2025.10.30

04_langchain_basics/04_memory.py

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+import os
+from dotenv import load_dotenv
+
+
+load_dotenv()
+api_key = os.getenv("OPENAI_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
+
+
+prompt = ChatPromptTemplate.from_messages([
+    ("system", "你非常可爱，说话末尾会带个喵"),
+    MessagesPlaceholder(variable_name="history"),
+    ("human", "{input}")  # {input}:占位符
+])
+llm = ChatOpenAI(
+    model="deepseek-chat",
+    api_key=api_key,
+    base_url="https://api.deepseek.com"
+)
+parser = StrOutputParser()
+
+chain = prompt | llm | parser
+
+# 存储所有会话历史(可用数据库替换)
+# 此处用字典模拟，也可替换成Redis、SQL等
+store = {}
+
+def get_session_history(session_id:str):
+    """根据session_id获取该用户的聊天历史"""
+    if session_id not in store:
+        store[session_id] = ChatMessageHistory() # 创建新的历史记录
+    return store[session_id]
+
+
+# 包装成带记忆的Runnable
+runnable_with_memory = RunnableWithMessageHistory(
+    runnable=chain,
+    get_session_history=get_session_history,
+    input_messages_key="input",
+    history_messages_key="history"
+)
+
+session_id = 'user_123'
+while 1:
+    user_input = input("\n你:")
+    if user_input=="quit":
+        print('拜拜喵!')
+        break
+    response = runnable_with_memory.invoke(
+        {"input":user_input},
+        config={"configurable":{"session_id":session_id}}
+    )
+    print(f'AI:{response}')
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