python - Sqlalchemy 引发 'NotImplementedError: Operator 'getitem' is not supported on this expression' When using 'hybrid_property' in mysql.SET
问题描述
大家好:
我成功创建了“用户”表,但未能将“用户”添加到表中。
蟒蛇版本:3.7.2
SQLAlchemy 1.3.18
- 创建权限枚举
from sqlalchemy.dialects.mysql import SET
from enum import Enum
class UserPermission(Enum):
A = auto()
B = auto()
- 声明“用户”表
class User(Base):
__tablename__ = 'user'
_permission = Column('permission', SET(*[name for name,value in UserPermission.__members__.items()]), comment = "user permission", nullable = False, default=set())
@hybrid_property
def permission(self):
'''
convert 'str' set to 'Enum' set
'''
permissionEnumSet = set()
for element in self._permission:
permissionEnumSet.add(UserPermission[element])
return permissionEnumSet
@permission.setter
def permission(self, permissionEnumSet):
'''
convert 'Enum' set to 'str' set
'''
self._permission = [permission.name for permission in permissionEnumSet]
- 向表中添加一个“用户”
with Session() as session:
user = User(permission = set([UserPermission.A])) # it raise 'NotImplementedError: Operator 'getitem' is not supported on this expression'
- 引发异常
File "./src/model.py", line 87, in permission
for element in self._permission:
File "/root/.pyenv/versions/3.7.2/lib/python3.7/site-packages/sqlalchemy/sql/operators.py", line 432, in __getitem__
return self.operate(getitem, index)
File "/root/.pyenv/versions/3.7.2/lib/python3.7/site-packages/sqlalchemy/orm/attributes.py", line 219, in operate
return op(self.comparator, *other, **kwargs)
File "/root/.pyenv/versions/3.7.2/lib/python3.7/site-packages/sqlalchemy/sql/operators.py", line 432, in __getitem__
return self.operate(getitem, index)
File "/root/.pyenv/versions/3.7.2/lib/python3.7/site-packages/sqlalchemy/orm/properties.py", line 367, in operate
return op(self.__clause_element__(), *other, **kwargs)
File "/root/.pyenv/versions/3.7.2/lib/python3.7/site-packages/sqlalchemy/sql/operators.py", line 432, in __getitem__
return self.operate(getitem, index)
File "/root/.pyenv/versions/3.7.2/lib/python3.7/site-packages/sqlalchemy/sql/elements.py", line 759, in operate
return op(self.comparator, *other, **kwargs)
File "/root/.pyenv/versions/3.7.2/lib/python3.7/site-packages/sqlalchemy/sql/operators.py", line 432, in __getitem__
return self.operate(getitem, index)
File "<string>", line 1, in <lambda>
File "/root/.pyenv/versions/3.7.2/lib/python3.7/site-packages/sqlalchemy/sql/type_api.py", line 67, in operate
return o[0](self.expr, op, *(other + o[1:]), **kwargs)
File "/root/.pyenv/versions/3.7.2/lib/python3.7/site-packages/sqlalchemy/sql/default_comparator.py", line 237, in _getitem_impl
_unsupported_impl(expr, op, other, **kw)
File "/root/.pyenv/versions/3.7.2/lib/python3.7/site-packages/sqlalchemy/sql/default_comparator.py", line 242, in _unsupported_impl
"Operator '%s' is not supported on " "this expression" % op.__name__
NotImplementedError: Operator 'getitem' is not supported on this expression
你有什么好主意吗?
解决方案
我认为它在分配之前已被实例化为“my.SET”对象,以便调用“hybird_property”。对象喜欢“无”,它不能被迭代。我使用下面的代码来检查它。
from collections.abc import Iterable
@hybrid_property
def permission(self):
permissionEnumSet = set()
if isinstance(self._permission ,Iterable):
for element in self._permission:
permissionEnumSet.add(UserPermission[element])
return permissionEnumSet
有用。你认为这样做可以吗?
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