Re: [sqlalchemy] views declarative?
On Wed, Apr 17, 2013 at 2:59 PM, Michael Bayer mike...@zzzcomputing.comwrote:
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? Likewise, is there a way to take advantage of an existing view
defined at the database level? 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.
Thanks again for the insight shared.
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Re: [sqlalchemy] views declarative?
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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Re: [sqlalchemy] views declarative?
On Apr 17, 2013, at 9:59 AM, James Hartley jjhart...@gmail.com wrote:
On Wed, Apr 17, 2013 at 6:20 AM, Lele Gaifax l...@metapensiero.it wrote:
James Hartley jjhart...@gmail.com writes:
Is it possible to map Table instances back to classes defined through
declarative_base()?
...I assume you are asking whether you can map a view onto a
Python class using the declarative layer. If so, yes, SQLAlchemy does
not care about how the underlying table is implemented, it will issue
the same SQL in either cases.
Thanks for your reply. Any hints on how to tie a class inheriting from Base
to a Table? I have been unsuccessful in bridging the two.
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
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