Source code for langchain.chains.graph_qa.ontotext_graphdb

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

from typing import TYPE_CHECKING, Any, Dict, List, Optional

if TYPE_CHECKING:
    import rdflib

from langchain_community.graphs import OntotextGraphDBGraph
from langchain_core.callbacks.manager import CallbackManager, CallbackManagerForChainRun
from langchain_core.language_models import BaseLanguageModel
from langchain_core.prompts.base import BasePromptTemplate
from langchain_core.pydantic_v1 import Field

from langchain.chains.base import Chain
from langchain.chains.graph_qa.prompts import (
    GRAPHDB_QA_PROMPT,
    GRAPHDB_SPARQL_FIX_PROMPT,
    GRAPHDB_SPARQL_GENERATION_PROMPT,
)
from langchain.chains.llm import LLMChain


[docs]class OntotextGraphDBQAChain(Chain): """Question-answering against Ontotext GraphDB https://graphdb.ontotext.com/ by generating SPARQL queries. *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: OntotextGraphDBGraph = Field(exclude=True) sparql_generation_chain: LLMChain sparql_fix_chain: LLMChain max_fix_retries: int qa_chain: LLMChain input_key: str = "query" #: :meta private: output_key: str = "result" #: :meta private: @property def input_keys(self) -> List[str]: return [self.input_key] @property def output_keys(self) -> List[str]: _output_keys = [self.output_key] return _output_keys
[docs] @classmethod def from_llm( cls, llm: BaseLanguageModel, *, sparql_generation_prompt: BasePromptTemplate = GRAPHDB_SPARQL_GENERATION_PROMPT, sparql_fix_prompt: BasePromptTemplate = GRAPHDB_SPARQL_FIX_PROMPT, max_fix_retries: int = 5, qa_prompt: BasePromptTemplate = GRAPHDB_QA_PROMPT, **kwargs: Any, ) -> OntotextGraphDBQAChain: """Initialize from LLM.""" sparql_generation_chain = LLMChain(llm=llm, prompt=sparql_generation_prompt) sparql_fix_chain = LLMChain(llm=llm, prompt=sparql_fix_prompt) max_fix_retries = max_fix_retries qa_chain = LLMChain(llm=llm, prompt=qa_prompt) return cls( qa_chain=qa_chain, sparql_generation_chain=sparql_generation_chain, sparql_fix_chain=sparql_fix_chain, max_fix_retries=max_fix_retries, **kwargs, )
def _call( self, inputs: Dict[str, Any], run_manager: Optional[CallbackManagerForChainRun] = None, ) -> Dict[str, str]: """ Generate a SPARQL query, use it to retrieve a response from GraphDB and answer the question. """ _run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager() callbacks = _run_manager.get_child() prompt = inputs[self.input_key] ontology_schema = self.graph.get_schema sparql_generation_chain_result = self.sparql_generation_chain.invoke( {"prompt": prompt, "schema": ontology_schema}, callbacks=callbacks ) generated_sparql = sparql_generation_chain_result[ self.sparql_generation_chain.output_key ] generated_sparql = self._get_prepared_sparql_query( _run_manager, callbacks, generated_sparql, ontology_schema ) query_results = self._execute_query(generated_sparql) qa_chain_result = self.qa_chain.invoke( {"prompt": prompt, "context": query_results}, callbacks=callbacks ) result = qa_chain_result[self.qa_chain.output_key] return {self.output_key: result} def _get_prepared_sparql_query( self, _run_manager: CallbackManagerForChainRun, callbacks: CallbackManager, generated_sparql: str, ontology_schema: str, ) -> str: try: return self._prepare_sparql_query(_run_manager, generated_sparql) except Exception as e: retries = 0 error_message = str(e) self._log_invalid_sparql_query( _run_manager, generated_sparql, error_message ) while retries < self.max_fix_retries: try: sparql_fix_chain_result = self.sparql_fix_chain.invoke( { "error_message": error_message, "generated_sparql": generated_sparql, "schema": ontology_schema, }, callbacks=callbacks, ) generated_sparql = sparql_fix_chain_result[ self.sparql_fix_chain.output_key ] return self._prepare_sparql_query(_run_manager, generated_sparql) except Exception as e: retries += 1 parse_exception = str(e) self._log_invalid_sparql_query( _run_manager, generated_sparql, parse_exception ) raise ValueError("The generated SPARQL query is invalid.") def _prepare_sparql_query( self, _run_manager: CallbackManagerForChainRun, generated_sparql: str ) -> str: from rdflib.plugins.sparql import prepareQuery prepareQuery(generated_sparql) self._log_prepared_sparql_query(_run_manager, generated_sparql) return generated_sparql def _log_prepared_sparql_query( self, _run_manager: CallbackManagerForChainRun, generated_query: str ) -> None: _run_manager.on_text("Generated SPARQL:", end="\n", verbose=self.verbose) _run_manager.on_text( generated_query, color="green", end="\n", verbose=self.verbose ) def _log_invalid_sparql_query( self, _run_manager: CallbackManagerForChainRun, generated_query: str, error_message: str, ) -> None: _run_manager.on_text("Invalid SPARQL query: ", end="\n", verbose=self.verbose) _run_manager.on_text( generated_query, color="red", end="\n", verbose=self.verbose ) _run_manager.on_text( "SPARQL Query Parse Error: ", end="\n", verbose=self.verbose ) _run_manager.on_text( error_message, color="red", end="\n\n", verbose=self.verbose ) def _execute_query(self, query: str) -> List[rdflib.query.ResultRow]: try: return self.graph.query(query) except Exception: raise ValueError("Failed to execute the generated SPARQL query.")