Hello.
I had a problem described in subject. Here is the testcase:
import sqlalchemy
engine = sqlalchemy.create_engine('sqlite:///:memory:')
metadata = sqlalchemy.MetaData(engine)
class ForeignKey(sqlalchemy.Column):
def __init__(self, name, foreign_column, *args, **kwargs):
fk = sqlalchemy.ForeignKey(foreign_column)
super(ForeignKey, self).__init__(name, fk, *args, **kwargs)
table1 = sqlalchemy.Table('table1', metadata,
sqlalchemy.Column('id', sqlalchemy.Integer)
)
table2 = sqlalchemy.Table('table2', metadata,
ForeignKey('fk', 'table1.id')
)
metadata.create_all()
It fails with really strange exception: "AttributeError: 'ForeignKey'
object has no attribute 'use_alter'". It was really hard to me to
track down the error's nature and I found that it came from here:
http://www.sqlalchemy.org/trac/browser/sqlalchemy/trunk/lib/sqlalchemy/sql/visitors.py#L29
I solved my problem by adding class property __visit_name__ = 'column'
to ForeignKey class. But I am a bit confused now and I have two
questions about the code in
sqlalchemy.sql.visitors.VisitableType.__init__()
1. What about another side-effects depending on clsname? Is it
actually safe to extend sqlalchemy.schema.Column, or it may have
unpredictable behavior similar to that i've encountered?
2. (almost offtopic) Is 'exec' really need there? What's wrong with
closures?
3. Maybe I should send it to developers mailing list?
Thanks.
--
Angri
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