[英]sqlalchemy: How can I associate object of other table with primary key?
我有一個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())
和Category
表為
class Category(Base):
__tablename__ = 'category'
id = Column('id', Integer, primary_key=True)
name = Column('name', String)
subtype = Column('subtype', String)
我將交易數據集添加為
name, amount, category_id
Costo,59.0,5
Costo,20,5
Safeway,6.75,1
Safeway,11,1
Safeway,19,1
當我查詢它們時,我也可以看到它們
for transaction in session.query(Transaction):
logging.info(transaction)
我也看到了數據
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)>
但是我確實看到categoty_id
為62和77 。
我只需要它們的值作為對象
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)>
如何附加不同表的對象?
我確定僅使用primary_key
還是不夠的,但是我還需要做什么? 請指教
我剛剛開始學習SQLAlchemy
您可能需要創建一個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")
我不確定我是否完全理解您的問題,但這應該將transactions
屬性附加到包含關聯項目集合的每個類別。 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")
以相反的方向多對一地附加對象(如@daydreamer已經弄清楚的)。
在我的Transaction
添加以下行后,我能夠引用與該交易相關聯的Category
category = relationship('Category')
我的班級Transaction
終於看起來像
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')
我可以看到輸出為
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)>
感謝@David Marx指出正確的文檔
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