Python:SqlAlchemy将现有视图映射到ORM对象

Question

我目前试图将postgreSQL数据库中的现有视图映射到python中的SqlAlchemy ORM对象。我的视图具有以下名称path_number_view，并将一些表连接在一起。很好。但是我无法将视图映射到ORM对象，当启动应用程序时，我得到一个错误（下面是代码）

我遵循这些指示

• Blog post
• Docs: Reflecting Database Objects
• Docs. Classical Mappings

但我不能让它工作

这是我的密码：

engine = create_engine("postgresql://****:*****@localhost/pi", pool_size=15, max_overflow=5, pool_recycle=1200)

Base = declarative_base(engine)
metadata = MetaData(engine)
path_number_view = Table('path_number_view', metadata,
                           Column('id', Integer, primary_key=True),
                           Column('path', String),
                           Column('threeDaysL', Integer),
                           Column('threeDaysC', Integer),
                           Column('tenDaysL', Integer),
                           Column('tenDaysC', Integer),
                           Column('number', Integer),
                           autoload=True
                           )


class PathNumberView(object):
    __tablename__ = 'path_number_view'

    def __init__(self, id, path, threeDaysL, threeDaysC, tenDaysL, tenDaysC, number):
        self.id = id
        self.path = path
        self.threeDaysL = threeDaysL
        self.threeDaysC = threeDaysC
        self.tenDaysL = tenDaysL
        self.tenDaysC = tenDaysC
        self.number = number


mapper(PathNumberView, path_number_view )

Base.metadata.create_all(engine)

我得到的错误没有帮助：

Traceback (most recent call last):
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\base.py", line 2265, in _wrap_pool_connect
    return fn()
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 363, in connect
    return _ConnectionFairy._checkout(self)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 760, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 492, in checkout
    rec = pool._do_get()
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\impl.py", line 139, in _do_get
    self._dec_overflow()
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\util\langhelpers.py", line 68, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\util\compat.py", line 153, in reraise
    raise value
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\impl.py", line 136, in _do_get
    return self._create_connection()
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 308, in _create_connection
    return _ConnectionRecord(self)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 437, in __init__
    self.__connect(first_connect_check=True)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 639, in __connect
    connection = pool._invoke_creator(self)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\strategies.py", line 114, in connect
    return dialect.connect(*cargs, **cparams)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\default.py", line 453, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\psycopg2\__init__.py", line 126, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
psycopg2.OperationalError

The above exception was the direct cause of the following exception:

Traceback (most recent call last):
  File "C:\Program Files\JetBrains\PyCharm 2018.3.5\helpers\pycharm\_jb_unittest_runner.py", line 35, in <module>
    main(argv=args, module=None, testRunner=unittestpy.TeamcityTestRunner, buffer=not JB_DISABLE_BUFFERING)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\unittest\main.py", line 94, in __init__
    self.parseArgs(argv)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\unittest\main.py", line 141, in parseArgs
    self.createTests()
  File "C:\Users\username\.conda\envs\tfGPU2\lib\unittest\main.py", line 148, in createTests
    self.module)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\unittest\loader.py", line 219, in loadTestsFromNames
    suites = [self.loadTestsFromName(name, module) for name in names]
  File "C:\Users\username\.conda\envs\tfGPU2\lib\unittest\loader.py", line 219, in <listcomp>
    suites = [self.loadTestsFromName(name, module) for name in names]
  File "C:\Users\username\.conda\envs\tfGPU2\lib\unittest\loader.py", line 153, in loadTestsFromName
    module = __import__(module_name)
  File "E:\Projekte\project\preprocessing\tests.py", line 6, in <module>
    from preprocessing.data import TrainingDataProvider
  File "E:\Projekte\project\preprocessing\data\__init__.py", line 7, in <module>
    from entity import PathNumberView
  File "E:\Projekte\project\entity\__init__.py", line 105, in <module>
    Base.metadata.create_all(engine)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\sql\schema.py", line 4294, in create_all
    ddl.SchemaGenerator, self, checkfirst=checkfirst, tables=tables
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\base.py", line 2035, in _run_visitor
    with self._optional_conn_ctx_manager(connection) as conn:
  File "C:\Users\username\.conda\envs\tfGPU2\lib\contextlib.py", line 81, in __enter__
    return next(self.gen)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\base.py", line 2027, in _optional_conn_ctx_manager
    with self._contextual_connect() as conn:
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\base.py", line 2229, in _contextual_connect
    self._wrap_pool_connect(self.pool.connect, None),
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\base.py", line 2269, in _wrap_pool_connect
    e, dialect, self
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\base.py", line 1536, in _handle_dbapi_exception_noconnection
    util.raise_from_cause(sqlalchemy_exception, exc_info)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\util\compat.py", line 398, in raise_from_cause
    reraise(type(exception), exception, tb=exc_tb, cause=cause)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\util\compat.py", line 152, in reraise
    raise value.with_traceback(tb)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\base.py", line 2265, in _wrap_pool_connect
    return fn()
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 363, in connect
    return _ConnectionFairy._checkout(self)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 760, in _checkout
    fairy = _ConnectionRecord.checkout(pool)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 492, in checkout
    rec = pool._do_get()
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\impl.py", line 139, in _do_get
    self._dec_overflow()
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\util\langhelpers.py", line 68, in __exit__
    compat.reraise(exc_type, exc_value, exc_tb)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\util\compat.py", line 153, in reraise
    raise value
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\impl.py", line 136, in _do_get
    return self._create_connection()
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 308, in _create_connection
    return _ConnectionRecord(self)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 437, in __init__
    self.__connect(first_connect_check=True)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\pool\base.py", line 639, in __connect
    connection = pool._invoke_creator(self)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\strategies.py", line 114, in connect
    return dialect.connect(*cargs, **cparams)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\sqlalchemy\engine\default.py", line 453, in connect
    return self.dbapi.connect(*cargs, **cparams)
  File "C:\Users\username\.conda\envs\tfGPU2\lib\site-packages\psycopg2\__init__.py", line 126, in connect
    conn = _connect(dsn, connection_factory=connection_factory, **kwasync)
sqlalchemy.exc.OperationalError: (psycopg2.OperationalError) 
(Background on this error at: http://sqlalche.me/e/e3q8)

连接本身正在工作，我还有3个其他表（使用SQLAclhemy创建）工作正常。我可以查询，更新，删除没有问题