Source code for langchain.output_parsers.retry

from __future__ import annotations

from typing import Any, TypeVar

from langchain_core.exceptions import OutputParserException
from langchain_core.language_models import BaseLanguageModel
from langchain_core.output_parsers import BaseOutputParser
from langchain_core.prompt_values import PromptValue
from langchain_core.prompts import BasePromptTemplate, PromptTemplate

NAIVE_COMPLETION_RETRY = """Prompt:
{prompt}
Completion:
{completion}

Above, the Completion did not satisfy the constraints given in the Prompt.
Please try again:"""

NAIVE_COMPLETION_RETRY_WITH_ERROR = """Prompt:
{prompt}
Completion:
{completion}

Above, the Completion did not satisfy the constraints given in the Prompt.
Details: {error}
Please try again:"""

NAIVE_RETRY_PROMPT = PromptTemplate.from_template(NAIVE_COMPLETION_RETRY)
NAIVE_RETRY_WITH_ERROR_PROMPT = PromptTemplate.from_template(
    NAIVE_COMPLETION_RETRY_WITH_ERROR
)

T = TypeVar("T")


[docs]class RetryOutputParser(BaseOutputParser[T]): """Wrap a parser and try to fix parsing errors. Does this by passing the original prompt and the completion to another LLM, and telling it the completion did not satisfy criteria in the prompt. """ parser: BaseOutputParser[T] """The parser to use to parse the output.""" # Should be an LLMChain but we want to avoid top-level imports from langchain.chains retry_chain: Any """The LLMChain to use to retry the completion.""" max_retries: int = 1 """The maximum number of times to retry the parse."""
[docs] @classmethod def from_llm( cls, llm: BaseLanguageModel, parser: BaseOutputParser[T], prompt: BasePromptTemplate = NAIVE_RETRY_PROMPT, max_retries: int = 1, ) -> RetryOutputParser[T]: """Create an RetryOutputParser from a language model and a parser. Args: llm: llm to use for fixing parser: parser to use for parsing prompt: prompt to use for fixing max_retries: Maximum number of retries to parse. Returns: RetryOutputParser """ from langchain.chains.llm import LLMChain chain = LLMChain(llm=llm, prompt=prompt) return cls(parser=parser, retry_chain=chain, max_retries=max_retries)
[docs] def parse_with_prompt(self, completion: str, prompt_value: PromptValue) -> T: """Parse the output of an LLM call using a wrapped parser. Args: completion: The chain completion to parse. prompt_value: The prompt to use to parse the completion. Returns: The parsed completion. """ retries = 0 while retries <= self.max_retries: try: return self.parser.parse(completion) except OutputParserException as e: if retries == self.max_retries: raise e else: retries += 1 completion = self.retry_chain.run( prompt=prompt_value.to_string(), completion=completion ) raise OutputParserException("Failed to parse")
[docs] async def aparse_with_prompt(self, completion: str, prompt_value: PromptValue) -> T: """Parse the output of an LLM call using a wrapped parser. Args: completion: The chain completion to parse. prompt_value: The prompt to use to parse the completion. Returns: The parsed completion. """ retries = 0 while retries <= self.max_retries: try: return await self.parser.aparse(completion) except OutputParserException as e: if retries == self.max_retries: raise e else: retries += 1 completion = await self.retry_chain.arun( prompt=prompt_value.to_string(), completion=completion ) raise OutputParserException("Failed to parse")
[docs] def parse(self, completion: str) -> T: raise NotImplementedError( "This OutputParser can only be called by the `parse_with_prompt` method." )
[docs] def get_format_instructions(self) -> str: return self.parser.get_format_instructions()
@property def _type(self) -> str: return "retry"
[docs]class RetryWithErrorOutputParser(BaseOutputParser[T]): """Wrap a parser and try to fix parsing errors. Does this by passing the original prompt, the completion, AND the error that was raised to another language model and telling it that the completion did not work, and raised the given error. Differs from RetryOutputParser in that this implementation provides the error that was raised back to the LLM, which in theory should give it more information on how to fix it. """ parser: BaseOutputParser[T] """The parser to use to parse the output.""" # Should be an LLMChain but we want to avoid top-level imports from langchain.chains retry_chain: Any """The LLMChain to use to retry the completion.""" max_retries: int = 1 """The maximum number of times to retry the parse."""
[docs] @classmethod def from_llm( cls, llm: BaseLanguageModel, parser: BaseOutputParser[T], prompt: BasePromptTemplate = NAIVE_RETRY_WITH_ERROR_PROMPT, max_retries: int = 1, ) -> RetryWithErrorOutputParser[T]: """Create a RetryWithErrorOutputParser from an LLM. Args: llm: The LLM to use to retry the completion. parser: The parser to use to parse the output. prompt: The prompt to use to retry the completion. max_retries: The maximum number of times to retry the completion. Returns: A RetryWithErrorOutputParser. """ from langchain.chains.llm import LLMChain chain = LLMChain(llm=llm, prompt=prompt) return cls(parser=parser, retry_chain=chain, max_retries=max_retries)
[docs] def parse_with_prompt(self, completion: str, prompt_value: PromptValue) -> T: retries = 0 while retries <= self.max_retries: try: return self.parser.parse(completion) except OutputParserException as e: if retries == self.max_retries: raise e else: retries += 1 completion = self.retry_chain.run( prompt=prompt_value.to_string(), completion=completion, error=repr(e), ) raise OutputParserException("Failed to parse")
[docs] async def aparse_with_prompt(self, completion: str, prompt_value: PromptValue) -> T: retries = 0 while retries <= self.max_retries: try: return await self.parser.aparse(completion) except OutputParserException as e: if retries == self.max_retries: raise e else: retries += 1 completion = await self.retry_chain.arun( prompt=prompt_value.to_string(), completion=completion, error=repr(e), ) raise OutputParserException("Failed to parse")
[docs] def parse(self, completion: str) -> T: raise NotImplementedError( "This OutputParser can only be called by the `parse_with_prompt` method." )
[docs] def get_format_instructions(self) -> str: return self.parser.get_format_instructions()
@property def _type(self) -> str: return "retry_with_error"