类在 SQLalchemy 中没有名为“x”的映射列
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【中文标题】类在 SQLalchemy 中没有名为“x”的映射列【英文标题】:Class does not have a mapped column named 'x' in SQLalchemy 【发布时间】:2018-09-05 01:30:53 【问题描述】:我在 Django 环境中使用 SQLAlchemy (v1.2.11),因此我可以在 Firebird 数据库(由公司的 ERP 使用)和我在 Django 中开发的 Intranet 之间进行一些映射。我使用 declarative_base 进行映射,因为自省不起作用。
其中一个限制是 Firebird 本身(1.5 版),它没有多大帮助,而且我不能接触数据库,只能执行 SELECT 查询。
我想做的一件事是让用户在某些特定情况下创建报告并与 Firebird 数据交互,在我的 Django 项目中创建相关记录。
但是,在一个特定的映射中,我得到了
Class <class 'SalesDetail'> does not have a mapped column named 'seller_id'
当查询准备好并使用关系时。让我抓狂的是,我还在这个 ProductSells 类中映射了另外两个关系,它们非常相似并且工作正常。
首先,我的基本映射与我要查询的表相关 (SalesDetail):
class Sellers(Base):
__tablename__ = 'sellers'
seller_id = Column('seller_id', Integer)
company_id = Column('company_id', Integer)
name = Column('name', String)
__mapper_args__ =
'primary_key': [seller_id, company_id],
class Products(Base):
__tablename__ = 'products'
product_code = Column('product_code', Integer)
company_id = Column('company_id', Integer)
name = Column('name', String)
product_type = Column('product_type', String)
product_brand = Column(Integer, ForeignKey('brands.brand'))
brand_company = Column(Integer, ForeignKey('brands.company_id'))
status = Column('status', String)
brand = relationship(
'Brands',
primaryjoin=(
'and_('
'Products.product_brand == Brands.brand, '
'Products.brand_company == Brands.company_id'
')'
),
innerjoin=True
)
__mapper_args__ =
'primary_key': [product_code, company_id],
class Sales(Base):
__tablename__ = 'sales'
sale_id = Column('sale_id', Integer)
company_id = Column(Integer, ForeignKey('clients.company_id'))
sale_number = Column('sale_number', Integer)
client_id = Column(Integer, ForeignKey('clients.client_id'))
sale_date = Column('sale_date', Date)
status = Column('status', String)
client = relationship(
'Clients',
primaryjoin=(
'and_('
'Sales.client_id == Clients.client_id, '
'Sales.company_id == Clients.company_id'
')'
),
innerjoin=True
)
__mapper_args__ =
'primary_key': [sale_id, company_id],
这是我要查询的关系:
class SalesDetail(Base):
__tablename__ = 'sales_detail'
sale_id = Column(Integer, ForeignKey('sales.sale_id'))
sale_company = Column(Integer, ForeignKey('sales.company_id'))
sale_control = Column('sale_control', Integer)
product_code = Column(Integer, ForeignKey('products.product_code'))
product_company = Column(Integer, ForeignKey('products.company_id'))
seller_id = (Integer, ForeignKey('sellers.seller_id'))
seller_company = (Integer, ForeignKey('sellers.company_id'))
qty = Column('qty', Integer)
discount = Column('discount', Numeric)
seller = relationship(
'Sellers',
primaryjoin=(
'and_('
'SalesDetail.seller_id == Sellers.seller_id, '
'SalesDetail.seller_company == Sellers.company_id'
')'
),
innerjoin=True
)
product = relationship(
'Products',
primaryjoin=(
'and_('
'SalesDetail.product_code == Products.product_code, '
'SalesDetail.product_company == Products.company_id'
')'
),
innerjoin=True
)
sale = relationship(
'Sales',
primaryjoin=(
'and_('
'SalesDetail.sale_id == Sales.sale_id, '
'SalesDetail.sale_company == Sales.company_id'
')'
),
innerjoin=True
)
__mapper_args__ =
'primary_key': [sale_id, sale_company, sale_control],
我的查询是:
query = self.session.query(
SalesDetail.sale_id,
Sales.sale_date,
Sellers.seller_id,
Products.product_code,
Products.name,
SalesDetail.qty,
).join(
SalesDetail.sale,
SalesDetail.product,
SalesDetail.seller,
Products.brand
)
query = query.filter(and_(
Sales.sale_date >= start_date,
Sales.sale_date <= end_date,
Sales.status != 'CAN',
Sales.company_id == self.company.id,
Products.product_type == 'R',
Brands.name.in_(brands),
Sellers.seller_id > 1001,
Sellers.seller_id < 9000
)).order_by(
Sellers.seller_id,
