On Aug 3, 2010, at 10:24 PM, jgs9000 wrote:
> Hi
>
> I'm relatively new to SQLAlchemy, so thanks in advance for any help
> with this issue.
>
> I'm trying to construct a class to model a legacy table which has a
> composite primary key which is also
> a composite foreign key referencing the composite primary key of a
> second table. I'm trying to define this
> class declaratively, and also have it autoload the remaining table
> structure from the underlying table.
i dont know that we have any tests which do a pure autoload plus a foreign key
constraint otherwise not associated with anything. so its likely a bug. you
might want to try calling table.append_constraint(constraint) after the
autoload completes.
>
> This is what I have:
>
> class Wcs(skymapper_db.db.TableBase):
>
> from sqlalchemy import Column, Integer, ForeignKeyConstraint
>
> __tablename__ = 'wcs'
> __table_args__ = (
> ForeignKeyConstraint(['image_id', 'amp'],
> ['science_amp.image_id', 'science_amp.amp']),
> {'autoload':True}
> )
>
> image_id = Column(Integer, primary_key=True)
> amp = Column(Integer, primary_key=True)
>
> def __init__(self):
> pass
>
> def __repr__(self):
> return "<Wcs(%s, %s)>" % (self.image_id, self.amp)
>
> As it stands, I get an error when I try to instantiate this class:
>
> C:\Users\jgs900\Work\skymapper-alchemy>wcs.py
> Traceback (most recent call last):
> File "C:\Users\jgs900\Work\skymapper-alchemy\wcs.py", line 13, in
> <module>
> class Wcs(skymapper_db.db.TableBase):
> File "C:\Python27\lib\site-packages\sqlalchemy\ext\declarative.py",
> line 1017, in __init__
> _as_declarative(cls, classname, cls.__dict__)
> File "C:\Python27\lib\site-packages\sqlalchemy\ext\declarative.py",
> line 926, in _as_declarative
> **table_kw)
> File "C:\Python27\lib\site-packages\sqlalchemy\schema.py", line 209,
> in __new__
> table._init(name, metadata, *args, **kw)
> File "C:\Python27\lib\site-packages\sqlalchemy\schema.py", line 269,
> in _init
> self._init_items(*args)
> File "C:\Python27\lib\site-packages\sqlalchemy\schema.py", line 60,
> in _init_items
> item._set_parent(self)
> File "C:\Python27\lib\site-packages\sqlalchemy\schema.py", line 809,
> in _set_parent
> table.constraints.remove(fk.constraint)
> KeyError: ForeignKeyConstraint()
>
> but if I leave out the autoload instruction, there is no problem.
>
> Am i doing something fundamentally wrong? Or am I just making a syntax
> error of some sort. Any help
> would be greatly appreciated.
>
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