为什么Langchain占位符没有被调用？

Question

我的目标是将

language

占位符插入到调用方法中，但目前响应始终是英语。我遵循本教程 -> https://python.langchain.com/v0.2/docs/tutorials/chatbot/

有什么理由吗？

# Securely input the OpenAI API key
api_key = os.getenv("OPENAI_API_KEY")

# Initialize the ChatOpenAI model with the API key
model = ChatOpenAI(model="gpt-3.5-turbo", api_key=api_key, verbose=True)


def invoke_model(session_id: str, message: str):
    # Define the prompt with ChatPromptTemplate
    prompt = ChatPromptTemplate.from_messages(
        [
            ("system", "You are a helpful assistant. Answer all questions to the best of your ability in {language}."),
            MessagesPlaceholder(variable_name="messages"),
        ]
    )

    # Create the chain using the prompt and the model
    chain = prompt | model

    # Use with_message_history to handle messages
    with_message_history = RunnableWithMessageHistory(chain, get_session_history, input_messages_key="messages")

    human_message = HumanMessage(content=message)
    session_history = get_session_history(session_id)
    session_history.add_message(human_message)  # Add the human message to the history
    config = {"configurable": {"session_id": session_id}}
    response = with_message_history.invoke({"messages": [human_message], "language": "Spanish"}, config=config)
    assistant_message = AIMessage(content=response.content)
    session_history.add_message(assistant_message)  # Add the assistant's response to the history
    return response.content

Answer 1

它不起作用，因为您使用的是

('system', '<your message with placeholder>')

，它相当于硬编码消息（

SystemMessage

类），即它不被视为模板，因此不会为其生成输入变量。为了修复它，您需要将其替换为

prompt = ChatPromptTemplate.from_messages(
        [
            SystemMessageTemplate.from_template("You are a helpful assistant. Answer all questions to the best of your ability in {language}."),
            MessagesPlaceholder(variable_name="messages"),
        ]
    )