fix: Fix invoker to work when using dataclass with from_dict but dataclass… (#9434)

* Fix invoker to work when using dataclass with from_dict but dataclass is already given

* add reno

* Add unit test

* Remove line

Author: sjrl

haystack/tools/component_tool.py

@@ -159,15 +159,19 @@ def component_invoker(**kwargs):
                 target_type = get_args(param_type)[0] if get_origin(param_type) is list else param_type
                 if hasattr(target_type, "from_dict"):
                     if isinstance(param_value, list):
-                        param_value = [target_type.from_dict(item) for item in param_value if isinstance(item, dict)]
+                        resolved_param_value = [
+                            target_type.from_dict(item) if isinstance(item, dict) else item for item in param_value
+                        ]
                     elif isinstance(param_value, dict):
-                        param_value = target_type.from_dict(param_value)
+                        resolved_param_value = target_type.from_dict(param_value)
+                    else:
+                        resolved_param_value = param_value
                 else:
                     # Let TypeAdapter handle both single values and lists
                     type_adapter = TypeAdapter(param_type)
-                    param_value = type_adapter.validate_python(param_value)
+                    resolved_param_value = type_adapter.validate_python(param_value)
 
-                converted_kwargs[param_name] = param_value
+                converted_kwargs[param_name] = resolved_param_value
             logger.debug(f"Invoking component {type(component)} with kwargs: {converted_kwargs}")
             return component.run(**converted_kwargs)
 

releasenotes/notes/fix-component-invoker-dataclass-2efe773f03df8a93.yaml

@@ -0,0 +1,5 @@
+---
+fixes:
+  - |
+    Fix component_invoker used by ComponentTool to work when a dataclass like ChatMessage is directly passed to `component_tool.invoke(...)`.
+    Previously this would either cause an error or silently skip your input.

test/tools/test_component_tool.py

@@ -30,6 +30,21 @@
 # Component and Model Definitions
 
 
+@component
+class SimpleComponentUsingChatMessages:
+    """A simple component that generates text."""
+
+    @component.output_types(reply=str)
+    def run(self, messages: List[ChatMessage]) -> Dict[str, str]:
+        """
+        A simple component that generates text.
+
+        :param messages: Users messages
+        :return: A dictionary with the generated text.
+        """
+        return {"reply": f"Hello, {messages[0].text}!"}
+
+
 @component
 class SimpleComponent:
     """A simple component that generates text."""
@@ -306,6 +321,13 @@ def foo(self, text: str):
         with pytest.raises(ValueError):
             ComponentTool(component=not_a_component, name="invalid_tool", description="This should fail")
 
+    def test_component_invoker_with_chat_message_input(self):
+        tool = ComponentTool(
+            component=SimpleComponentUsingChatMessages(), name="simple_tool", description="A simple tool"
+        )
+        result = tool.invoke(messages=[ChatMessage.from_user(text="world")])
+        assert result == {"reply": "Hello, world!"}
+
 
 # Integration tests
 class TestToolComponentInPipelineWithOpenAI: