Hi,
I have a models.py file where I'd like to define all the table classes and
then interact with them from my main module file (desktop app). I am
connecting to Postgres 9.5 and have attached another Postgres database on
the same server (localhost) with postgres_fdw. It all appears to be
working well, print(insp.get_foreign_table_names()) shows the attached
tables. This is with Python 3.5.2 on Windows 7.
I am using DeferredReflection so I don't have to have the engine setup in
the model file and am connecting to one of the foreign tables:
BaseDef = declarative_base(cls=DeferredReflection)
class TestTable(BaseDef):
__tablename__ = 'test_table'
and get the error when I run BaseDef.prepare(engine):
sqlalchemy.exc.ArgumentError: Mapper Mapper|TestTable|test_table could not
assemble any primary key columns for mapped table 'test_table'
I tried:
class TestTable(BaseDef):
__tablename__ = 'test_table'
Column('test_id', Integer, primary_key=True) # no effect
and
__mapper_args__ = {
'primary_key': (test_table.c.test_id, )} # attribute error on
test_id
Can I use DeferredReflection and still define the primary key column?
Also, any issue with defining some of the classes using a normal Base =
declarative_base() and some with deferred? I'm using the normal Base with
classes where the full table definition is in the model file. I'm just
starting to work with SQLAlchemy and Postgres after mostly working with
SQLite (and I'm a hardware guy).
Thanks,
Eric
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