Source code for langchain_core.callbacks.file

"""Callback Handler that writes to a file."""

from __future__ import annotations

from typing import Any, Dict, Optional, TextIO, cast

from langchain_core.agents import AgentAction, AgentFinish
from langchain_core.callbacks import BaseCallbackHandler
from langchain_core.utils.input import print_text


[docs]class FileCallbackHandler(BaseCallbackHandler): """Callback Handler that writes to a file. Parameters: file: The file to write to. color: The color to use for the text. """
[docs] def __init__( self, filename: str, mode: str = "a", color: Optional[str] = None ) -> None: """Initialize callback handler. Args: filename: The filename to write to. mode: The mode to open the file in. Defaults to "a". color: The color to use for the text. Defaults to None. """ self.file = cast(TextIO, open(filename, mode, encoding="utf-8")) self.color = color
def __del__(self) -> None: """Destructor to cleanup when done.""" self.file.close()
[docs] def on_chain_start( self, serialized: Dict[str, Any], inputs: Dict[str, Any], **kwargs: Any ) -> None: """Print out that we are entering a chain. Args: serialized (Dict[str, Any]): The serialized chain. inputs (Dict[str, Any]): The inputs to the chain. **kwargs (Any): Additional keyword arguments. """ class_name = serialized.get("name", serialized.get("id", ["<unknown>"])[-1]) print_text( f"\n\n\033[1m> Entering new {class_name} chain...\033[0m", end="\n", file=self.file, )
[docs] def on_chain_end(self, outputs: Dict[str, Any], **kwargs: Any) -> None: """Print out that we finished a chain. Args: outputs (Dict[str, Any]): The outputs of the chain. **kwargs (Any): Additional keyword arguments. """ print_text("\n\033[1m> Finished chain.\033[0m", end="\n", file=self.file)
[docs] def on_agent_action( self, action: AgentAction, color: Optional[str] = None, **kwargs: Any ) -> Any: """Run on agent action. Args: action (AgentAction): The agent action. color (Optional[str], optional): The color to use for the text. Defaults to None. **kwargs (Any): Additional keyword arguments. """ print_text(action.log, color=color or self.color, file=self.file)
[docs] def on_tool_end( self, output: str, color: Optional[str] = None, observation_prefix: Optional[str] = None, llm_prefix: Optional[str] = None, **kwargs: Any, ) -> None: """If not the final action, print out observation. Args: output (str): The output to print. color (Optional[str], optional): The color to use for the text. Defaults to None. observation_prefix (Optional[str], optional): The observation prefix. Defaults to None. llm_prefix (Optional[str], optional): The LLM prefix. Defaults to None. **kwargs (Any): Additional keyword arguments. """ if observation_prefix is not None: print_text(f"\n{observation_prefix}", file=self.file) print_text(output, color=color or self.color, file=self.file) if llm_prefix is not None: print_text(f"\n{llm_prefix}", file=self.file)
[docs] def on_text( self, text: str, color: Optional[str] = None, end: str = "", **kwargs: Any ) -> None: """Run when the agent ends. Args: text (str): The text to print. color (Optional[str], optional): The color to use for the text. Defaults to None. end (str, optional): The end character. Defaults to "". **kwargs (Any): Additional keyword arguments. """ print_text(text, color=color or self.color, end=end, file=self.file)
[docs] def on_agent_finish( self, finish: AgentFinish, color: Optional[str] = None, **kwargs: Any ) -> None: """Run on the agent end. Args: finish (AgentFinish): The agent finish. color (Optional[str], optional): The color to use for the text. Defaults to None. **kwargs (Any): Additional keyword arguments. """ print_text(finish.log, color=color or self.color, end="\n", file=self.file)