SQLAlchemy的'Connection'对象没有属性'_Inspector__engine'。

我想使用SQLAlchemy来读取未映射到对象的数据库（需要在开发时访问未知的数据库）。其中一个功能是读取不同表的列名。因此，我编写了这个连接器：\nMyConnector.py\n

import sqlalchemy as db
class MyConnector:
    __engine = None
    def __init__(self, db_connection):
        self.__engine = db.create_engine(db_connection)
    def __get_table(self, tbl_name):
        metadata = db.MetaData()
        table = db.Table(tbl_name, metadata)
        inspector = db.inspect(self.__engine)
        inspector.reflect_table(table, None)
        return table
    def get_table_columns(self, tbl_name):
        table = self.__get_table(tbl_name)
        return table.columns.keys()

\n通过以下单元测试对其进行了测试：\nConnectorTest.py\n

import unittest
from MyConnector import MyConnector
class MyTestCase(unittest.TestCase):
    db_string = "sqlite:///myTest.db"
    expected_columns_user = ["id", "f_name", "l_name", "note"]
    expected_columns_address = ["id", "street", "number", "postal_code", "additional_information", "fk_user"]
    def test_get_table_columns_user(self):
        connector = MyConnector(self.db_string)
        answer = connector.get_table_columns("user")
        self.assertListEqual(self.expected_columns_user, answer)
    def test_get_table_columns_address(self):
        connector = MyConnector(self.db_string)
        answer = connector.get_table_columns("address")
        self.assertListEqual(self.expected_columns_address, answer)
if __name__ == '__main__':
    unittest.main()

\nSQLite数据库仅包含以下两个空表：\n

CREATE TABLE user (
    id INTEGER NOT NULL DEFAULT AUTO_INCREMENT,
    f_name VARCHAR,
    l_name VARCHAR,
    note VARCHAR,
    PRIMARY KEY (
        id
    )
);
CREATE TABLE address (
    id INTEGER NOT NULL DEFAULT AUTO_INCREMENT,
    street VARCHAR NOT NULL,
    number INTEGER,
    postal_code INTEGER NOT NULL,
    additional_information VARCHAR,
    fk_user INTEGER NOT NULL,
    PRIMARY KEY (
        id
    ),
    FOREIGN KEY (
        fk_user
    )
    REFERENCES user(id) ON DELETE CASCADE
);

\n测试test_get_table_columns_user按预期工作。\n测试test_get_table_columns_address引发错误：\n

Error
Traceback (most recent call last):
  File "ConnectorTest.py", line 17, in test_get_table_columns_address
    answer = connector.get_table_columns("address")
  File "MyConnector.py", line 17, in get_table_columns
    table = self.__get_table(tbl_name)
  File "MyConnector.py", line 13, in __get_table
    inspector.reflect_table(table, None)
  File "venv\lib\site-packages\sqlalchemy\engine\reflection.py", line 802, in reflect_table
    reflection_options,
  File "venv\lib\site-packages\sqlalchemy\engine\reflection.py", line 988, in _reflect_fk
    **reflection_options
  File "", line 2, in __new__
  File "venv\lib\site-packages\sqlalchemy\util\deprecations.py", line 298, in warned
    return fn(*args, **kwargs)
  File "venv\lib\site-packages\sqlalchemy\sql\schema.py", line 601, in __new__
    metadata._remove_table(name, schema)
  File "venv\lib\site-packages\sqlalchemy\util\langhelpers.py", line 72, in __exit__
    with_traceback=exc_tb,
  File "venv\lib\site-packages\sqlalchemy\util\compat.py", line 207, in raise_
    raise exception
  File "venv\lib\site-packages\sqlalchemy\sql\schema.py", line 596, in __new__
    table._init(name, metadata, *args, **kw)
  File "venv\lib\site-packages\sqlalchemy\sql\schema.py", line 676, in _init
    resolve_fks=resolve_fks,
  File "venv\lib\site-packages\sqlalchemy\sql\schema.py", line 705, in _autoload
    with insp._inspection_context() as conn_insp:
  File "AppData\Local\Programs\Python\Python37\lib\contextlib.py", line 112, in __enter__
    return next(self.gen)
  File "venv\lib\site-packages\sqlalchemy\engine\reflection.py", line 217, in _inspection_context
    sub_insp = self._construct(self.__class__._init_connection, conn)
  File "venv\lib\site-packages\sqlalchemy\engine\reflection.py", line 117, in _construct
    init(self, bind)
  File "venv\lib\site-packages\sqlalchemy\engine\reflection.py", line 135, in _init_connection
    self.engine = connection.__engine
AttributeError: 'Connection' object has no attribute '_Inspector__engine'

\n由于两个测试运行的代码完全相同，除了表名参数，因此我对结果感到非常困惑。\n使用谷歌，我找到了这个 PR：https://github.com/laughingman7743/PyAthena/pull/65/files\n似乎与此问题无关（引擎而不是连接）。\n有很多关于会话的帖子（例如Python SQLAlchemy Query: AttributeError: \'Connection\' object has no attribute \'contextual_connect\'或https://github.com/sqlalchemy/sqlalchemy/issues/4046）。这应该不重要，因为在这个上下文中使用检查器似乎甚至不需要调用engine.connect()。\n为了排除潜在的锁定或类似问题，我还将test_get_table_columns_address的参数更改为\"user\"。这可以正确执行断言之前，显然不匹配。所以对我来说，这看起来是一个与表（-name？）相关的问题 - 这非常奇怪。\n有经验和了解SQLAlchemy的人能指出我的代码问题在哪里吗？提前谢谢！\nPython 3.7.4\nSQLAlchemy 1.4.20