2025.10.28

04_langchain_basics/05_practice.py

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+import os
+from dotenv import load_dotenv
+
+load_dotenv()
+
+def create_client():
+    api_key = os.getenv("OPENAI_API_KEY")
+    return api_key
+
+
+from langchain_core.prompts import ChatPromptTemplate,MessagesPlaceholder
+from langchain_openai import ChatOpenAI
+from langchain_core.output_parsers import StrOutputParser
+from langchain_community.chat_message_histories import ChatMessageHistory
+from langchain_core.runnables import RunnableWithMessageHistory
+
+
+def create_bot(llm,sys_prompt):
+    """
+    :param sys_prompt: 系统提示词
+    :param llm: 已配置好的语言模型实例
+    :return:
+    """
+    prompt = ChatPromptTemplate.from_messages([
+        ("system",sys_prompt),
+        MessagesPlaceholder(variable_name="history"),
+        ("human","{input}")
+    ])
+    parser = StrOutputParser()
+    chain = prompt | llm | parser
+    store = {}
+
+    def get_session_history(session_id):
+        return store.setdefault(session_id,ChatMessageHistory())
+
+    return RunnableWithMessageHistory(
+        runnable=chain,
+        get_session_history=get_session_history,
+        input_messages_key="input",
+        history_messages_key="history"
+    )
+
+def main():
+    # 此处集中配置LLM
+    llm = ChatOpenAI(
+        model="deepseek-chat",
+        api_key=create_client(),
+        base_url="https://api.deepseek.com"
+    )
+    prompt = """你是‘小智’，一位专业、耐心且记忆力出色的 AI 助手。
+    你善于倾听，能记住用户之前提到的信息，并在后续对话中自然提及。
+    回答时简洁明了，避免冗余。"""
+    bot = create_bot(llm,prompt)
+    session_id = '123'
+    while 1:
+        user_input = input('\n你:')
+        if user_input == "quit":
+            print('拜拜')
+            break
+        response = bot.invoke({"input":user_input},config={"configurable":{"session_id":session_id}})
+        print("AI:",response)
+
+
+if __name__ == '__main__':
+    main()