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import PyPDF2
from langchain_community.embeddings import OllamaEmbeddings
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain_community.vectorstores import Chroma
from langchain.chains import ConversationalRetrievalChain
from langchain_community.chat_models import ChatOllama
from langchain.memory import ChatMessageHistory, ConversationBufferMemory
import chainlit as cl
@cl.on_chat_start
async def on_chat_start():
files = None #Initialize variable to store uploaded files
# Wait for the user to upload a file
while files is None:
files = await cl.AskFileMessage(
content="Please upload a pdf file to begin!",
accept=["application/pdf"],
max_size_mb=100,# Optionally limit the file size
timeout=180, # Set a timeout for user response,
).send()
file = files[0] # Get the first uploaded file
print(file) # Print the file object for debugging
# Sending an image with the local file path
elements = [
cl.Image(name="image", display="inline", path="pic.jpg")
]
# Inform the user that processing has started
msg = cl.Message(content=f"Processing `{file.name}`...",elements=elements)
await msg.send()
# Read the PDF file
pdf = PyPDF2.PdfReader(file.path)
pdf_text = ""
for page in pdf.pages:
pdf_text += page.extract_text()
# Split the text into chunks
text_splitter = RecursiveCharacterTextSplitter(chunk_size=1200, chunk_overlap=50)
texts = text_splitter.split_text(pdf_text)
# Create a metadata for each chunk
metadatas = [{"source": f"{i}-pl"} for i in range(len(texts))]
# Create a Chroma vector store
embeddings = OllamaEmbeddings(model="nomic-embed-text")
docsearch = await cl.make_async(Chroma.from_texts)(
texts, embeddings, metadatas=metadatas
)
# Initialize message history for conversation
message_history = ChatMessageHistory()
# Memory for conversational context
memory = ConversationBufferMemory(
memory_key="chat_history",
output_key="answer",
chat_memory=message_history,
return_messages=True,
)
# Create a chain that uses the Chroma vector store
chain = ConversationalRetrievalChain.from_llm(
ChatOllama(model="gemma:7b"),
chain_type="stuff",
retriever=docsearch.as_retriever(),
memory=memory,
return_source_documents=True,
)
# Let the user know that the system is ready
msg.content = f"Processing `{file.name}` done. You can now ask questions!"
await msg.update()
#store the chain in user session
cl.user_session.set("chain", chain)
@cl.on_message
async def main(message: cl.Message):
# Retrieve the chain from user session
chain = cl.user_session.get("chain")
#call backs happens asynchronously/parallel
cb = cl.AsyncLangchainCallbackHandler()
# call the chain with user's message content
res = await chain.ainvoke(message.content, callbacks=[cb])
answer = res["answer"]
source_documents = res["source_documents"]
text_elements = [] # Initialize list to store text elements
# Process source documents if available
if source_documents:
for source_idx, source_doc in enumerate(source_documents):
source_name = f"source_{source_idx}"
# Create the text element referenced in the message
text_elements.append(
cl.Text(content=source_doc.page_content, name=source_name)
)
source_names = [text_el.name for text_el in text_elements]
# Add source references to the answer
if source_names:
answer += f"\nSources: {', '.join(source_names)}"
else:
answer += "\nNo sources found"
#return results
await cl.Message(content=answer, elements=text_elements).send() |