Sales.sale_date,
Sales.sale_control
)
res = query.all()
这引发了一个异常:
Class <class 'src.erp.models.SalesDetail'> does not have a mapped column named 'seller_id'
但是,如果我将 SalesDetail 更改为:
class SalesDetail(Base):
__tablename__ = 'sales_detail'
sale_id = Column(Integer, ForeignKey('sales.sale_id'))
sale_company = Column(Integer, ForeignKey('sales.company_id'))
sale_control = Column('sale_control', Integer)
product_code = Column(Integer, ForeignKey('products.product_code'))
product_company = Column(Integer, ForeignKey('products.company_id'))
seller_id = Column('seller_id', Integer)
seller_company = ('company_id', Integer)
qty = Column('qty', Integer)
discount = Column('discount', Numeric)
如果我从 SalesDetail 中删除属性 seller,并更改我的查询:
query = self.session.query(
SalesDetail.sale_id,
Sales.sale_date,
SalesDetail.seller_id,
Products.product_code,
Products.name,
SalesDetail.qty,
).join(
SalesDetail.sale,
SalesDetail.product,
Products.brand
)
一切正常。有趣的是:我认为从 SalesDetail 到 Sales 和 Products 的关系是完全一样的,使用复合外键,它工作得很好。因此,复合键或我的 Firebird 数据库似乎没有问题。
当我设置断点时,我可以看到当 seller_id 和 seller_company 是 Mapper 类中的 ForeignKeys(sqlalchemy/orm /mapper.py)。
SQLAlchemy 代码中的堆栈跟踪是这样的:
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/query.py", line 2136, in join
from_joinpoint=from_joinpoint)
File "<string>", line 2, in _join
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/base.py", line 201, in generate
fn(self, *args[1:], **kw)
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/query.py", line 2243, in _join
right_entity = onclause.property.mapper
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/util/langhelpers.py", line 767, in __get__
obj.__dict__[self.__name__] = result = self.fget(obj)
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/attributes.py", line 215, in property
return self.comparator.property
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/util/langhelpers.py", line 767, in __get__
obj.__dict__[self.__name__] = result = self.fget(obj)
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/relationships.py", line 1354, in property
mapperlib.Mapper._configure_all()
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/mapper.py", line 1276, in _configure_all
configure_mappers()
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/mapper.py", line 3033, in configure_mappers
mapper._post_configure_properties()
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/mapper.py", line 1832, in _post_configure_properties
prop.init()
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/interfaces.py", line 183, in init
self.do_init()
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/relationships.py", line 1655, in do_init
self._process_dependent_arguments()
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/orm/relationships.py", line 1680, in _process_dependent_arguments
setattr(self, attr, attr_value())
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/ext/declarative/clsregistry.py", line 281, in __call__
x = eval(self.arg, globals(), self._dict)
File "<string>", line 1, in <module>
File "/home/alexandre/.virtualenvs/intranet-salao/lib/python3.5/site-packages/sqlalchemy/ext/declarative/clsregistry.py", line 213, in __getattr__
% (self.cls, key))
sqlalchemy.exc.InvalidRequestError: Class <class 'src.erp.models.SalesDetail'> does not have a mapped column named 'seller_id'
【问题讨论】:
【参考方案1】:这有点错字,但时不时会弹出。错误消息准确地告诉您出了什么问题:
seller_id = (Integer, ForeignKey('sellers.seller_id'))
创建一个元组,而不是Column
。你的意思是
seller_id = Column(Integer, ForeignKey('sellers.seller_id'))
seller_company
中也有同样的错字。
【讨论】:
我不敢相信。我以为我已经仔细检查了一切!非常感谢!以上是关于类在 SQLalchemy 中没有名为“x”的映射列的主要内容,如果未能解决你的问题,请参考以下文章
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