第七章、聊天 Chat¶

#import os
#os.environ["LANGCHAIN_TRACING_V2"] = "true"
#os.environ["LANGCHAIN_ENDPOINT"] = "https://api.langchain.plus"
#os.environ["LANGCHAIN_API_KEY"] = "..."

from langchain.memory import ConversationBufferMemory
memory = ConversationBufferMemory(
    memory_key="chat_history", # 与 prompt 的输入变量保持一致。
    return_messages=True # 将以消息列表的形式返回聊天记录，而不是单个字符串
)

from langchain.chains.conversational_retrieval.base import ConversationalRetrievalChain
retriever=vectordb.as_retriever()
qa = ConversationalRetrievalChain.from_llm(
    llm,
    retriever=retriever,
    memory=memory
)

from langchain.embeddings.openai import OpenAIEmbeddings
from langchain.text_splitter import CharacterTextSplitter, RecursiveCharacterTextSplitter
from langchain.vectorstores import DocArrayInMemorySearch
from langchain.document_loaders import TextLoader
from langchain.chains.retrieval_qa.base import RetrievalQA
from langchain.memory import ConversationBufferMemory
from langchain.chat_models.openai import ChatOpenAI
from langchain.document_loaders import TextLoader
from langchain.document_loaders import PyPDFLoader

def load_db(file, chain_type, k):
    """
    该函数用于加载 PDF 文件，切分文档，生成文档的嵌入向量，创建向量数据库，定义检索器，并创建聊天机器人实例。

    参数:
    file (str): 要加载的 PDF 文件路径。
    chain_type (str): 链类型，用于指定聊天机器人的类型。
    k (int): 在检索过程中，返回最相似的 k 个结果。

    返回:
    qa (ConversationalRetrievalChain): 创建的聊天机器人实例。
    """
    # 载入文档
    loader = PyPDFLoader(file)
    documents = loader.load()
    # 切分文档
    text_splitter = RecursiveCharacterTextSplitter(chunk_size=1000, chunk_overlap=150)
    docs = text_splitter.split_documents(documents)
    # 定义 Embeddings
    embeddings = OpenAIEmbeddings(model='text-embedding-3-small')
    # 根据数据创建向量数据库
    db = DocArrayInMemorySearch.from_documents(docs, embeddings)
    # 定义检索器
    retriever = db.as_retriever(search_type="similarity", search_kwargs={"k": k})
    # 创建 chatbot 链，Memory 由外部管理
    qa = ConversationalRetrievalChain.from_llm(
        llm=ChatOpenAI(model_name=llm_name, temperature=0), 
        chain_type=chain_type, 
        retriever=retriever, 
        return_source_documents=True,
        return_generated_question=True,
    )
    return qa 

import panel as pn
import param

# 用于存储聊天记录、回答、数据库查询和回复
class cbfs(param.Parameterized):
    chat_history = param.List([])
    answer = param.String("")
    db_query  = param.String("")
    db_response = param.List([])
    
    def __init__(self,  **params):
        super(cbfs, self).__init__( **params)
        self.panels = []
        self.loaded_file = "docs/cs229_lectures/MachineLearning-Lecture01.pdf"
        self.qa = load_db(self.loaded_file,"stuff", 4)
    
    # 将文档加载到聊天机器人中
    def call_load_db(self, count):
        """
        count: 数量
        """
        if count == 0 or file_input.value is None:  # 初始化或未指定文件 :
            return pn.pane.Markdown(f"Loaded File: {self.loaded_file}")
        else:
            file_input.save("temp.pdf")  # 本地副本
            self.loaded_file = file_input.filename
            button_load.button_style="outline"
            self.qa = load_db("temp.pdf", "stuff", 4)
            button_load.button_style="solid"
        self.clr_history()
        return pn.pane.Markdown(f"Loaded File: {self.loaded_file}")

    # 处理对话链
    def convchain(self, query):
        """
        query: 用户的查询
        """
        if not query:
            return pn.WidgetBox(pn.Row('User:', pn.pane.Markdown("", width=600)), scroll=True)
        result = self.qa({"question": query, "chat_history": self.chat_history})
        self.chat_history.extend([(query, result["answer"])])
        self.db_query = result["generated_question"]
        self.db_response = result["source_documents"]
        self.answer = result['answer'] 
        self.panels.extend([
            pn.Row('User:', pn.pane.Markdown(query, width=600)),
            pn.Row('ChatBot:', pn.pane.Markdown(self.answer, width=600, styles={'background-color': '#F6F6F6'}))
        ])
        inp.value = ''  # 清除时清除装载指示器
        return pn.WidgetBox(*self.panels,scroll=True)
    
    # 获取最后发送到数据库的问题
    @param.depends('db_query ', )
    def get_lquest(self):
        if not self.db_query :
            return pn.Column(
                pn.Row(pn.pane.Markdown(f"Last question to DB:", styles={'background-color': '#F6F6F6'})),
                pn.Row(pn.pane.Str("no DB accesses so far"))
            )
        return pn.Column(
            pn.Row(pn.pane.Markdown(f"DB query:", styles={'background-color': '#F6F6F6'})),
            pn.pane.Str(self.db_query )
        )
    
    # 获取数据库返回的源文件
    @param.depends('db_response', )
    def get_sources(self):
        if not self.db_response:
            return 
        rlist=[pn.Row(pn.pane.Markdown(f"Result of DB lookup:", styles={'background-color': '#F6F6F6'}))]
        for doc in self.db_response:
            rlist.append(pn.Row(pn.pane.Str(doc)))
        return pn.WidgetBox(*rlist, width=600, scroll=True)

    # 获取当前聊天记录
    @param.depends('convchain', 'clr_history') 
    def get_chats(self):
        if not self.chat_history:
            return pn.WidgetBox(pn.Row(pn.pane.Str("No History Yet")), width=600, scroll=True)
        rlist=[pn.Row(pn.pane.Markdown(f"Current Chat History variable", styles={'background-color': '#F6F6F6'}))]
        for exchange in self.chat_history:
            rlist.append(pn.Row(pn.pane.Str(exchange)))
        return pn.WidgetBox(*rlist, width=600, scroll=True)
    
    # 清除聊天记录
    def clr_history(self,count=0):
        self.chat_history = []
        return