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from tempfile import NamedTemporaryFile
from typing import List
import chainlit as cl
from chainlit.types import AskFileResponse
from langchain.chat_models import ChatOpenAI
from langchain.prompts import ChatPromptTemplate
from langchain.schema import Document, StrOutputParser
from langchain.chains import LLMChain
from langchain.document_loaders import PDFPlumberLoader
from langchain.text_splitter import RecursiveCharacterTextSplitter
def process_file(*, file: AskFileResponse) -> List[Document]:
"""Processes one PDF file from a Chainlit AskFileResponse object by first
loading the PDF document and then chunk it into sub documents. Only
supports PDF files.
Args:
file (AskFileResponse): input file to be processed
Raises:
ValueError: when we fail to process PDF files. We consider PDF file
processing failure when there's no text returned. For example, PDFs
with only image contents, corrupted PDFs, etc.
Returns:
List[Document]: List of Document(s). Each individual document has two
fields: page_content(string) and metadata(dict).
"""
# We only support PDF as input.
if file.type != "application/pdf":
raise TypeError("Only PDF files are supported")
with NamedTemporaryFile() as tempfile:
tempfile.write(file.content)
######################################################################
# Exercise 1a:
# We have the input PDF file saved as a temporary file. The name of
# the file is 'tempfile.name'. Please use one of the PDF loaders in
# Langchain to load the file.
######################################################################
loader = PDFPlumberLoader(tempfile.name)
documents = loader.load()
######################################################################
######################################################################
# Exercise 1b:
# We can now chunk the documents now it is loaded. Langchain provides
# a list of helpful text splitters. Please use one of the splitters
# to chunk the file.
######################################################################
text_splitter = RecursiveCharacterTextSplitter(
chunk_size=3000,
chunk_overlap=100
)
docs = text_splitter.split_documents(documents)
######################################################################
# We are adding source_id into the metadata here to denote which
# source document it is.
for i, doc in enumerate(docs):
doc.metadata["source"] = f"source_{i}"
if not docs:
raise ValueError("PDF file parsing failed.")
return docs
@cl.on_chat_start
async def on_chat_start():
######################################################################
# Exercise 1c:
# At the start of our Chat with PDF app, we will first ask users to
# upload the PDF file they want to ask questions against.
#
# Please use Chainlit's AskFileMessage and get the file from users.
# Note for this course, we only want to deal with one single file.
######################################################################
files = None
while files is None:
files = await cl.AskFileMessage(
content="Please Upload the PDF file you want to chat with...",
accept=["application/pdf"],
max_size_mb=20,
).send()
file = files[0]
# Send message to user to let them know we are processing the file
msg = cl.Message(content=f"Processing `{file.name}`...")
await msg.send()
######################################################################
model = ChatOpenAI(
model="gpt-3.5-turbo-16k-0613",
streaming=True
)
prompt = ChatPromptTemplate.from_messages(
[
(
"system",
"You are Chainlit GPT, a helpful assistant.",
),
(
"human",
"{question}"
),
]
)
chain = LLMChain(llm=model, prompt=prompt, output_parser=StrOutputParser())
# We are saving the chain in user_session, so we do not have to rebuild
# it every single time.
cl.user_session.set("chain", chain)
@cl.on_message
async def main(message: cl.Message):
# Let's load the chain from user_session
chain = cl.user_session.get("chain") # type: LLMChain
response = await chain.arun(
question=message.content, callbacks=[cl.LangchainCallbackHandler()]
)
await cl.Message(content=response).send()
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