Index.py

from fastapi import FastAPI
import os


import phoenix as px
from phoenix.trace.langchain import OpenInferenceTracer, LangChainInstrumentor


from langchain.embeddings import HuggingFaceEmbeddings #for using HugginFace models
from langchain.chains.question_answering import load_qa_chain
from langchain import HuggingFaceHub

from langchain.chains import RetrievalQA
from langchain.callbacks import StdOutCallbackHandler

#from langchain.retrievers import KNNRetriever
from langchain.storage import LocalFileStore
from langchain.embeddings import CacheBackedEmbeddings
from langchain.vectorstores import FAISS


from langchain.document_loaders import WebBaseLoader
from langchain.text_splitter import RecursiveCharacterTextSplitter

# from langchain import HuggingFaceHub
# from langchain.prompts import PromptTemplate
# from langchain.chains import LLMChain
# from txtai.embeddings import Embeddings
# from txtai.pipeline import Extractor

# import pandas as pd
# import sqlite3
# import os

# NOTE - we configure docs_url to serve the interactive Docs at the root path
# of the app. This way, we can use the docs as a landing page for the app on Spaces.
app = FastAPI(docs_url="/")

#phoenix setup
session = px.launch_app()
# If no exporter is specified, the tracer will export to the locally running Phoenix server
tracer = OpenInferenceTracer()
# If no tracer is specified, a tracer is constructed for you
LangChainInstrumentor(tracer).instrument()
print(session.url)


os.environ["HUGGINGFACEHUB_API_TOKEN"] = "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"

# embedding cache
store = LocalFileStore("./cache/")

# define embedder
core_embeddings_model  = HuggingFaceEmbeddings(model_name="sentence-transformers/all-mpnet-base-v2")
embedder = CacheBackedEmbeddings.from_bytes_store(core_embeddings_model, store)

# define llm
llm=HuggingFaceHub(repo_id="google/flan-t5-xxl", model_kwargs={"temperature":1, "max_length":1000000})
#llm=HuggingFaceHub(repo_id="gpt2", model_kwargs={"temperature":1, "max_length":1000000})
handler =  StdOutCallbackHandler()

# set global variable
vectorstore
retriever


def initialize_vectorstore():

    webpage_loader = WebBaseLoader("https://www.tredence.com/case-studies/tredence-helped-a-global-retailer-providing-holistic-campaign-analytics-by-using-the-power-of-gcp").load()
    webpage_chunks = text_splitter.transform_documents(webpage_loader)

    # store embeddings in vector store
    vectorstore = FAISS.from_documents(webpage_chunks, embedder)
    print("vector store initialized with sample doc")

    # instantiate a retriever
    retriever = vectorstore.as_retriever()


def _text_splitter(doc):
    text_splitter = RecursiveCharacterTextSplitter(
        chunk_size=500,
        chunk_overlap=50,
        length_function=len,
    )
    return text_splitter.transform_documents(doc)

def _load_docs(path: str):
    load_doc = WebBaseLoader(path).load()
    doc = _text_splitter(load_doc)
    return doc


@app.get("/index/")
def get_domain_file_path(file_path: str):
    print(file_path)
     
    webpage_loader = _load_docs(file_path)

    webpage_chunks = _text_splitter(webpage_loader)

    # store embeddings in vector store
    vectorstore.add_documents(webpage_chunks)

    return "document loaded to vector store successfully!!"


def _prompt(question):
    return f"""Answer following question using only the context below. Say 'Could not find answer with provided context' when question can't be answered.
            Question: {question}
            Context: """


@app.get("/rag")
def rag( question: str):   

    chain = RetrievalQA.from_chain_type(
    llm=llm,
    retriever=retriever,
    callbacks=[handler],
    return_source_documents=True
    )

    #response = chain("how tredence brought good insight?")
    response = chain(_prompt(question))
 
    return {"question": question, "answer": response['result']}


initialize_vectorstore()