Adding this to the test shows that the generated sql does retrieve 3 rows as
expected.
for r in sess.execute(q):
print r
I suspect it has something to do with the identity mapping. Maybe someone
who understands that could help with an explanation. Knowing my data, I
could have a similar problem.
--
Mike Conley
On Sun, Apr 19, 2009 at 2:45 PM, Alessandro Dentella <san...@e-den.it>wrote:
>
> Hi,
>
> i'm playing with outerjoin defined in the mapper. I'm getting results
> different from what I expected, so that I would like to understand which is
> the underline logic.
>
> Where a Query w/ outerjoin SELECT has in the backend n rows and would have
> m
> rows in a simple join, I only get m rows plus one 'None' for all the
> others.
>
> I would have thought to get one instance for each output of the query, am I
> wrong?
>
> tanks in advance
> sandro
> *:-)
>
> The example:
>
> from sqlalchemy.ext.declarative import declarative_base
> from sqlalchemy import Table, Column, ForeignKey, text, func
> from sqlalchemy.types import *
> from sqlalchemy.orm import relation, sessionmaker, mapper, column_property
> from sqlalchemy.orm.interfaces import SessionExtension
> from datetime import datetime, timedelta
>
> Base = declarative_base()
> Base.metadata.bind = 'sqlite://'
> Session = sessionmaker(bind=Base.metadata.bind)
> sess = Session()
>
> class Entry(Base):
> __tablename__ = 'calendar_entry' # Todo and Events
> id = Column(Integer, primary_key=True)
> summary = Column(String(100))
> dtstart = Column(DateTime(timezone=False), nullable=False,
> index=True)
>
> class Alarm(Base):
> __tablename__ = 'calendar_alarm'
>
> ida = Column(Integer, primary_key=True)
> trigger = Column(Interval, nullable=False)
>
> # o2m
> entry_id = Column(ForeignKey(Entry.id), nullable=False)
> entry = relation(Entry, backref='alarm', lazy=True)
>
> Base.metadata.create_all()
>
> e1 = Entry(summary="sum1", dtstart=datetime.now())
> e2 = Entry(summary="sum2", dtstart=datetime.now())
> a = Alarm(trigger=timedelta(days=1))
> ea1 = Entry(summary="entry w/ alarm", dtstart=datetime.now(),alarm=[a])
>
>
> for e in (e1, e2, ea1, a):
> sess.add(e)
>
> sess.commit()
>
> entry_table = Entry.__table__
> alarm_table = Alarm.__table__
>
> class MyJoin(object):
> def __str__(self):
> return "%s" % self.dtstart
>
> m = mapper(MyJoin, entry_table.outerjoin(alarm_table), )
>
>
> q = sess.query(m)
> print q.count()
> for r in q.all():
> print r
> ------------------- with result --------------
>
> 3 # count for the matches
> None ???
> 2009-04-19 20:34:04.188442 # the only joined entry (entry w/ alarm)
>
> >
>
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