"""Question answering over a graph."""
from __future__ import annotations
import re
from typing import Any, Dict, List, Optional
from pydantic import Field
from langchain.base_language import BaseLanguageModel
from langchain.callbacks.manager import CallbackManagerForChainRun
from langchain.chains.base import Chain
from langchain.chains.graph_qa.prompts import (
AQL_FIX_PROMPT,
AQL_GENERATION_PROMPT,
AQL_QA_PROMPT,
)
from langchain.chains.llm import LLMChain
from langchain.graphs.arangodb_graph import ArangoGraph
from langchain.schema import BasePromptTemplate
[docs]class ArangoGraphQAChain(Chain):
"""Chain for question-answering against a graph by generating AQL statements."""
graph: ArangoGraph = Field(exclude=True)
aql_generation_chain: LLMChain
aql_fix_chain: LLMChain
qa_chain: LLMChain
input_key: str = "query" #: :meta private:
output_key: str = "result" #: :meta private:
# Specifies the maximum number of AQL Query Results to return
top_k = 10
# Specifies the set of AQL Query Examples that promote few-shot-learning
aql_examples = ""
# Specify whether to return the AQL Query in the output dictionary
return_aql_query: bool = False
# Specify whether to return the AQL JSON Result in the output dictionary
return_aql_result: bool = False
# Specify the maximum amount of AQL Generation attempts that should be made
max_aql_generation_attempts = 3
@property
def input_keys(self) -> List[str]:
return [self.input_key]
@property
def output_keys(self) -> List[str]:
return [self.output_key]
@property
def _chain_type(self) -> str:
return "graph_aql_chain"
[docs] @classmethod
def from_llm(
cls,
llm: BaseLanguageModel,
*,
qa_prompt: BasePromptTemplate = AQL_QA_PROMPT,
aql_generation_prompt: BasePromptTemplate = AQL_GENERATION_PROMPT,
aql_fix_prompt: BasePromptTemplate = AQL_FIX_PROMPT,
**kwargs: Any,
) -> ArangoGraphQAChain:
"""Initialize from LLM."""
qa_chain = LLMChain(llm=llm, prompt=qa_prompt)
aql_generation_chain = LLMChain(llm=llm, prompt=aql_generation_prompt)
aql_fix_chain = LLMChain(llm=llm, prompt=aql_fix_prompt)
return cls(
qa_chain=qa_chain,
aql_generation_chain=aql_generation_chain,
aql_fix_chain=aql_fix_chain,
**kwargs,
)
def _call(
self,
inputs: Dict[str, Any],
run_manager: Optional[CallbackManagerForChainRun] = None,
) -> Dict[str, Any]:
"""
Generate an AQL statement from user input, use it retrieve a response
from an ArangoDB Database instance, and respond to the user input
in natural language.
Users can modify the following ArangoGraphQAChain Class Variables:
:var top_k: The maximum number of AQL Query Results to return
:type top_k: int
:var aql_examples: A set of AQL Query Examples that are passed to
the AQL Generation Prompt Template to promote few-shot-learning.
Defaults to an empty string.
:type aql_examples: str
:var return_aql_query: Whether to return the AQL Query in the
output dictionary. Defaults to False.
:type return_aql_query: bool
:var return_aql_result: Whether to return the AQL Query in the
output dictionary. Defaults to False
:type return_aql_result: bool
:var max_aql_generation_attempts: The maximum amount of AQL
Generation attempts to be made prior to raising the last
AQL Query Execution Error. Defaults to 3.
:type max_aql_generation_attempts: int
"""
_run_manager = run_manager or CallbackManagerForChainRun.get_noop_manager()
callbacks = _run_manager.get_child()
user_input = inputs[self.input_key]
#########################
# Generate AQL Query #
aql_generation_output = self.aql_generation_chain.run(
{
"adb_schema": self.graph.schema,
"aql_examples": self.aql_examples,
"user_input": user_input,
},
callbacks=callbacks,
)
#########################
aql_query = ""
aql_error = ""
aql_result = None
aql_generation_attempt = 1
while (
aql_result is None
and aql_generation_attempt < self.max_aql_generation_attempts + 1
):
#####################
# Extract AQL Query #
pattern = r"```(?i:aql)?(.*?)```"
matches = re.findall(pattern, aql_generation_output, re.DOTALL)
if not matches:
_run_manager.on_text(
"Invalid Response: ", end="\n", verbose=self.verbose
)
_run_manager.on_text(
aql_generation_output, color="red", end="\n", verbose=self.verbose
)
raise ValueError(f"Response is Invalid: {aql_generation_output}")
aql_query = matches[0]
#####################
_run_manager.on_text(
f"AQL Query ({aql_generation_attempt}):", verbose=self.verbose
)
_run_manager.on_text(
aql_query, color="green", end="\n", verbose=self.verbose
)
#####################
# Execute AQL Query #
from arango import AQLQueryExecuteError
try:
aql_result = self.graph.query(aql_query, self.top_k)
except AQLQueryExecuteError as e:
aql_error = e.error_message
_run_manager.on_text(
"AQL Query Execution Error: ", end="\n", verbose=self.verbose
)
_run_manager.on_text(
aql_error, color="yellow", end="\n\n", verbose=self.verbose
)
########################
# Retry AQL Generation #
aql_generation_output = self.aql_fix_chain.run(
{
"adb_schema": self.graph.schema,
"aql_query": aql_query,
"aql_error": aql_error,
},
callbacks=callbacks,
)
########################
#####################
aql_generation_attempt += 1
if aql_result is None:
m = f"""
Maximum amount of AQL Query Generation attempts reached.
Unable to execute the AQL Query due to the following error:
{aql_error}
"""
raise ValueError(m)
_run_manager.on_text("AQL Result:", end="\n", verbose=self.verbose)
_run_manager.on_text(
str(aql_result), color="green", end="\n", verbose=self.verbose
)
########################
# Interpret AQL Result #
result = self.qa_chain(
{
"adb_schema": self.graph.schema,
"user_input": user_input,
"aql_query": aql_query,
"aql_result": aql_result,
},
callbacks=callbacks,
)
########################
# Return results #
result = {self.output_key: result[self.qa_chain.output_key]}
if self.return_aql_query:
result["aql_query"] = aql_query
if self.return_aql_result:
result["aql_result"] = aql_result
return result