Fix #2236

release-notes/VERSION-2.x

@@ -33,6 +33,8 @@ Project: jackson-databind
  (reported by RightHandedMonkey@github)
 #2230: `WRITE_BIGDECIMAL_AS_PLAIN` is ignored if `@JsonFormat` is used
  (reported by Pavel C)
+#2236: Type id not provided on `Double.NaN`, `Infinity` with `@JsonTypeInfo`
+ (reported by C-B-B@github)
 #2241: Add `JsonPropertyNamingStrategy.LOWER_DOT_CASE` for dot-delimited names
  (contributed by [email protected])
 

src/main/java/com/fasterxml/jackson/databind/ser/std/NumberSerializers.java

@@ -7,7 +7,7 @@
 import com.fasterxml.jackson.annotation.JsonFormat;
 
 import com.fasterxml.jackson.core.*;
-
+import com.fasterxml.jackson.core.type.WritableTypeId;
 import com.fasterxml.jackson.databind.*;
 import com.fasterxml.jackson.databind.annotation.JacksonStdImpl;
 import com.fasterxml.jackson.databind.jsonFormatVisitors.JsonFormatVisitorWrapper;
@@ -220,11 +220,27 @@ public void serialize(Object value, JsonGenerator gen,
 
         // IMPORTANT: copied from `NonTypedScalarSerializerBase`
         @Override
-        public void serializeWithType(Object value, JsonGenerator gen,
+        public void serializeWithType(Object value, JsonGenerator g,
                 SerializerProvider provider, TypeSerializer typeSer)
                 throws IOException {
             // no type info, just regular serialization
-            serialize(value, gen, provider);
+            // 08-Feb-2018, tatu: Except that as per [databind#2236], NaN values need
+            //    special handling
+            Double d = (Double) value;
+            if (notFinite(d)) {
+                WritableTypeId typeIdDef = typeSer.writeTypePrefix(g,
+                        // whether to indicate it's number or string is arbitrary; important it is scalar
+                        typeSer.typeId(value, JsonToken.VALUE_NUMBER_FLOAT));
+                g.writeNumber(d);
+                typeSer.writeTypeSuffix(g, typeIdDef);
+            } else {
+                g.writeNumber(d);
+            }
+        }
+
+        public static boolean notFinite(double value) {
+            // `jackson-core` has helper method in 3 but not yet
+            return Double.isNaN(value) || Double.isInfinite(value);
         }
     }
 }

src/test/java/com/fasterxml/jackson/databind/BaseMapTest.java

@@ -77,7 +77,8 @@ public StringWrapper(String value) {
 
     protected static class ObjectWrapper {
         final Object object;
-        protected ObjectWrapper(final Object object) {
+
+        public ObjectWrapper(final Object object) {
             this.object = object;
         }
         public Object getObject() { return object; }

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

@@ -23,6 +23,18 @@ static class Data {
         public long key;
     }
 
+    // Basic `ObjectWrapper` from base uses delegating ctor, won't work well; should
+    // figure out why, but until then we'll use separate impl
+    protected static class ObjectWrapperForPoly {
+        Object object;
+
+        protected ObjectWrapperForPoly() { }
+        public ObjectWrapperForPoly(final Object o) {
+            object = o;
+        }
+        public Object getObject() { return object; }
+    }
+
     /*
     /**********************************************************************
     /* Test methods
@@ -128,4 +140,15 @@ public void testDefaultTypingWithLong() throws Exception
         assertNotNull(result);
         assertEquals(2, result.size());
     }
+
+    // [databind#2236]: do need type info for NaN
+    public void testDefaultTypingWithNaN() throws Exception
+    {
+        final ObjectWrapperForPoly INPUT = new ObjectWrapperForPoly(Double.POSITIVE_INFINITY);
+        final String json = DEFAULT_TYPING_MAPPER.writeValueAsString(INPUT);
+        final ObjectWrapperForPoly result = DEFAULT_TYPING_MAPPER.readValue(json, ObjectWrapperForPoly.class);
+        assertEquals(Double.class, result.getObject().getClass());
+        assertEquals(INPUT.getObject().toString(), result.getObject().toString());
+        assertTrue(((Double) result.getObject()).isInfinite());
+    }
 }