Source code for langchain_community.chains.graph_qa.nebulagraph

"""Question answering over a graph."""

from __future__ import annotations

from typing import Any, Dict, List, Optional

from langchain.chains.base import Chain
from langchain.chains.llm import LLMChain
from langchain_core.callbacks import CallbackManagerForChainRun
from langchain_core.language_models import BaseLanguageModel
from langchain_core.prompts import BasePromptTemplate
from pydantic import Field

from langchain_community.chains.graph_qa.prompts import (
    CYPHER_QA_PROMPT,
    NGQL_GENERATION_PROMPT,
)
from langchain_community.graphs.nebula_graph import NebulaGraph




class NebulaGraphQAChain(Chain):
    """Chain for question-answering against a graph by generating nGQL 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: NebulaGraph = Field(exclude=True)
    ngql_generation_chain: LLMChain
    qa_chain: LLMChain
    input_key: str = "query"  #: :meta private:
    output_key: str = "result"  #: :meta private:

    allow_dangerous_requests: bool = False
    """Forced user opt-in to acknowledge that the chain can make dangerous requests.

    *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.
    """

    def __init__(self, **kwargs: Any) -> None:
        """Initialize the chain."""
        super().__init__(**kwargs)
        if self.allow_dangerous_requests is not True:
            raise ValueError(
                "In order to use this chain, you must acknowledge that it can make "
                "dangerous requests by setting `allow_dangerous_requests` to `True`."
                "You must narrowly scope the permissions of the database connection "
                "to only include necessary permissions. Failure to do so may result "
                "in data corruption or loss or reading sensitive data if such data is "
                "present in the database."
                "Only use this chain if you understand the risks and have taken the "
                "necessary precautions. "
                "See https://python.langchain.com/docs/security for more information."
            )

    @property
    def input_keys(self) -> List[str]:
        """Return the input keys.

        :meta private:
        """
        return [self.input_key]

    @property
    def output_keys(self) -> List[str]:
        """Return the output keys.

        :meta private:
        """
        _output_keys = [self.output_key]
        return _output_keys



    @classmethod
    def from_llm(
        cls,
        llm: BaseLanguageModel,
        *,
        qa_prompt: BasePromptTemplate = CYPHER_QA_PROMPT,
        ngql_prompt: BasePromptTemplate = NGQL_GENERATION_PROMPT,
        **kwargs: Any,
    ) -> NebulaGraphQAChain:
        """Initialize from LLM."""
        qa_chain = LLMChain(llm=llm, prompt=qa_prompt)
        ngql_generation_chain = LLMChain(llm=llm, prompt=ngql_prompt)

        return cls(
            qa_chain=qa_chain,
            ngql_generation_chain=ngql_generation_chain,
            **kwargs,
        )


    def _call(
        self,
        inputs: Dict[str, Any],
        run_manager: Optional[CallbackManagerForChainRun] = None,
    ) -> Dict[str, str]:
        """Generate nGQL 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]

        generated_ngql = self.ngql_generation_chain.run(
            {"question": question, "schema": self.graph.get_schema}, callbacks=callbacks
        )

        _run_manager.on_text("Generated nGQL:", end="\n", verbose=self.verbose)
        _run_manager.on_text(
            generated_ngql, color="green", end="\n", verbose=self.verbose
        )
        context = self.graph.query(generated_ngql)

        _run_manager.on_text("Full Context:", end="\n", verbose=self.verbose)
        _run_manager.on_text(
            str(context), color="green", end="\n", verbose=self.verbose
        )

        result = self.qa_chain(
            {"question": question, "context": context},
            callbacks=callbacks,
        )
        return {self.output_key: result[self.qa_chain.output_key]}