From f628dc955520bc53adf520a4193fe9e85634611b Mon Sep 17 00:00:00 2001
From: Michael Vorburger <vorburger@google.com>
Date: Tue, 7 Oct 2025 21:08:18 +0200
Subject: [PATCH] fix: Allow injecting ObjectMapper in FunctionTool, default to
 ObjectMapper (re. #473)

---
 .../com/google/adk/tools/FunctionTool.java    | 32 +++++++++++--------
 1 file changed, 18 insertions(+), 14 deletions(-)

diff --git a/core/src/main/java/com/google/adk/tools/FunctionTool.java b/core/src/main/java/com/google/adk/tools/FunctionTool.java
index 3037ef40..95be3bf0 100644
--- a/core/src/main/java/com/google/adk/tools/FunctionTool.java
+++ b/core/src/main/java/com/google/adk/tools/FunctionTool.java
@@ -18,7 +18,7 @@
 
 import com.fasterxml.jackson.core.type.TypeReference;
 import com.fasterxml.jackson.databind.ObjectMapper;
-import com.fasterxml.jackson.datatype.jdk8.Jdk8Module;
+import com.google.adk.JsonBaseModel;
 import com.google.adk.agents.InvocationContext;
 import com.google.common.collect.ImmutableList;
 import com.google.common.collect.ImmutableMap;
@@ -42,13 +42,13 @@
 
 /** FunctionTool implements a customized function calling tool. */
 public class FunctionTool extends BaseTool {
-  private static final ObjectMapper OBJECT_MAPPER =
-      new ObjectMapper().registerModule(new Jdk8Module());
+
   private static final Logger logger = LoggerFactory.getLogger(FunctionTool.class);
 
   @Nullable private final Object instance;
   private final Method func;
   private final FunctionDeclaration funcDeclaration;
+  private final ObjectMapper objectMapper;
 
   public static FunctionTool create(Object instance, Method func) {
     if (!areParametersAnnotatedWithSchema(func) && wasCompiledWithDefaultParameterNames(func)) {
@@ -123,6 +123,11 @@ private static boolean wasCompiledWithDefaultParameterNames(Method func) {
   }
 
   protected FunctionTool(@Nullable Object instance, Method func, boolean isLongRunning) {
+    this(instance, func, isLongRunning, JsonBaseModel.getMapper());
+  }
+
+  protected FunctionTool(
+      @Nullable Object instance, Method func, boolean isLongRunning, ObjectMapper objectMapper) {
     super(
         func.isAnnotationPresent(Annotations.Schema.class)
                 && !func.getAnnotation(Annotations.Schema.class).name().isEmpty()
@@ -144,6 +149,7 @@ protected FunctionTool(@Nullable Object instance, Method func, boolean isLongRun
     this.funcDeclaration =
         FunctionCallingUtils.buildFunctionDeclaration(
             this.func, ImmutableList.of("toolContext", "inputStream"));
+    this.objectMapper = objectMapper;
   }
 
   @Override
@@ -225,7 +231,7 @@ private Maybe<Map<String, Object>> call(Map<String, Object> args, ToolContext to
           continue;
         }
       } else if (argValue instanceof Map) {
-        arguments[i] = OBJECT_MAPPER.convertValue(argValue, paramType);
+        arguments[i] = objectMapper.convertValue(argValue, paramType);
         continue;
       }
       arguments[i] = castValue(argValue, paramType);
@@ -236,16 +242,14 @@ private Maybe<Map<String, Object>> call(Map<String, Object> args, ToolContext to
     } else if (result instanceof Maybe) {
       return ((Maybe<?>) result)
           .map(
-              data ->
-                  OBJECT_MAPPER.convertValue(data, new TypeReference<Map<String, Object>>() {}));
+              data -> objectMapper.convertValue(data, new TypeReference<Map<String, Object>>() {}));
     } else if (result instanceof Single) {
       return ((Single<?>) result)
-          .map(
-              data -> OBJECT_MAPPER.convertValue(data, new TypeReference<Map<String, Object>>() {}))
+          .map(data -> objectMapper.convertValue(data, new TypeReference<Map<String, Object>>() {}))
           .toMaybe();
     } else {
       return Maybe.just(
-          OBJECT_MAPPER.convertValue(result, new TypeReference<Map<String, Object>>() {}));
+          objectMapper.convertValue(result, new TypeReference<Map<String, Object>>() {}));
     }
   }
 
@@ -291,7 +295,7 @@ public Flowable<Map<String, Object>> callLive(
           continue;
         }
       } else if (argValue instanceof Map) {
-        arguments[i] = OBJECT_MAPPER.convertValue(argValue, paramType);
+        arguments[i] = objectMapper.convertValue(argValue, paramType);
         continue;
       }
       arguments[i] = castValue(argValue, paramType);
@@ -305,7 +309,7 @@ public Flowable<Map<String, Object>> callLive(
     }
   }
 
-  private static List<Object> createList(List<Object> values, Class<?> type) {
+  private List<Object> createList(List<Object> values, Class<?> type) {
     List<Object> list = new ArrayList<>();
     // List of parameterized type is not supported.
     if (type == null) {
@@ -321,13 +325,13 @@ private static List<Object> createList(List<Object> values, Class<?> type) {
           || cls == String.class) {
         list.add(castValue(value, cls));
       } else {
-        list.add(OBJECT_MAPPER.convertValue(value, type));
+        list.add(objectMapper.convertValue(value, type));
       }
     }
     return list;
   }
 
-  private static Object castValue(Object value, Class<?> type) {
+  private Object castValue(Object value, Class<?> type) {
     if (type.equals(Integer.class) || type.equals(int.class)) {
       if (value instanceof Integer) {
         return value;
@@ -372,6 +376,6 @@ private static Object castValue(Object value, Class<?> type) {
         return value;
       }
     }
-    return OBJECT_MAPPER.convertValue(value, type);
+    return objectMapper.convertValue(value, type);
   }
 }