【基于langchain + streamlit 完整的与文档对话RAG】

本地部署文档问答webdemo

• 支持 pdf
• 支持 txt
• 支持 doc/docx
• 支持 源文档索引

你的点赞和收藏是我持续分享优质内容的动力哦~

废话不多说直接看效果

准备

• 首先创建一个新环境（选择性）

conda create -n chatwithdocs python=3.11
conda activate chatwithdocs

• 新建一个requirements.txt文件

streamlit
python-docx
PyPDF2
faiss-gpu
langchain
langchain-core
langchain-community

• 然后安装相应的包

pip install -r requirements.txt -U

代码

创建一个app.py 文件， 把下边的复制进去

注意：替换你自己的api-key 和base-url

import streamlit as st
from langchain.text_splitter import RecursiveCharacterTextSplitter
from langchain_community.vectorstores import FAISS
from langchain_openai import ChatOpenAI
from langchain_openai import OpenAIEmbeddings
from langchain_core.documents import Document
from langchain.chains import ConversationalRetrievalChain
import docx
from PyPDF2 import PdfReader

import os
os.environ['OPENAI_API_KEY']='xxx'
# os.environ['OPENAI_BASE_URL']='xxx' # 看你的情况

st.set_page_config(page_title="Chat with Documents", page_icon=":robot:", layout="wide")

st.markdown(
    """<style>
.chat-message {
    padding: 1.5rem; border-radius: 0.5rem; margin-bottom: 1rem; display: flex
}
.chat-message.user {
    background-color: #2b313e
}
.chat-message.bot {
    background-color: #475063
}
.chat-message .avatar {
  width: 20%;
}
.chat-message .avatar img {
  max-width: 78px;
  max-height: 78px;
  border-radius: 50%;
  object-fit: cover;
}
.chat-message .message {
  width: 80%;
  padding: 0 1.5rem;
  color: #fff;
}
.stDeployButton {
            visibility: hidden;
        }
#MainMenu {visibility: hidden;}
footer {visibility: hidden;}

.block-container {
    padding: 2rem 4rem 2rem 4rem;
}

.st-emotion-cache-16txtl3 {
    padding: 3rem 1.5rem;
}
</style>
# """,
    unsafe_allow_html=True,
)

bot_template = """
<div class="chat-message bot">
    <div class="avatar">
        <img src="https://cdn.icon-icons.com/icons2/1371/PNG/512/robot02_90810.png" style="max-height: 78px; max-width: 78px; border-radius: 50%; object-fit: cover;">
    </div>
    <div class="message">{{MSG}}</div>
</div>
"""

user_template = """
<div class="chat-message user">
    <div class="avatar">
        <img src="https://www.shareicon.net/data/512x512/2015/09/18/103160_man_512x512.png" >
    </div>    
    <div class="message">{{MSG}}</div>
</div>
"""


def get_pdf_text(pdf_docs):

    docs = []
    for document in pdf_docs:
        if document.type == "application/pdf":
            pdf_reader = PdfReader(document)
            for idx, page in enumerate(pdf_reader.pages):
                docs.append(
                    Document(
                        page_content=page.extract_text(),
                        metadata={"source": f"{document.name} on page {idx}"},
                    )
                )
        elif (
            document.type
            == "application/vnd.openxmlformats-officedocument.wordprocessingml.document"
        ):
            doc = docx.Document(document)
            for idx, paragraph in enumerate(doc.paragraphs):
                docs.append(
                    Document(
                        page_content=paragraph.text,
                        metadata={"source": f"{document.name} in paragraph {idx}"},
                    )
                )
        elif document.type == "text/plain":
            text = document.getvalue().decode("utf-8")
            docs.append(Document(page_content=text, metadata={"source": document.name}))

    return docs


def get_text_chunks(docs):
    text_splitter = RecursiveCharacterTextSplitter(chunk_size=512, chunk_overlap=0)

    docs_chunks = text_splitter.split_documents(docs)
    return docs_chunks


def get_vectorstore(docs_chunks):
    embeddings = OpenAIEmbeddings()
    vectorstore = FAISS.from_documents(docs_chunks, embedding=embeddings)
    return vectorstore


def get_conversation_chain(vectorstore):
    llm = ChatOpenAI()
    conversation_chain = ConversationalRetrievalChain.from_llm(
        llm=llm,
        retriever=vectorstore.as_retriever(),
        return_source_documents=True,
    )
    return conversation_chain


def handle_userinput_pdf(user_question):
    chat_history = st.session_state.chat_history
    response = st.session_state.conversation(
        {"question": user_question, "chat_history": chat_history}
    )
    st.session_state.chat_history.append(("user", user_question))
    st.session_state.chat_history.append(("assistant", response["answer"]))

    st.write(
        user_template.replace("{{MSG}}", user_question),
        unsafe_allow_html=True,
    )

    sources = response["source_documents"]
    source_names = set([i.metadata["source"] for i in sources])
    src = "\n\n".join(source_names)
    src = f"\n\n> source : {src}"
    message = st.session_state.chat_history[-1]
    st.write(bot_template.replace("{{MSG}}", message[1] + src), unsafe_allow_html=True)


def show_history():
    chat_history = st.session_state.chat_history

    for i, message in enumerate(chat_history):
        if i % 2 == 0:
            st.write(
                user_template.replace("{{MSG}}", message[1]),
                unsafe_allow_html=True,
            )
        else:
            st.write(
                bot_template.replace("{{MSG}}", message[1]), unsafe_allow_html=True
            )


def main():
    st.header("Chat with Documents")

    # 初始化会话状态
    if "conversation" not in st.session_state:
        st.session_state.conversation = None
    if "chat_history" not in st.session_state:
        st.session_state.chat_history = []

    with st.sidebar:
        st.title("文档管理")
        pdf_docs = st.file_uploader(
            "选择文件",
            type=["pdf", "txt", "doc", "docx"],
            accept_multiple_files=True,
        )
        if st.button(
            "处理文档",
            on_click=lambda: setattr(st.session_state, "last_action", "pdf"),
            use_container_width=True,
        ):
            if pdf_docs:
                with st.spinner("Processing"):
                    docs = get_pdf_text(pdf_docs)
                    docs_chunks = get_text_chunks(docs)
                    vectorstore = get_vectorstore(docs_chunks)
                    st.session_state.conversation = get_conversation_chain(vectorstore)
            else:
                st.warning("记得上传文件哦~~")

        def clear_history():
            st.session_state.chat_history = []

        if st.session_state.chat_history:
            st.button("清空对话", on_click=clear_history, use_container_width=True)

    with st.container():
        user_question = st.chat_input("输入点什么~")

    with st.container(height=400):
        show_history()
        if user_question:
            if st.session_state.conversation is not None:
                handle_userinput_pdf(user_question)
            else:
                st.warning("记得上传文件哦~~")


if __name__ == "__main__":
    main()

启动

• 自动在浏览器打开

streamlit run app.py