On Sunday, December 18, 2011 2:07:40 PM UTC-8, Jonathan Vanasco wrote:
>
> ...
>
> 2. Have my models reflect the database. With some custom routines, I
> largely just had to pass in a string for the tablename and a sometimes
> primary key .
>
> I'm not sure how to do that under Pyramid ( I am using the Akhet
> scaffold ).
>
I'm using database reflection quite happily in a project. I started from a
pyramid_routesalchemy scaffold, so I'm not sure how applicable the
following is to an Akhet project, but I suspect there is some common ground.
In my models.py module I created a ReflectedTable class to handle the
reflection and mapper setup, a bunch of class stubs that inherit from it,
and a map_tables function that gets called in initialize_sql() to make
everything happen:
from sqlalchemy import Table
from sqlalchemy import MetaData
from sqlalchemy.orm import mapper
from sqlalchemy.orm import scoped_session
from sqlalchemy.orm import sessionmaker
from zope.sqlalchemy import ZopeTransactionExtension
DBSession =
scoped_session(sessionmaker(extension=ZopeTransactionExtension()))
metadata = MetaData()
class ReflectedTable(object):
"""Base class for database objects that are mapped to tables by
reflection.
"""
@classmethod
def map_by_reflection(cls, table_name):
"""Map the specified database table to the object by
reflection.
"""
table = Table(table_name, metadata, autoload=True)
mapper(cls, table)
class SomeTable(ReflectedTable): pass
class SomeOtherTable(ReflectedTable): pass
def map_tables():
objs_and_tables = [
(SomeTable, 'some_table_name'),
(SomeOtherTable, 'some_other_table_name'),
]
for obj, table_name in objs_and_tables:
obj.map_by_reflection(table_name)
def initialize_sql(engine):
DBSession.configure(bind=engine)
metadata.bind = engine
map_tables()
initialize_sql gets called in __init__.main() so the reflection is all done
during app startup. I suspect that's where you would want to do your
multiple engine setup too, but I've never tried that.
Hope that helps...
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