add input type for convo retrieval chain (#11679)

libs/langchain/langchain/chains/conversational_retrieval/base.py

@@ -5,7 +5,7 @@ import inspect
 import warnings
 from abc import abstractmethod
 from pathlib import Path
-from typing import Any, Callable, Dict, List, Optional, Tuple, Union
+from typing import Any, Callable, Dict, List, Optional, Tuple, Type, Union
 
 from langchain.callbacks.manager import (
     AsyncCallbackManagerForChainRun,
@@ -18,7 +18,7 @@ from langchain.chains.combine_documents.stuff import StuffDocumentsChain
 from langchain.chains.conversational_retrieval.prompts import CONDENSE_QUESTION_PROMPT
 from langchain.chains.llm import LLMChain
 from langchain.chains.question_answering import load_qa_chain
-from langchain.pydantic_v1 import Extra, Field, root_validator
+from langchain.pydantic_v1 import BaseModel, Extra, Field, root_validator
 from langchain.schema import BasePromptTemplate, BaseRetriever, Document
 from langchain.schema.language_model import BaseLanguageModel
 from langchain.schema.messages import BaseMessage
@@ -50,6 +50,11 @@ def _get_chat_history(chat_history: List[CHAT_TURN_TYPE]) -> str:
     return buffer
 
 
+class InputType(BaseModel):
+    question: str
+    chat_history: List[CHAT_TURN_TYPE]
+
+
 class BaseConversationalRetrievalChain(Chain):
     """Chain for chatting with an index."""
 
@@ -87,6 +92,10 @@ class BaseConversationalRetrievalChain(Chain):
         """Input keys."""
         return ["question", "chat_history"]
 
+    @property
+    def input_schema(self) -> Type[BaseModel]:
+        return InputType
+
     @property
     def output_keys(self) -> List[str]:
         """Return the output keys.