No worries and thanks for the suggestions/advice so far.
Tbh I tried the mixin approach first as described in the docs but had
problems when trying to query anything on the 2nd class.
This is a boiled down version of what I tried:
import sqlalchemy as sa
from sqlalchemy.orm import sessionmaker, relationship
from sqlalchemy.ext.declarative import declarative_base, DeferredReflection
e = sa.create_engine("sqlite://", echo=True)
e.execute("""
create table country (
country_id integer primary key
)
""")
e.execute("""
create table user (
user_id integer primary key
)
""")
Base = declarative_base(cls=DeferredReflection)
Base2 = declarative_base(cls=DeferredReflection)
# exists in PROD & DEV
class Country(Base):
__tablename__ = 'country'
# exists only in PROD
class User(Base2):
__tablename__ = 'user'
country_id = sa.Column(sa.Integer,
sa.ForeignKey('country.country_id'))
country = relationship("Country", uselist=False)
class MyModel(object):
def __init__(self, env):
self._engine = e
# Base.metadata.bind = self._engine - binding at this level didn't
help :(
if env == "DEV":
Base2.metadata.bind = self._engine
Base2.prepare(self._engine)
Base.metadata.bind = self._engine
Base.prepare(self._engine)
def create_session_maker(self):
return sessionmaker(bind=self._engine)
# This code is run in another module.
mymodel = MyModel("PROD")
Session = mymodel.create_session_maker()
session = Session()
session.query(Country).count()
session.query(User).count()
And the result:
2016-09-07 10:03:43,889 INFO sqlalchemy.engine.base.Engine SELECT CAST('test
plain returns' AS VARCHAR(60)) AS anon_1
2016-09-07 10:03:43,891 INFO sqlalchemy.engine.base.Engine ()
2016-09-07 10:03:43,892 INFO sqlalchemy.engine.base.Engine SELECT CAST('test
unicode returns' AS VARCHAR(60)) AS anon_1
2016-09-07 10:03:43,893 INFO sqlalchemy.engine.base.Engine ()
2016-09-07 10:03:43,894 INFO sqlalchemy.engine.base.Engine
create table country (
country_id integer primary key
)
2016-09-07 10:03:43,895 INFO sqlalchemy.engine.base.Engine ()
2016-09-07 10:03:43,896 INFO sqlalchemy.engine.base.Engine COMMIT
2016-09-07 10:03:43,897 INFO sqlalchemy.engine.base.Engine
create table user (
user_id integer primary key
)
2016-09-07 10:03:43,897 INFO sqlalchemy.engine.base.Engine ()
2016-09-07 10:03:43,898 INFO sqlalchemy.engine.base.Engine COMMIT
2016-09-07 10:03:43,902 INFO sqlalchemy.engine.base.Engine PRAGMA
table_info("country")
2016-09-07 10:03:43,903 INFO sqlalchemy.engine.base.Engine ()
2016-09-07 10:03:43,904 INFO sqlalchemy.engine.base.Engine PRAGMA
foreign_key_list("country")
2016-09-07 10:03:43,905 INFO sqlalchemy.engine.base.Engine ()
2016-09-07 10:03:43,906 INFO sqlalchemy.engine.base.Engine PRAGMA
index_list("country")
2016-09-07 10:03:43,906 INFO sqlalchemy.engine.base.Engine ()
2016-09-07 10:03:43,910 INFO sqlalchemy.engine.base.Engine BEGIN (implicit)
2016-09-07 10:03:43,912 INFO sqlalchemy.engine.base.Engine SELECT count(*) AS
count_1
FROM (SELECT country.country_id AS country_country_id
FROM country) AS anon_1
2016-09-07 10:03:43,912 INFO sqlalchemy.engine.base.Engine ()
InvalidRequestError: SQL expression, column, or mapped entity expected - got
'<class '__main__.User'>'
I'm pretty sure I also tried the abstract approach with similar results.
Perhaps I'm binding incorrectly?
On Tuesday, 6 September 2016 18:37:14 UTC+1, Mike Bayer wrote:
>
>
>
> On 09/06/2016 12:50 PM, bsdz wrote:
> > Thanks for your reply.
> >
> > I think you misread my code. The method "remove" does exist. It's a
> method of MetaData and not tables. See
> http://docs.sqlalchemy.org/en/rel_1_0/core/metadata.html#sqlalchemy.schema.MetaData.
>
>
>
> I did misread.
>
> >
> > I'm not sure about automap. I'm not keen on reflecting all the tables in
> my database and prefer fine grained control.
>
>
> metadata.reflect() allows for limiting the set of tables using "only":
>
>
> http://docs.sqlalchemy.org/en/latest/core/metadata.html?highlight=metadata.reflect#sqlalchemy.schema.MetaData.reflect.params.only
>
>
>
> > Furthermore, I would like to keep deferred reflection as it allows
> one to choose an environment before binding to an engine.
>
> automap and deferred reflection kind of do the same thing, it's just the
> former does a lot more.
>
> in any case, launching prepare() from targeted mixins w/
> DeferredReflection should work if I'm reading the code correctly (which
> we've already demonstrated is challenging me today).
>
>
>
>
>
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