DataConvertor Argument Deserialization: Use defaults for missing arguments and ignore additional arguments (#184)

 Use defaults for missing arguments and ignore additional arguments on workflow method invocation (#184)

Author: halakaraki

src/main/java/com/uber/cadence/converter/JsonDataConverter.java

@@ -17,6 +17,7 @@
 
 package com.uber.cadence.converter;
 
+import com.google.common.base.Defaults;
 import com.google.common.collect.ImmutableSet;
 import com.google.gson.Gson;
 import com.google.gson.GsonBuilder;
@@ -162,10 +163,29 @@ public Object[] fromDataArray(byte[] content, Type... valueTypes) throws DataCon
         Object result = gson.fromJson(new String(content, StandardCharsets.UTF_8), valueTypes[0]);
         return new Object[] {result};
       }
-      JsonArray array = parser.parse(new String(content, StandardCharsets.UTF_8)).getAsJsonArray();
+
+      JsonElement element = parser.parse(new String(content, StandardCharsets.UTF_8));
+      JsonArray array;
+      if (element instanceof JsonArray) {
+        array = element.getAsJsonArray();
+      } else {
+        array = new JsonArray();
+        array.add(element);
+      }
+
       Object[] result = new Object[valueTypes.length];
       for (int i = 0; i < valueTypes.length; i++) {
-        result[i] = gson.fromJson(array.get(i), valueTypes[i]);
+
+        if (i >= array.size()) { // Missing arugments => add defaults
+          Type t = valueTypes[i];
+          if (t instanceof Class) {
+            result[i] = Defaults.defaultValue((Class<?>) t);
+          } else {
+            result[i] = null;
+          }
+        } else {
+          result[i] = gson.fromJson(array.get(i), valueTypes[i]);
+        }
       }
       return result;
     } catch (DataConverterException e) {

src/test/java/com/uber/cadence/converter/JsonDataConverterTest.java

@@ -75,6 +75,46 @@ public void testUUIDList() throws NoSuchMethodException {
     assertEquals(result.toString(), list, result);
   }
 
+  public static void threeArguments(int one, int two, String three) {}
+
+  public static void aLotOfArguments(int one, int two, String three, Object obj, int[] intArr) {}
+
+  @Test
+  public void AdditionalInputArgumentsAreIgnored() throws NoSuchMethodException {
+    Method m =
+        JsonDataConverterTest.class.getDeclaredMethod(
+            "threeArguments", int.class, int.class, String.class);
+    Type[] arg = m.getGenericParameterTypes();
+
+    DataConverter converter = JsonDataConverter.getInstance();
+    byte[] data = converter.toData(1, 2, "a string", "an extra string :o!!!");
+    @SuppressWarnings("unchecked")
+    Object[] deserializedArguments = converter.fromDataArray(data, arg);
+    assertEquals(3, deserializedArguments.length);
+    assertEquals(1, (int) deserializedArguments[0]);
+    assertEquals(2, (int) deserializedArguments[1]);
+    assertEquals("a string", deserializedArguments[2]);
+  }
+
+  @Test
+  public void MissingInputArgumentsArePopulatedWithDefaultValues() throws NoSuchMethodException {
+    Method m =
+        JsonDataConverterTest.class.getDeclaredMethod(
+            "aLotOfArguments", int.class, int.class, String.class, Object.class, int[].class);
+    Type[] arg = m.getGenericParameterTypes();
+
+    DataConverter converter = JsonDataConverter.getInstance();
+    byte[] data = converter.toData(1);
+    @SuppressWarnings("unchecked")
+    Object[] deserializedArguments = converter.fromDataArray(data, arg);
+    assertEquals(5, deserializedArguments.length);
+    assertEquals(1, (int) deserializedArguments[0]);
+    assertEquals(0, (int) deserializedArguments[1]);
+    assertEquals(null, deserializedArguments[2]);
+    assertEquals(null, deserializedArguments[3]);
+    assertEquals(null, deserializedArguments[4]);
+  }
+
   @Test
   public void testClass() {
     DataConverter converter = JsonDataConverter.getInstance();