OutputParserException Class — langchain Architecture

Architecture documentation for the OutputParserException class in exceptions.py from the langchain codebase.

Class python

Entity Profile

Dependency Diagram

graph TD
  0dd75536_e009_da4d_0090_3d46069fce40["OutputParserException"]
  75598d2c_67b6_82ee_9927_fe755991e82f["LangChainException"]
  0dd75536_e009_da4d_0090_3d46069fce40 -->|extends| 75598d2c_67b6_82ee_9927_fe755991e82f
  445b6774_2020_8a8c_b7c7_f5804c232169["exceptions.py"]
  0dd75536_e009_da4d_0090_3d46069fce40 -->|defined in| 445b6774_2020_8a8c_b7c7_f5804c232169
  fce3a01a_3f42_aea4_cfc7_64f82c3763a2["__init__()"]
  0dd75536_e009_da4d_0090_3d46069fce40 -->|method| fce3a01a_3f42_aea4_cfc7_64f82c3763a2

Relationship Graph

Source Code

libs/core/langchain_core/exceptions.py lines 15–65

class OutputParserException(ValueError, LangChainException):  # noqa: N818
    """Exception that output parsers should raise to signify a parsing error.

    This exists to differentiate parsing errors from other code or execution errors
    that also may arise inside the output parser.

    `OutputParserException` will be available to catch and handle in ways to fix the
    parsing error, while other errors will be raised.
    """

    def __init__(
        self,
        error: Any,
        observation: str | None = None,
        llm_output: str | None = None,
        send_to_llm: bool = False,  # noqa: FBT001,FBT002
    ):
        """Create an `OutputParserException`.

        Args:
            error: The error that's being re-raised or an error message.
            observation: String explanation of error which can be passed to a model to
                try and remediate the issue.
            llm_output: String model output which is error-ing.

            send_to_llm: Whether to send the observation and llm_output back to an Agent
                after an `OutputParserException` has been raised.

                This gives the underlying model driving the agent the context that the
                previous output was improperly structured, in the hopes that it will
                update the output to the correct format.

        Raises:
            ValueError: If `send_to_llm` is `True` but either observation or
                `llm_output` are not provided.
        """
        if isinstance(error, str):
            error = create_message(
                message=error, error_code=ErrorCode.OUTPUT_PARSING_FAILURE
            )

        super().__init__(error)
        if send_to_llm and (observation is None or llm_output is None):
            msg = (
                "Arguments 'observation' & 'llm_output'"
                " are required if 'send_to_llm' is True"
            )
            raise ValueError(msg)
        self.observation = observation
        self.llm_output = llm_output
        self.send_to_llm = send_to_llm