From d392e030bead62dd26d37b496221dbe478c3d2ad Mon Sep 17 00:00:00 2001
From: Nuno Campos <nuno@langchain.dev>
Date: Thu, 19 Oct 2023 18:30:05 +0100
Subject: [PATCH] Add default value (#12032)

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---
 .../langchain/langchain/chains/conversational_retrieval/base.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libs/langchain/langchain/chains/conversational_retrieval/base.py b/libs/langchain/langchain/chains/conversational_retrieval/base.py
index 89882ede89c..97528bd8e5d 100644
--- a/libs/langchain/langchain/chains/conversational_retrieval/base.py
+++ b/libs/langchain/langchain/chains/conversational_retrieval/base.py
@@ -52,7 +52,7 @@ def _get_chat_history(chat_history: List[CHAT_TURN_TYPE]) -> str:
 
 class InputType(BaseModel):
     question: str
-    chat_history: List[CHAT_TURN_TYPE]
+    chat_history: List[CHAT_TURN_TYPE] = Field(default_factory=list)
 
 
 class BaseConversationalRetrievalChain(Chain):