Update app.py

app.py

@@ -19,7 +19,9 @@ sys.path.append('../..')
 #langchain
 from langchain.text_splitter import RecursiveCharacterTextSplitter, CharacterTextSplitter
 from langchain.embeddings import HuggingFaceEmbeddings
+from langchain.prompts import PromptTemplate
 from langchain.chains import RetrievalQA
+from langchain.prompts import ChatPromptTemplate
 from langchain.schema import StrOutputParser
 from langchain.schema.runnable import Runnable
 from langchain.schema.runnable.config import RunnableConfig
@@ -28,13 +30,16 @@ from langchain.chains import (
 from langchain.vectorstores import Chroma
 from langchain.memory import ConversationBufferMemory
 from langchain.chains import LLMChain
+from langchain.prompts.prompt import PromptTemplate
 from langchain.prompts.chat import ChatPromptTemplate, SystemMessagePromptTemplate
-from langchain.prompts import SystemMessagePromptTemplate, HumanMessagePromptTemplate, ChatPromptTemplate
+from langchain.prompts import SystemMessagePromptTemplate, HumanMessagePromptTemplate, ChatPromptTemplate,  MessagesPlaceholder
 from langchain.document_loaders import PyPDFDirectoryLoader
 from pydantic import BaseModel, Field
 from langchain.output_parsers import PydanticOutputParser
 from langchain_community.llms import HuggingFaceHub
 from langchain_community.document_loaders import WebBaseLoader
+
+from pydantic import BaseModel
 import shutil