feat: GenAI - Added the GenerativeModel.start_chat(response_validation: bool = True) parameter

The error messages are now more informative.

The use of the `raise_on_blocked` parameter has been deprecated. Use `response_validation` instead.

PiperOrigin-RevId: 607188491

Author: Ark-kun

tests/unit/vertexai/test_generative_models.py

@@ -120,6 +120,23 @@ def mock_generate_content(
     model: Optional[str] = None,
     contents: Optional[MutableSequence[gapic_content_types.Content]] = None,
 ) -> Iterable[gapic_prediction_service_types.GenerateContentResponse]:
+    last_message_part = request.contents[-1].parts[0]
+    should_fail = last_message_part.text and "Please fail" in last_message_part.text
+    if should_fail:
+        response = gapic_prediction_service_types.GenerateContentResponse(
+            candidates=[
+                gapic_content_types.Candidate(
+                    finish_reason=gapic_content_types.Candidate.FinishReason.SAFETY,
+                    finish_message="Failed due to: " + last_message_part.text,
+                    safety_ratings=[
+                        gapic_content_types.SafetyRating(rating)
+                        for rating in _RESPONSE_SAFETY_RATINGS_STRUCT
+                    ],
+                ),
+            ],
+        )
+        return response
+
     is_continued_chat = len(request.contents) > 1
     has_retrieval = any(
         tool.retrieval or tool.google_search_retrieval for tool in request.tools
@@ -281,6 +298,29 @@ def test_chat_send_message(self, generative_models: generative_models):
         response2 = chat.send_message("Is sky blue on other planets?")
         assert response2.text
 
+    @mock.patch.object(
+        target=prediction_service.PredictionServiceClient,
+        attribute="generate_content",
+        new=mock_generate_content,
+    )
+    @pytest.mark.parametrize(
+        "generative_models",
+        [generative_models, preview_generative_models],
+    )
+    def test_chat_send_message_response_validation_errors(
+        self, generative_models: generative_models
+    ):
+        model = generative_models.GenerativeModel("gemini-pro")
+        chat = model.start_chat()
+        response1 = chat.send_message("Why is sky blue?")
+        assert response1.text
+        assert len(chat.history) == 2
+
+        with pytest.raises(generative_models.ResponseValidationError):
+            chat.send_message("Please fail!")
+        # Checking that history did not get updated
+        assert len(chat.history) == 2
+
     @mock.patch.object(
         target=prediction_service.PredictionServiceClient,
         attribute="generate_content",

vertexai/generative_models/__init__.py

@@ -29,7 +29,7 @@
     HarmBlockThreshold,
     Image,
     Part,
-    ResponseBlockedError,
+    ResponseValidationError,
     Tool,
 )
 
@@ -46,6 +46,6 @@
     "HarmBlockThreshold",
     "Image",
     "Part",
-    "ResponseBlockedError",
+    "ResponseValidationError",
     "Tool",
 ]

vertexai/generative_models/_generative_models.py

@@ -45,6 +45,7 @@
 from vertexai.language_models import (
     _language_models as tunable_models,
 )
+import warnings
 
 try:
     from PIL import Image as PIL_Image  # pylint: disable=g-import-not-at-top
@@ -606,18 +607,28 @@ def start_chat(
         self,
         *,
         history: Optional[List["Content"]] = None,
+        response_validation: bool = True,
     ) -> "ChatSession":
         """Creates a stateful chat session.
 
         Args:
             history: Previous history to initialize the chat session.
+            response_validation: Whether to validate responses before adding
+                them to chat history. By default, `send_message` will raise
+                error if the request or response is blocked or if the response
+                is incomplete due to going over the max token limit.
+                If set to `False`, the chat session history will always
+                accumulate the request and response messages even if the
+                reponse if blocked or incomplete. This can result in an unusable
+                chat session state.
 
         Returns:
             A ChatSession object.
         """
         return ChatSession(
             model=self,
             history=history,
+            response_validation=response_validation,
         )
 
 
@@ -628,6 +639,29 @@ def start_chat(
 ]
 
 
+def _validate_response(
+    response: "GenerationResponse",
+    request_contents: Optional[List["Content"]] = None,
+    response_chunks: Optional[List["GenerationResponse"]] = None,
+) -> None:
+    candidate = response.candidates[0]
+    if candidate.finish_reason not in _SUCCESSFUL_FINISH_REASONS:
+        message = (
+            "The model response did not completed successfully.\n"
+            f"Finish reason: {candidate.finish_reason}.\n"
+            f"Finish message: {candidate.finish_message}.\n"
+            f"Safety ratings: {candidate.safety_ratings}.\n"
+            "To protect the integrity of the chat session, the request and response were not added to chat history.\n"
+            "To skip the response validation, specify `model.start_chat(response_validation=False)`.\n"
+            "Note that letting blocked or otherwise incomplete responses into chat history might lead to future interactions being blocked by the service."
+        )
+        raise ResponseValidationError(
+            message=message,
+            request_contents=request_contents,
+            responses=response_chunks,
+        )
+
+
 class ChatSession:
     """Chat session holds the chat history."""
 
