feat(serialization): Avoid ser/deser roundtripping asymmetry for Object map value type

Author: padamstx

src/main/java/com/ibm/cloud/sdk/core/util/DynamicModelTypeAdapterFactory.java

@@ -296,11 +296,13 @@ public static class Adapter<T> extends TypeAdapter<T> {
     private Constructor<?> ctor;
     private Map<String, BoundField> boundFields;
     private Gson gson;
+    private TypeAdapter<?> mapValueObjectTypeAdapter;
 
     Adapter(Gson gson, Constructor<?> ctor, Map<String, BoundField> boundFields) {
       this.gson = gson;
       this.ctor = ctor;
       this.boundFields = boundFields;
+      this.mapValueObjectTypeAdapter = new MapValueObjectTypeAdapter(gson);
     }
 
     /*
@@ -326,9 +328,18 @@ public void write(JsonWriter out, T value) throws IOException {
           }
         }
 
+        // Next, we need to dynamically retrieve the additionalPropertyTypeToken field
+        // from the DynamicModel instance and retrieve its TypeAdapter for deserializing arbitrary properties.
         TypeToken<?> mapValueType = getMapValueType(value);
         TypeAdapter mapValueTypeAdapter = gson.getAdapter(mapValueType);
 
+        // If the map value type is Object, then we need to use our own flavor of the Gson ObjectTypeAdapter.
+        if (mapValueType.getRawType().equals(Object.class)) {
+          mapValueTypeAdapter = this.mapValueObjectTypeAdapter;
+        } else {
+          mapValueTypeAdapter = gson.getAdapter(mapValueType);
+        }
+
         // Next, serialize each of the map entries.
         for (String key : ((DynamicModel<?>) value).getPropertyNames()) {
           out.name(String.valueOf(key));
@@ -364,9 +375,16 @@ public T read(JsonReader in) throws IOException {
       }
 
       // Next, we need to dynamically retrieve the additionalPropertyTypeToken field
-      // from the DynamicModel instance and retrieve its TypeAdapter.
+      // from the DynamicModel instance and retrieve its TypeAdapter for deserializing arbitrary properties.
       TypeToken<?> mapValueType = getMapValueType(instance);
-      TypeAdapter<?> mapValueTypeAdapter = gson.getAdapter(mapValueType);
+      TypeAdapter<?> mapValueTypeAdapter;
+
+      // If the map value type is Object, then we need to use our own flavor of the Gson ObjectTypeAdapter.
+      if (mapValueType.getRawType().equals(Object.class)) {
+        mapValueTypeAdapter = this.mapValueObjectTypeAdapter;
+      } else {
+        mapValueTypeAdapter = gson.getAdapter(mapValueType);
+      }
 
       try {
         in.beginObject();
@@ -386,6 +404,8 @@ public T read(JsonReader in) throws IOException {
             // Otherwise, it must be an additional property so it belongs in the map.
             String key = name;
             Object value = mapValueTypeAdapter.read(in);
+
+            // Now add the arbitrary property/value to the map.
             Object replaced = ((DynamicModel) instance).put(key, value);
 
             // If this new map entry is replacing an existing entry, then we must have a duplicate.

src/main/java/com/ibm/cloud/sdk/core/util/GsonSingleton.java

@@ -16,6 +16,8 @@
 
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
+import com.google.gson.internal.LazilyParsedNumber;
+import com.google.gson.internal.bind.TypeAdapters;
 
 /**
  * Gson singleton to be use when transforming from JSON to Java Objects and vise versa. It handles date formatting and
@@ -52,8 +54,13 @@ private static void registerTypeAdapters(GsonBuilder builder) {
     // Date serializer and deserializer
     builder.registerTypeAdapter(Date.class, new DateDeserializer());
     builder.registerTypeAdapter(Date.class, new DateSerializer());
+
+    // Make sure that byte[] ser/deser includes base64 encoding/decoding.
     builder.registerTypeAdapter(byte[].class, new ByteArrayTypeAdapter());
 
+    // Make sure we serialize LazilyParsedNumber properly to avoid unnecessary decimal places in serialized integers.
+    builder.registerTypeAdapter(LazilyParsedNumber.class, TypeAdapters.NUMBER);
+
     // Type adapter factory for DynamicModel subclasses.
     builder.registerTypeAdapterFactory(new DynamicModelTypeAdapterFactory());
   }

src/main/java/com/ibm/cloud/sdk/core/util/MapValueObjectTypeAdapter.java

@@ -0,0 +1,119 @@
+/**
+ * Copyright 2019 IBM Corp. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in compliance with
+ * the License. You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software distributed under the License is distributed on
+ * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the License for the
+ * specific language governing permissions and limitations under the License.
+ */
+
+/*
+ * Copyright (C) 2011 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package com.ibm.cloud.sdk.core.util;
+
+import java.io.IOException;
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Map;
+
+import com.google.gson.Gson;
+import com.google.gson.TypeAdapter;
+import com.google.gson.internal.LazilyParsedNumber;
+import com.google.gson.internal.LinkedTreeMap;
+import com.google.gson.internal.bind.ObjectTypeAdapter;
+import com.google.gson.stream.JsonReader;
+import com.google.gson.stream.JsonToken;
+import com.google.gson.stream.JsonWriter;
+
+/**
+ * This class is adapted from the ObjectTypeAdapter from the GSON project.
+ * When de-serializing a dynamic model, when we encounter an arbitrary property that is an object,
+ * we'll use this type adapter instead of GSON's ObjectTypeAdapter.
+ * This will ensure that the LazilyParsedNumber class is used to represent JSON number fields within
+ * the object instead of Double.
+ *
+ * Adapts types whose static type is only 'Object'. Uses getClass() on
+ * serialization and a primitive/Map/List on deserialization.
+ */
+public final class MapValueObjectTypeAdapter extends TypeAdapter<Object> {
+  private final Gson gson;
+
+  MapValueObjectTypeAdapter(Gson gson) {
+    this.gson = gson;
+  }
+
+  @Override public Object read(JsonReader in) throws IOException {
+    JsonToken token = in.peek();
+    switch (token) {
+    case BEGIN_ARRAY:
+      List<Object> list = new ArrayList<Object>();
+      in.beginArray();
+      while (in.hasNext()) {
+        list.add(read(in));
+      }
+      in.endArray();
+      return list;
+
+    case BEGIN_OBJECT:
+      Map<String, Object> map = new LinkedTreeMap<String, Object>();
+      in.beginObject();
+      while (in.hasNext()) {
+        map.put(in.nextName(), read(in));
+      }
+      in.endObject();
+      return map;
+
+    case STRING:
+      return in.nextString();
+
+    case NUMBER:
+      // Use LazilyParsedNumber instead of Double for a JSON number value.
+      return new LazilyParsedNumber(in.nextString());
+
+    case BOOLEAN:
+      return in.nextBoolean();
+
+    case NULL:
+      in.nextNull();
+      return null;
+
+    default:
+      throw new IllegalStateException();
+    }
+  }
+
+  @SuppressWarnings("unchecked")
+  @Override public void write(JsonWriter out, Object value) throws IOException {
+    if (value == null) {
+      out.nullValue();
+      return;
+    }
+
+    TypeAdapter<Object> typeAdapter = (TypeAdapter<Object>) gson.getAdapter(value.getClass());
+    if (typeAdapter instanceof ObjectTypeAdapter) {
+      out.beginObject();
+      out.endObject();
+      return;
+    }
+
+    typeAdapter.write(out, value);
+  }
+}

src/test/java/com/ibm/cloud/sdk/core/test/model/DynamicModelSerializationTest.java

@@ -52,7 +52,7 @@ private <T> T deserialize(String json, Class<T> clazz) {
     return GsonSingleton.getGson().fromJson(json, clazz);
   }
 
-  private <T> void testSerDeser(DynamicModel<?> model, Class<T> clazz, boolean trimDecimals) {
+  private <T> void testSerDeser(DynamicModel<?> model, Class<T> clazz) {
     String jsonString = serialize(model);
     if (displayOutput) {
       System.out.println("serialized " + model.getClass().getSimpleName() + ": " + jsonString);
@@ -61,12 +61,7 @@ private <T> void testSerDeser(DynamicModel<?> model, Class<T> clazz, boolean tri
     if (displayOutput) {
       System.out.println("de-serialized " + model.getClass().getSimpleName() + ": " + newModel.toString());
     }
-    if (trimDecimals) {
-      String deserString = newModel.toString().replaceAll(".0", "");
-      assertEquals(deserString, jsonString);
-    } else {
-      assertEquals(newModel, model);
-    }
+    assertEquals(newModel, model);
   }
 
   private ModelAPFoo createModelAPFoo() {
@@ -164,7 +159,7 @@ private ModelAPObject createModelAPObject() {
   public void testModelAPFoo() {
     ModelAPFoo model = createModelAPFoo();
     // model.put("basketball", "foo");
-    testSerDeser(model, ModelAPFoo.class, false);
+    testSerDeser(model, ModelAPFoo.class);
   }
 
   @Test
@@ -207,7 +202,7 @@ public void testNullValues() {
     ModelAPFoo model = createModelAPFoo();
     model.setProp1(null);
     // model.put("basketball", "foo");
-    testSerDeser(model, ModelAPFoo.class, false);
+    testSerDeser(model, ModelAPFoo.class);
   }
 
   @Test(expectedExceptions = {JsonSyntaxException.class})
@@ -242,26 +237,26 @@ public void testCtorExcp() {
   public void testModelAPInteger() {
     ModelAPInteger model = createModelAPInteger();
     // model.put("basketball", "foo");
-    testSerDeser(model, ModelAPInteger.class, false);
+    testSerDeser(model, ModelAPInteger.class);
   }
 
   @Test
   public void testModelAPObject() {
     ModelAPObject model = createModelAPObject();
-    testSerDeser(model, ModelAPObject.class, true);
+    testSerDeser(model, ModelAPObject.class);
   }
 
   @Test
   public void testModelAPString() {
     ModelAPString model = createModelAPString();
     // model.put("basketball", Integer.valueOf(33));
-    testSerDeser(model, ModelAPString.class, false);
+    testSerDeser(model, ModelAPString.class);
   }
 
   @Test
   public void testModelAPFooNullTypeToken() {
     ModelAPFooNullTypeToken model = createModelAPFooNullTypeToken();
-    testSerDeser(model, ModelAPFooNullTypeToken.class, true);
+    testSerDeser(model, ModelAPFooNullTypeToken.class);
   }
 
   @Test
@@ -275,7 +270,7 @@ public void testModelAPFooNull() {
   public void testModelAPProtectedCtor() {
     ModelAPProtectedCtor model = createModelAPProtectedCtor();
     // model.put("basketball", Integer.valueOf(33));
-    testSerDeser(model, ModelAPProtectedCtor.class, false);
+    testSerDeser(model, ModelAPProtectedCtor.class);
   }
 
   @Test(expectedExceptions = {JsonSyntaxException.class}, expectedExceptionsMessageRegExp="Duplicate key: baseball")