#!/usr/bin/python
#
# Copyright 2020 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
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"""Utility functions used by the SQL reporter and reader.
"""
import os
from typing import Union
from sqlalchemy import create_engine
from sqlalchemy.engine import Engine
from sqlalchemy.engine.url import URL
from sqlalchemy.orm import sessionmaker
[docs]def sqlite_engine(location: str, verbose=False) -> Engine:
"""Currently this just creates a local sqlalchemy engine in a local file.
"""
if not location.endswith(".db"):
location = f"{location}.db"
return create_engine(f'sqlite:///{location}', echo=verbose)
[docs]def session_maker(e: Union[Engine, sessionmaker]) -> sessionmaker:
"""Returns a session maker from the specified Engine, or acts as identity if e
is already a sessionmaker.
"""
if isinstance(e, sessionmaker):
return e
return sessionmaker(bind=e)
[docs]def sqlite_file_exists(arg: Union[Engine, URL]) -> bool:
"""Taken from sqlalchemy-utils. We can import that library once we move to
potentially many databases, since it seems useful to NOT re-implement the
world once we release this thing, and folks can make their own DBs.
https://sqlalchemy-utils.readthedocs.io/en/latest/_modules/sqlalchemy_utils/functions/database.html#database_exists
"""
if isinstance(arg, Engine):
return sqlite_file_exists(arg.url)
database = arg.database
if not os.path.isfile(database) or os.path.getsize(database) < 100:
return False
with open(database, 'rb') as f:
header = f.read(100)
return header[:16] == b'SQLite format 3\x00'
[docs]def rep_string(instance):
"""Returns a pretty string representation for sqlalchemy classes."""
klass = instance.__class__
klassname = klass.__name__
ret = []
for k in sorted(klass.__dict__.keys()):
if k[0] != '_':
ret.append("{}='{}'".format(k, getattr(instance, k)))
args = ", ".join(ret)
return "<{}({})>".format(klassname, args)