From 3c44500af66a22b9772b86cdec82aa007e2213f2 Mon Sep 17 00:00:00 2001
From: Willy Douhard <willy.douhard@gmail.com>
Date: Sun, 26 Nov 2023 14:40:18 +0100
Subject: [PATCH] fix lc placeholder with lcel (#568)

---
 backend/chainlit/langchain/callbacks.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/backend/chainlit/langchain/callbacks.py b/backend/chainlit/langchain/callbacks.py
index bfa3e1f98b..72254e57fe 100644
--- a/backend/chainlit/langchain/callbacks.py
+++ b/backend/chainlit/langchain/callbacks.py
@@ -241,9 +241,12 @@ def build_template_messages() -> List[PromptMessage]:
                 if "placeholder" in class_name.lower():
                     variable_name = lc_message.get(
                         "variable_name"
+                    ) or message_kwargs.get(
+                        "variable_name"
                     )  # type: Optional[str]
                     variable = inputs.get(variable_name, [])
                     placeholder_size = len(variable)
+
                     if placeholder_size:
                         template_messages += [
                             PromptMessage(placeholder_size=placeholder_size)