I m using LangChain to build a NL application. I want the interactions with the LLM to be recorded in a variable I can use for logging and debugging purposes. I have created a very simple chain:
from langchain import PromptTemplate
from langchain.llms import OpenAI
llm = OpenAI()
prompt = PromptTemplate.from_template("1 + {number} = ")
handler = MyCustomHandler()
chain = LLMChain(llm=llm, prompt=prompt, callbacks=[handler])
chain.run(number=2)
To record what s going on, I have created a custom CallbackHandler:
class MyCustomHandler(BaseCallbackHandler):
def on_text(self, text: str, **kwargs: Any) -> Any:
print(f"Text: {text}")
self.log = text
def on_chain_start(
self, serialized: Dict[str, Any], inputs: Dict[str, Any], **kwargs: Any
) -> Any:
"""Run when chain starts running."""
print("Chain started running")
This works more or less as expected, but it has some side effects that I cannot figure out where they are coming from. The output is:
And the handler.log variable contains:
Prompt after formatting:
x1b[32;1mx1b[1;3m1 + 2 = x1b[0m
Where are the "Prompt after formatting" and the ANSI codes setting the text as green coming from? Can I get rid of them?
Overall, is there a better way I m missing to use the callback system to log the application? This seems to be poorly documented.