from sqlalchemy import Column, DateTime, String, Integer, ForeignKey, func,
Table, create_engine
from sqlalchemy.orm import relationship, backref, sessionmaker, joinedload,
contains_eager
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()
engine = create_engine('sqlite://', echo=True)
class Game(Base):
__tablename__ = 'game'
id = Column(Integer, primary_key=True)
stadium_name = Column(String)
month_id = Column(Integer, ForeignKey('month.id'))
year_stadium = relationship("YearStadium", secondary="month",
primaryjoin="Month.id == Game.month_id",
secondaryjoin="and_(Month.year_name == YearStadium.year_name, "
"YearStadium.stadium_name == Game.stadium_name)")
class Month(Base):
__tablename__ = 'month'
id = Column(Integer, primary_key=True)
year_name = Column(String)
class YearStadium(Base):
__tablename__ = 'year_stadium'
id = Column(Integer, primary_key=True)
stadium_name = Column(String)
year_name = Column(String)
Base.metadata.drop_all(engine)
Base.metadata.create_all(engine)
Session = sessionmaker(engine)
session = Session()
session.query(Game).join(Game.year_stadium).all() # works
session.query(Game).options(joinedload(Game.year_stadium)) # fails
In the example above, I'm trying to have a relationship to a table. It's
not a classic association table example, since the third table needs one
column from table 2 and one column from table 1 to be joined.
The relationship I wrote works well for simple joins or when lazy-loading,
but fails with a joinedload.
Is there a way to make it work ?
--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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