On 03/02/2010 16:34, Adam Tauno Williams wrote:
I'm trying to convert a working non-declarative map of a two-entity
table to declarative style, but the join always fails with
"'_TextClause' object has no attribute 'foreign_keys'"
NON-DECLARATIVE STYLE (WORKING)
--------------------------------------------------
engine = create_engine('postgres://[email protected]/OGo', echo=True)
metadata = MetaData()
x1 = Table('job_history', metadata,
Column('job_history_id', Integer, Sequence('key_generator'),
primary_key=True),
Column('job_id', Integer),
Column('actor_id', Integer),
Column('action', String))
x2 = Table('job_history_info', metadata,
Column('job_history_info_id', Integer, Sequence('key_generator'),
primary_key=True),
Column('comment', String),
Column('job_history_id', Integer,
ForeignKey('job_history.job_history_id')))
x3 = join(x1, x2)
class Action(object):
pass
mapper(Action, x3)
Session = sessionmaker()
Session.configure(bind=engine)
db = Session()
z = Action()
z.job_id = 1
z.comment = 'TEST TEST TEST'
z.actor_id = 0
z.action = 'test'
db.add(z)
db.commit()
DECLARATIVE STYLE (FAILS)
-----------------------------------------------
engine = create_engine('postgres://[email protected]/OGo', echo=True)
Base = declarative_base()
class x1(Base):
__tablename__ = 'job_history'
id = Column('job_history_id', Integer,
Sequence('key_generator'), primary_key=True)
task_id = Column('job_id', Integer)
actor_id = Column('actor_id', Integer)
action = Column('action', String)
class x2(Base):
__tablename__ = 'job_history_info'
_info_id = Column('job_history_info_id', Integer,
Sequence('key_generator'), primary_key=True)
comment = Column('comment', String)
#FAILS _hist_id = Column('job_history_id', Integer,
ForeignKey('job_history.job_history_id'))
#FAILS _hist_id = Column('job_history_id', Integer,
ForeignKey('x1.id'))
#FAILS _hist_id = Column('job_history_id', Integer, ForeignKey(x1.id))
# Uncomment any one of the above for the same result.
x3 = join(x1, x2)
class Action(Base):
""" An OpenGroupare Task History Info entry """
__table__ = x3
Session = sessionmaker()
Session.configure(bind=engine)
db = Session()
z = Action()
z.job_id = 1
z.comment = 'TEST TEST TEST'
z.actor_id = 0
z.action = 'test'
db.add(z)
db.commit()
------------------------------------------------------
Why does this work in straight mapper code but not work in declarative?
This seems like a 1:1 correspondence.
STACK TRACE
----------------------------------------------------
Traceback (most recent call last):
File "./dec.py", line 26, in<module>
x3 = join(x1, x2)
File
"/usr/lib/python2.6/site-packages/SQLAlchemy-0.5.4p2-py2.6.egg/sqlalchemy/sql/expression.py",
line 123, in join
return Join(left, right, onclause, isouter)
File
"/usr/lib/python2.6/site-packages/SQLAlchemy-0.5.4p2-py2.6.egg/sqlalchemy/sql/expression.py",
line 2506, in __init__
self.onclause = self._match_primaries(self.left, self.right)
File
"/usr/lib/python2.6/site-packages/SQLAlchemy-0.5.4p2-py2.6.egg/sqlalchemy/sql/expression.py",
line 2552, in _match_primaries
return sql_util.join_condition(primary, secondary)
File
"/usr/lib/python2.6/site-packages/SQLAlchemy-0.5.4p2-py2.6.egg/sqlalchemy/sql/util.py",
line 100, in join_condition
for fk in b.foreign_keys:
AttributeError: '_TextClause' object has no attribute 'foreign_keys'
awill...@linux-m3mt:~>
I think this should work and means a bit less typing.
Base = declarative_base()
class x1(Base):
__tablename__ = 'job_history'
id = Column(Integer, Sequence('key_generator'), primary_key=True)
task_id = Column(Integer)
actor_id = Column(Integer)
action = Column(String)
class x2(Base):
__tablename__ = 'job_history_info'
_info_id = Column(Integer, Sequence('key_generator'), primary_key=True)
comment = Column(String)
_hist_id = Column(Integer, ForeignKey('job_history.id'))
Unless you need explicit names as described here.
http://www.sqlalchemy.org/docs/05/reference/ext/declarative.html
Werner
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