[英]sqlalchemy: How can I associate object of other table with primary key?
I have a Transaction
table as 我有一个
Transaction
表
class Transaction(Base):
__tablename__ = 'transaction'
id = Column('id', Integer, primary_key=True)
name = Column('name', String)
amount = Column('amount', Float)
category_id = Column('category_id', Integer, ForeignKey('category.id'))
date_created = Column('date_created', Date, default=datetime.now())
date_modified = Column('date_modifed', Date, onupdate=datetime.now())
and Category
table as 和
Category
表为
class Category(Base):
__tablename__ = 'category'
id = Column('id', Integer, primary_key=True)
name = Column('name', String)
subtype = Column('subtype', String)
I add the transaction dataset as 我将交易数据集添加为
name, amount, category_id
Costo,59.0,5
Costo,20,5
Safeway,6.75,1
Safeway,11,1
Safeway,19,1
and I can see them as well when I query them 当我查询它们时,我也可以看到它们
for transaction in session.query(Transaction):
logging.info(transaction)
and I see the data as well 我也看到了数据
INFO:root:<Transaction(22, Medical Insurance, 110.0, 62, 2013-03-09, None)>
INFO:root:<Transaction(23, AllState Renter Insurance, 100.0, 77, 2013-03-09, None)>
But I do see the categoty_id
as 62 and 77 . 但是我确实看到
categoty_id
为62和77 。
All I need the their values as objects like 我只需要它们的值作为对象
INFO:root:<Transaction(22, Medical Insurance, 110.0, **Medical**, 2013-03-09, None)>
INFO:root:<Transaction(23, AllState Renter Insurance, 100.0, **Insurance**, 2013-03-09, None)>
How can I attach the objects of different table? 如何附加不同表的对象?
I am sure just using primary_key
will not suffice, but what else I need to do? 我确定仅使用
primary_key
还是不够的,但是我还需要做什么? Please advice 请指教
I have just started learning about SQLAlchemy
我刚刚开始学习
SQLAlchemy
You probably need to create a relationship()
: http://docs.sqlalchemy.org/en/latest/orm/relationships.html 您可能需要创建一个
relationship()
: http : //docs.sqlalchemy.org/en/latest/orm/relationships.html
from sqlalchemy.orm import relationship, backref
class Category(Base):
__tablename__ = 'category'
id = Column('id', Integer, primary_key=True)
name = Column('name', String)
subtype = Column('subtype', String)
# This line is new
transactions = relationship("Transaction", backref="category")
I'm not sure if I entirely understood your question, but this should attach a transactions
attribute to each category containing a collection of associated items. 我不确定我是否完全理解您的问题,但这应该将
transactions
属性附加到包含关联项目集合的每个类别。 Or alternatively: 或者:
class Transaction(Base):
__tablename__ = 'transaction'
id = Column('id', Integer, primary_key=True)
name = Column('name', String)
amount = Column('amount', Float)
category_id = Column('category_id', Integer, ForeignKey('category.id'))
date_created = Column('date_created', Date, default=datetime.now())
date_modified = Column('date_modifed', Date, onupdate=datetime.now())
category = relationship("category")
to attach objects many-to-one in the opposite direction (as @daydreamer already figured out). 以相反的方向多对一地附加对象(如@daydreamer已经弄清楚的)。
After adding the following line in my Transaction
, I was able to refer to the Category
associated with the transaction 在我的
Transaction
添加以下行后,我能够引用与该交易相关联的Category
category = relationship('Category')
My class Transaction
finally looks like 我的班级
Transaction
终于看起来像
class Transaction(Base):
__tablename__ = 'transaction'
id = Column('id', Integer, primary_key=True)
name = Column('name', String)
amount = Column('amount', Float)
category_id = Column('category_id', Integer, ForeignKey('category.id'))
date_created = Column('date_created', Date, default=datetime.now())
date_modified = Column('date_modifed', Date, onupdate=datetime.now())
category = relationship('Category')
and I can see the output as 我可以看到输出为
INFO:root:<Transaction(28, ATT, 89.0, <Category(148, Utilities, Phone)>, 2013-03-09, None)>
INFO:root:<Transaction(27, Car Gas, 47.0, <Category(146, Utilities, Gas & Fuel)>, 2013-03-09, None)>
Thanks to @David Marx for pointing to the right documentation 感谢@David Marx指出正确的文档
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