Source code for langchain.chains.graph_qa.gremlin

"""Question answering over a graph."""
from __future__ import annotations

from typing import Any, Dict, List, Optional

from langchain_community.graphs import GremlinGraph
from langchain_core.callbacks.manager import CallbackManager, CallbackManagerForChainRun
from langchain_core.language_models import BaseLanguageModel
from langchain_core.prompts import BasePromptTemplate
from langchain_core.prompts.prompt import PromptTemplate
from langchain_core.pydantic_v1 import Field

from langchain.chains.base import Chain
from langchain.chains.graph_qa.prompts import (
    CYPHER_QA_PROMPT,
    GRAPHDB_SPARQL_FIX_TEMPLATE,
    GREMLIN_GENERATION_PROMPT,
)
from langchain.chains.llm import LLMChain

INTERMEDIATE_STEPS_KEY = "intermediate_steps"


[docs]def extract_gremlin(text: str) -> str: """Extract Gremlin code from a text. Args: text: Text to extract Gremlin code from. Returns: Gremlin code extracted from the text. """ text = text.replace("`", "") if text.startswith("gremlin"): text = text[len("gremlin") :] return text.replace("\n", "")
[docs]class GremlinQAChain(Chain): """Chain for question-answering against a graph by generating gremlin statements. *Security note*: Make sure that the database connection uses credentials that are narrowly-scoped to only include necessary permissions. Failure to do so may result in data corruption or loss, since the calling code may attempt commands that would result in deletion, mutation of data if appropriately prompted or reading sensitive data if such data is present in the database. The best way to guard against such negative outcomes is to (as appropriate) limit the permissions granted to the credentials used with this tool. See https://python.langchain.com/docs/security for more information. """ graph: GremlinGraph = Field(exclude=True) gremlin_generation_chain: LLMChain qa_chain: LLMChain gremlin_fix_chain: LLMChain max_fix_retries: int = 3 input_key: str = "query" #: :meta private: output_key: str = "result" #: :meta private: top_k: int = 100 return_direct: bool = False return_intermediate_steps: bool = False @property def input_keys(self) -> List[str]: """Input keys. :meta private: """ return [self.input_key] @property def output_keys(self) -> List[str]: """Output keys. :meta private: """ _output_keys = [self.output_key] return _output_keys
[docs] @classmethod def from_llm( cls, llm: BaseLanguageModel, *, gremlin_fix_prompt: BasePromptTemplate = PromptTemplate( input_variables=["error_message", "generated_sparql", "schema"], template=GRAPHDB_SPARQL_FIX_TEMPLATE.replace("SPARQL", "Gremlin").replace( "in Turtle format", "" ), ), qa_prompt: BasePromptTemplate = CYPHER_QA_PROMPT, gremlin_prompt: BasePromptTemplate = GREMLIN_GENERATION_PROMPT, **kwargs: Any, ) -> GremlinQAChain: """Initialize from LLM.""" qa_chain = LLMChain(llm=llm, prompt=qa_prompt) gremlin_generation_chain = LLMChain(llm=llm, prompt=gremlin_prompt) gremlinl_fix_chain = LLMChain(llm=llm, prompt=gremlin_fix_prompt) return cls( qa_chain=qa_chain, gremlin_generation_chain=gremlin_generation_chain, gremlin_fix_chain=gremlinl_fix_chain, **kwargs, )
def _call( self, inputs: Dict[str, Any], run_manager: Optional[CallbackManagerForChainRun] = None, ) -> Dict[str, str]: """Generate gremlin statement, use it to look up in db and answer question.""" _run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager() callbacks = _run_manager.get_child() question = inputs[self.input_key] intermediate_steps: List = [] chain_response = self.gremlin_generation_chain.invoke( {"question": question, "schema": self.graph.get_schema}, callbacks=callbacks ) generated_gremlin = extract_gremlin( chain_response[self.gremlin_generation_chain.output_key] ) _run_manager.on_text("Generated gremlin:", end="\n", verbose=self.verbose) _run_manager.on_text( generated_gremlin, color="green", end="\n", verbose=self.verbose ) intermediate_steps.append({"query": generated_gremlin}) if generated_gremlin: context = self.execute_with_retry( _run_manager, callbacks, generated_gremlin )[: self.top_k] else: context = [] if self.return_direct: final_result = context else: _run_manager.on_text("Full Context:", end="\n", verbose=self.verbose) _run_manager.on_text( str(context), color="green", end="\n", verbose=self.verbose ) intermediate_steps.append({"context": context}) result = self.qa_chain.invoke( {"question": question, "context": context}, callbacks=callbacks, ) final_result = result[self.qa_chain.output_key] chain_result: Dict[str, Any] = {self.output_key: final_result} if self.return_intermediate_steps: chain_result[INTERMEDIATE_STEPS_KEY] = intermediate_steps return chain_result
[docs] def execute_query(self, query: str) -> List[Any]: try: return self.graph.query(query) except Exception as e: if hasattr(e, "status_message"): raise ValueError(e.status_message) else: raise ValueError(str(e))
[docs] def execute_with_retry( self, _run_manager: CallbackManagerForChainRun, callbacks: CallbackManager, generated_gremlin: str, ) -> List[Any]: try: return self.execute_query(generated_gremlin) except Exception as e: retries = 0 error_message = str(e) self.log_invalid_query(_run_manager, generated_gremlin, error_message) while retries < self.max_fix_retries: try: fix_chain_result = self.gremlin_fix_chain.invoke( { "error_message": error_message, # we are borrowing template from sparql "generated_sparql": generated_gremlin, "schema": self.schema, }, callbacks=callbacks, ) fixed_gremlin = fix_chain_result[self.gremlin_fix_chain.output_key] return self.execute_query(fixed_gremlin) except Exception as e: retries += 1 parse_exception = str(e) self.log_invalid_query(_run_manager, fixed_gremlin, parse_exception) raise ValueError("The generated Gremlin query is invalid.")
[docs] def log_invalid_query( self, _run_manager: CallbackManagerForChainRun, generated_query: str, error_message: str, ) -> None: _run_manager.on_text("Invalid Gremlin query: ", end="\n", verbose=self.verbose) _run_manager.on_text( generated_query, color="red", end="\n", verbose=self.verbose ) _run_manager.on_text( "Gremlin Query Parse Error: ", end="\n", verbose=self.verbose ) _run_manager.on_text( error_message, color="red", end="\n\n", verbose=self.verbose )