On Apr 19, 2013, at 11:01 AM, James Hartley <jjhart...@gmail.com> wrote:
> On Wed, Apr 17, 2013 at 2:59 PM, Michael Bayer <mike...@zzzcomputing.com>
> wrote:
>> James Hartley <jjhart...@gmail.com> writes:
>> > Is it possible to map Table instances back to classes defined through
>> > declarative_base()?
>
> the typical form is:
>
> Base = declarative_base()
>
> some_table = Table('some_table', Base.metadata, Column('id', Integer,
> primary_key=True))
>
> class SomeClass(Base):
> __table__ = some_table
>
> Thanks all for the responses.
>
> The Wiki recipe for views:
>
> http://www.sqlalchemy.org/trac/wiki/UsageRecipes/Views
>
> ...creates & drops the defined view on-the-fly. This raises two questions.
> Is there a way to allow the view created in Python code to persist?
when you emit "CREATE VIEW", which is what that recipe helps you do, that's a
persistent view in the database.
> Likewise, is there a way to take advantage of an existing view defined at the
> database level?
Sure, you'd make a Table object, giving it the name of the view as well as the
columns that the view returns. Then you just SELECT from it normally. This
can also be accomplished via reflection, Table("myview", metadata,
autoload=True, autoload_with=engine).
> An obvious workaround is to create a duplicate view with a different name,
> but I'm curious as to whether the two can be merged.
for a more integrated approach, the "def view()" in the recipe can be enhanced
to allow a "reflect from database" argument, or a list of columns, something
like that. It's a recipe so that it illustrates techniques which you can alter
to suit your specific needs.
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