pass date_str in chain for system prompt

chain.py

@@ -1,5 +1,6 @@
 import os
 import mlflow
+import datetime
 import streamlit as st
 from operator import itemgetter
 from langchain_huggingface import HuggingFaceEmbeddings
@@ -162,8 +163,8 @@ class ChainBuilder:
         # RAG Chain
         chain = (
             {
-                # set 'question' to the result of: grabbing the ["messages"] component of the dict we 'invoke()' or 'stream()', then passing to extract_user_query_string()
-                "question": itemgetter("messages") | RunnableLambda(self.extract_user_query_string),
+                "date_str": datetime.datetime.now().strftime("%B %d, %Y"), # date to be passed to system prompt for context of when knowledge base was last updated
+                "question": itemgetter("messages") | RunnableLambda(self.extract_user_query_string), # set 'question' to the result of: grabbing the ["messages"] component of the dict we 'invoke()' or 'stream()', then passing to extract_user_query_string()
                 "chat_history": itemgetter("messages") | RunnableLambda(self.extract_chat_history),
                 "formatted_chat_history": itemgetter("messages")
                 | RunnableLambda(self.format_chat_history_for_prompt),