SQLAlchemy-TypeError：_get_column_info() 得到了一个意外的关键字参数“生成”

Question

我正在尝试从 Redshift 数据库中获取表的元数据。 即使连接正常，我也会收到错误消息。 "TypeError: _get_column_info() 得到了一个意外的关键字参数 'generated'"

我尝试使用不同服务器的另一个数据库，它工作正常...... 但不确定此服务器表有什么问题。 你能帮我解决一下吗？

Table=sa.Table("Tablename" ,metadata,autoload=True,autoload_with=engine)

---

TypeError                                 Traceback (most recent call last)
<ipython-input-98-366ec112cf52> in <module>
----> 1 Table=sa.Table("dim_dealer" ,metadata,autoload=True,autoload_with=engine)

<string> in __new__(cls, *args, **kw)

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\util\deprecations.py in warned(fn, *args, **kwargs)
    126                     )
    127 
--> 128             return fn(*args, **kwargs)
    129 
    130         doc = fn.__doc__ is not None and fn.__doc__ or ""

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\sql\schema.py in __new__(cls, *args, **kw)
    494             except:
    495                 with util.safe_reraise():
--> 496                     metadata._remove_table(name, schema)
    497 
    498     @property

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\util\langhelpers.py in __exit__(self, type_, value, traceback)
     66             self._exc_info = None  # remove potential circular references
     67             if not self.warn_only:
---> 68                 compat.reraise(exc_type, exc_value, exc_tb)
     69         else:
     70             if not compat.py3k and self._exc_info and self._exc_info[1]:

~\AppData\Local\Continuum\anaconda3\lib\`enter code here`site-packages\sqlalchemy\util\compat.py in reraise(tp, value, tb, cause)
    151         if value.__traceback__ is not tb:
    152             raise value.with_traceback(tb)
--> 153         raise value
    154 
    155     def u(s):

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\sql\schema.py in __new__(cls, *args, **kw)
    489             metadata._add_table(name, schema, table)
    490             try:
--> 491                 table._init(name, metadata, *args, **kw)
    492                 table.dispatch.after_parent_attach(table, metadata)
    493                 return table

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\sql\schema.py in _init(self, name, metadata, *args, **kwargs)
    583                 include_columns,
    584                 _extend_on=_extend_on,
--> 585                 resolve_fks=resolve_fks,
    586             )
    587 

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\sql\schema.py in _autoload(self, metadata, autoload_with, include_columns, exclude_columns, resolve_fks, _extend_on)
    607                 exclude_columns,
    608                 resolve_fks,
--> 609                 _extend_on=_extend_on,
    610             )
    611         else:

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\engine\base.py in run_callable(self, callable_, *args, **kwargs)
   2148         """
   2149         with self._contextual_connect() as conn:
-> 2150             return conn.run_callable(callable_, *args, **kwargs)
   2151 
   2152     def execute(self, statement, *multiparams, **params):

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\engine\base.py in run_callable(self, callable_, *args, **kwargs)
   1602 
   1603         """
-> 1604         return callable_(self, *args, **kwargs)
   1605 
   1606     def _run_visitor(self, visitorcallable, element, **kwargs):

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\engine\default.py in reflecttable(self, connection, table, include_columns, exclude_columns, resolve_fks, **opts)
    429         insp = reflection.Inspector.from_engine(connection)
    430         return insp.reflecttable(
--> 431             table, include_columns, exclude_columns, resolve_fks, **opts
    432         )
    433 

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\engine\reflection.py in reflecttable(self, table, include_columns, exclude_columns, resolve_fks, _extend_on)
    638 
    639         for col_d in self.get_columns(
--> 640             table_name, schema, **table.dialect_kwargs
    641         ):
    642             found_table = True

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\engine\reflection.py in get_columns(self, table_name, schema, **kw)
    371 
    372         col_defs = self.dialect.get_columns(
--> 373             self.bind, table_name, schema, info_cache=self.info_cache, **kw
    374         )
    375         for col_def in col_defs:

<string> in get_columns(self, connection, table_name, schema, **kw)

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy\engine\reflection.py in cache(fn, self, con, *args, **kw)
     54     ret = info_cache.get(key)
     55     if ret is None:
---> 56         ret = fn(self, con, *args, **kw)
     57         info_cache[key] = ret
     58     return ret

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy_redshift\dialect.py in get_columns(self, connection, table_name, schema, **kw)
    459                 default=col.default, notnull=col.notnull, domains=domains,
    460                 enums=[], schema=col.schema, encode=col.encode,
--> 461                 comment=col.comment)
    462             columns.append(column_info)
    463         return columns

~\AppData\Local\Continuum\anaconda3\lib\site-packages\sqlalchemy_redshift\dialect.py in _get_column_info(self, *args, **kwargs)
    666         column_info = super(RedshiftDialect, self)._get_column_info(
    667             *args,
--> 668             **kw
    669         )
    670         if isinstance(column_info['type'], VARCHAR):

TypeError: _get_column_info() got an unexpected keyword argument 'generated'

print(repr(metadata.tables[Table]))

提前致谢

Answer 1

它看起来像 SQLAlchemy 和 SQLAlchemy-Redshift 之间的 backwards compatibility bug。

私有方法 RedshiftDialect._get_column_info 在 SQLAlchemy-Redshift 中被覆盖。在 SQLAlchemy v1.3.16 中此方法中添加了generated 关键字参数，导致兼容性错误。所以对这个问题进行了修复：generated 关键字应该只用于最新版本的 SQLAlchemy。不幸的是，它不起作用：

if sa.__version__ >= '1.3.16':
    # SQLAlchemy 1.3.16 introduced generated columns,
    # not supported in redshift
    kw['generated'] = ''

如您所见，此条件对于您的 SQLAlchemy 版本（“1.3.7”）是真实的，因为这是字符串比较的工作方式。我想我会提出一个拉取请求来纠正这种行为。

我认为目前最简单的解决方案是将 SQLAlchemy 包更新到 1.3.10 或更高版本。在这种情况下，此条件将按预期工作。

更新：此错误已在 SQLAlchemy-Redshift v0.8.0 中修复。