> -----Original Message-----
> From: sqlalchemy@googlegroups.com
> [mailto:sqlalch...@googlegroups.com] On Behalf Of darkblueB
> Sent: 19 August 2009 02:58
> To: sqlalchemy
> Subject: [sqlalchemy] Re: new questions
>
> Hi Simon
>
> thanks for the reply.. Your second part is straightforward..
> The first one, not so much..
>
> I have gone back to a simple
> meta.bind = //my engine here
> meta.reflect()
>
> I can see meta.tables, and meta.tables_sorted()
> but how do I know what mapped objects exist?
>
> (there should be about 12 tables, with a few one to many and one many
> to many defined)
> I feel like time is passing by, I would like to use ORM but this is
> new to me
> thanks much
> -Brian
>
Ah - I see what you mean now. meta.reflect() will only create Table
objects (part of the SQL expression language layer). It doesn't
automatically create mapped classes for you. If you want to use the
declarative system, you would need to create at least a basic class for
each of your reflected tables.
For example (untested):
import sqlalchemy as sa
from sqlalchemy.ext.declarative import declarative_base
meta = sa.Metadata(bind='sqlite:///your.db')
meta.reflect()
Base = declarative_base(metadata=meta)
class SomeObject(Base):
__table__ = meta.tables['some_table']
class SomeOtherObject(Base):
__table__ = meta.tables['some_other_table']
I suppose you could automate this by iterating over meta.tables and
creating the classes in a loop. You would end up with something similar
to SqlSoup (http://www.sqlalchemy.org/trac/wiki/SqlSoup). I suppose it
should be possible to automatically create ORM-level relations by
inspecting your foreign keys as well if you really wanted.
Simon
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