[英]SQLAlchemy Many-to-many table with multiple foreign key entires
我是sqlalchemy的新手,我想尽可能简单但正确地做到这一点。 我想每月跟踪多个公司之间的域名使用情况,因此我设置了以下表格:
class Company(Base):
__tablename__ = 'company'
id = Column(Integer, primary_key = True)
name = Column('name', String)
class Domains(Base):
__tablename__ = 'domains'
id = Column(Integer, primary_key=True)
name = Column('name', String, unique=True)
class MonthlyUsage(Base):
'''
Track domain usage across all
companies on a monthly basis.
'''
__tablename__ = 'monthlyusage'
month = Column(DateTime)
company_id = Column(Integer, ForeignKey('company.id'))
domain_id = Column(Integer, ForeignKey('domains.id'))
# <...other columns snipped out...>
company = relationship('Company', backref='company_assoc')
domain = relationship('Domains', backref='domain_assoc')
在我添加第二个月的使用详细信息之前,该方法可以正常工作。 然后,我得到重复的键值错误:
* sqlalchemy.exc.IntegrityError:(IntegrityError)重复键值违反了唯一约束“ monthlyusage_pkey” *
这是否意味着我必须将“每月使用量”分成第三张表? 这似乎不必要地复杂,因为唯一需要的是月份,company_id和domain_id字段。
对我的布局有什么建议,以使其尽可能简单但仍然正确?
TIA!
好的,我需要向MonthlyUsage添加一个主键列。 下面的代码现在可以工作了...
class MonthlyUsage(Base):
'''
Track domain usage across all
companies on a monthly basis.
'''
__tablename__ = 'monthlyusage'
month = Column(DateTime)
month_id = Column(Integer, primary_key=True)
company_id = Column(Integer, ForeignKey('company.id'), primary_key=True)
domain_id = Column(Integer, ForeignKey('domains.id'), primary_key=True)
# <...other columns snipped out...>
company = relationship('Company', backref='company_assoc')
domain = relationship('Domains', backref='domain_assoc')
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