);
         } catch (Exception e) {
             Throwable t = ClassUtil.throwRootCauseIfIOE(e);
+
+            if (ctxt.isEnabled(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL) &&
+                    t instanceof IllegalArgumentException) {
+                return null;
+            }
+
             return ctxt.handleInstantiationProblem(_valueClass, value, t);
         }
     }

src/test/java/com/fasterxml/jackson/databind/deser/jdk/EnumDeserializationTest.java

@@ -116,6 +116,17 @@ static enum EnumWithDefaultAnnoAndConstructor {
         }
     }
 
+    static enum StrictEnumCreator {
+        A, B;
+
+        @JsonCreator public static StrictEnumCreator fromId(String value) {
+            for (StrictEnumCreator e: values()) {
+                if (e.name().toLowerCase().equals(value)) return e;
+            }
+            throw new IllegalArgumentException(value);
+        }
+    }
+
     // // 
 
     public enum AnEnum {
@@ -321,6 +332,16 @@ public void testAllowUnknownEnumValuesReadAsNull() throws Exception
         assertNull(reader.forType(TestEnum.class).readValue(" 4343 "));
     }
 
+    // Ability to ignore unknown Enum values:
+
+    public void testAllowUnknownEnumValuesReadAsNullWithCreatorMethod() throws Exception
+    {
+        // can not use shared mapper when changing configs...
+        ObjectReader reader = MAPPER.reader(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL);
+        assertNull(reader.forType(StrictEnumCreator.class).readValue("\"NO-SUCH-VALUE\""));
+        assertNull(reader.forType(StrictEnumCreator.class).readValue(" 4343 "));
+    }
+
     public void testAllowUnknownEnumValuesForEnumSets() throws Exception
     {
         ObjectReader reader = MAPPER.reader(DeserializationFeature.READ_UNKNOWN_ENUM_VALUES_AS_NULL);