@@ -639,15 +673,15 @@ def __init__(
         model: _GenerativeModel,
         *,
         history: Optional[List["Content"]] = None,
-        raise_on_blocked: bool = True,
+        response_validation: bool = True,
     ):
         if history:
             if not all(isinstance(item, Content) for item in history):
                 raise ValueError("history must be a list of Content objects.")
 
         self._model = model
         self._history = history or []
-        self._raise_on_blocked = raise_on_blocked
+        self._response_validator = _validate_response if response_validation else None
 
     @property
     def history(self) -> List["Content"]:
@@ -784,13 +818,12 @@ def _send_message(
             tools=tools,
         )
         # By default we're not adding incomplete interactions to history.
-        if self._raise_on_blocked:
-            if response.candidates[0].finish_reason not in _SUCCESSFUL_FINISH_REASONS:
-                raise ResponseBlockedError(
-                    message="The response was blocked.",
-                    request_contents=request_history,
-                    responses=[response],
-                )
+        if self._response_validator is not None:
+            self._response_validator(
+                response=response,
+                request_contents=request_history,
+                response_chunks=[response],
+            )
 
         # Adding the request and the first response candidate to history
         response_message = response.candidates[0].content
@@ -841,13 +874,13 @@ async def _send_message_async(
             tools=tools,
         )
         # By default we're not adding incomplete interactions to history.
-        if self._raise_on_blocked:
-            if response.candidates[0].finish_reason not in _SUCCESSFUL_FINISH_REASONS:
-                raise ResponseBlockedError(
-                    message="The response was blocked.",
-                    request_contents=request_history,
-                    responses=[response],
-                )
+        if self._response_validator is not None:
+            self._response_validator(
+                response=response,
+                request_contents=request_history,
+                response_chunks=[response],
+            )
+
         # Adding the request and the first response candidate to history
         response_message = response.candidates[0].content
         # Response role is NOT set by the model.
@@ -905,13 +938,12 @@ def _send_message_streaming(
             else:
                 full_response = chunk
             # By default we're not adding incomplete interactions to history.
-            if self._raise_on_blocked:
-                if chunk.candidates[0].finish_reason not in _SUCCESSFUL_FINISH_REASONS:
-                    raise ResponseBlockedError(
-                        message="The response was blocked.",
-                        request_contents=request_history,
-                        responses=chunks,
-                    )
+            if self._response_validator is not None:
+                self._response_validator(
+                    response=chunk,
+                    request_contents=request_history,
+                    response_chunks=chunks,
+                )
             yield chunk
         if not full_response:
             return
@@ -973,16 +1005,13 @@ async def async_generator():
                 else:
                     full_response = chunk
                 # By default we're not adding incomplete interactions to history.
-                if self._raise_on_blocked:
-                    if (
-                        chunk.candidates[0].finish_reason
-                        not in _SUCCESSFUL_FINISH_REASONS
-                    ):
-                        raise ResponseBlockedError(
-                            message="The response was blocked.",
-                            request_contents=request_history,
-                            responses=chunks,
-                        )
+                if self._response_validator is not None:
+                    self._response_validator(
+                        response=chunk,
+                        request_contents=request_history,
+                        response_chunks=chunks,
+                    )
+
                 yield chunk
             if not full_response:
                 return
@@ -996,6 +1025,36 @@ async def async_generator():
         return async_generator()
 
 
+class _PreviewChatSession(ChatSession):
+    __doc__ = ChatSession.__doc__
+
+    # This class preserves backwards compatibility with the `raise_on_blocked` parameter.
+
+    def __init__(
+        self,
+        model: _GenerativeModel,
+        *,
+        history: Optional[List["Content"]] = None,
+        response_validation: bool = True,
+        # Deprecated
+        raise_on_blocked: Optional[bool] = None,
+    ):
+        if raise_on_blocked is not None:
+            warnings.warn(
+                message="Use `response_validation` instead of `raise_on_blocked`."
+            )
+            if response_validation is not None:
+                raise ValueError(
+                    "Cannot use `response_validation` when `raise_on_blocked` is set."
+                )
+            response_validation = raise_on_blocked
+        super().__init__(
+            model=model,
+            history=history,
+            response_validation=response_validation,
+        )
+
+
 class ResponseBlockedError(Exception):
     def __init__(
         self,
@@ -1008,6 +1067,10 @@ def __init__(
         self.responses = responses
 
 
+class ResponseValidationError(ResponseBlockedError):
+    pass
+
+
 ### Structures
 
 

vertexai/preview/generative_models.py

@@ -19,10 +19,10 @@
 from vertexai.generative_models._generative_models import (
     grounding,
     _PreviewGenerativeModel,
+    _PreviewChatSession,
     GenerationConfig,
     GenerationResponse,
     Candidate,
-    ChatSession,
     Content,
     FinishReason,
     FunctionDeclaration,
@@ -31,6 +31,7 @@
     Image,
     Part,
     ResponseBlockedError,
+    ResponseValidationError,
     Tool,
 )
 
@@ -39,6 +40,10 @@ class GenerativeModel(_PreviewGenerativeModel):
     __doc__ = _PreviewGenerativeModel.__doc__
 
 
+class ChatSession(_PreviewChatSession):
+    __doc__ = _PreviewChatSession.__doc__
+
+
 __all__ = [
     "grounding",
     "GenerationConfig",
@@ -54,5 +59,6 @@ class GenerativeModel(_PreviewGenerativeModel):
     "Image",
     "Part",
     "ResponseBlockedError",
+    "ResponseValidationError",
     "Tool",
 ]