Add new DefaultTyping.NON_FINAL_AND_ENUMS to allow default type handler for Enums (#4159)

Author: JooHyukKim

src/main/java/com/fasterxml/jackson/databind/ObjectMapper.java

@@ -189,6 +189,16 @@ public enum DefaultTyping {
          */
         NON_FINAL,
 
+        /**
+         * Enables default typing for non-final types as {@link #NON_FINAL},
+         * but also includes Enums.
+         * Designed to allow default typing of Enums without resorting to
+         * {@link #EVERYTHING}, which has security implications.
+         *<p>
+         * @since 2.16
+         */
+        NON_FINAL_AND_ENUMS,
+
         /**
          * Value that means that default typing will be used for
          * all types, with exception of small number of
@@ -355,6 +365,20 @@ public boolean useForType(JavaType t)
                 }
                 // [databind#88] Should not apply to JSON tree models:
                 return !t.isFinal() && !TreeNode.class.isAssignableFrom(t.getRawClass());
+
+            case NON_FINAL_AND_ENUMS: // since 2.16
+                while (t.isArrayType()) {
+                    t = t.getContentType();
+                }
+                // 19-Apr-2016, tatu: ReferenceType like Optional also requires similar handling:
+                while (t.isReferenceType()) {
+                    t = t.getReferencedType();
+                }
+                // [databind#88] Should not apply to JSON tree models:
+                return (!t.isFinal() && !TreeNode.class.isAssignableFrom(t.getRawClass()))
+                        // [databind#3569] Allow use of default typing for Enums
+                        || t.isEnumType();
+
             case EVERYTHING:
                 // So, excluding primitives (handled earlier) and "Natural types" (handled
                 // before this method is called), applied to everything

src/test/java/com/fasterxml/jackson/databind/jsontype/deftyping/TestDefaultForEnums.java

@@ -1,5 +1,11 @@
 package com.fasterxml.jackson.databind.jsontype.deftyping;
 
+import com.fasterxml.jackson.annotation.JsonCreator;
+import com.fasterxml.jackson.annotation.JsonTypeInfo;
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.core.type.TypeReference;
+import com.fasterxml.jackson.databind.JavaType;
+import com.fasterxml.jackson.databind.jsontype.DefaultBaseTypeLimitingValidator;
 import java.util.concurrent.TimeUnit;
 
 import com.fasterxml.jackson.databind.BaseMapTest;
@@ -26,6 +32,25 @@ protected static class TimeUnitBean {
         public TimeUnit timeUnit;
     }
 
+    static class Foo3569<T> {
+        public T item;
+    }
+
+    enum Bar3569 {
+        ENABLED, DISABLED, HIDDEN;
+
+        @JsonCreator
+        public static Bar3569 fromValue(String value) {
+            String upperVal = value.toUpperCase();
+            for (Bar3569 enumValue : Bar3569.values()) {
+                if (enumValue.name().equals(upperVal)) {
+                    return enumValue;
+                }
+            }
+            throw new IllegalArgumentException("Bad input [" + value + "]");
+        }
+    }
+
     /*
     /**********************************************************
     /* Test methods
@@ -78,4 +103,32 @@ public void testSimpleEnumsAsField() throws Exception
         EnumHolder holder = m.readValue(json, EnumHolder.class);
         assertSame(TestEnum.B, holder.value);
     }
+
+    /**
+     * [databind#3569]: Unable to deserialize enum object with default-typed
+     * {@link com.fasterxml.jackson.annotation.JsonTypeInfo.As#WRAPPER_ARRAY} and {@link JsonCreator} together,
+     *
+     * @since 2.16
+     */
+    public void testEnumAsWrapperArrayWithCreator() throws JsonProcessingException
+    {
+        ObjectMapper objectMapper = jsonMapperBuilder()
+                .activateDefaultTyping(
+                        new DefaultBaseTypeLimitingValidator(),
+                        ObjectMapper.DefaultTyping.NON_FINAL_AND_ENUMS,
+                        JsonTypeInfo.As.WRAPPER_ARRAY)
+                .build();
+
+        Foo3569<Bar3569> expected = new Foo3569<>();
+        expected.item = Bar3569.ENABLED;
+
+        // First, serialize
+        String serialized = objectMapper.writeValueAsString(expected);
+
+        // Then, deserialize with TypeReference
+        assertNotNull(objectMapper.readValue(serialized, new TypeReference<Foo3569<Bar3569>>() {}));
+        // And, also try as described in [databind#3569]
+        JavaType javaType = objectMapper.getTypeFactory().constructParametricType(Foo3569.class, new Class[]{Bar3569.class});
+        assertNotNull(objectMapper.readValue(serialized, javaType));
+    }
 }