foreign_key_fail.py

pg_url = 'postgres://{user}:{pw}@{host}/{db}'
engine = create_engine(pg_url)
metadata = MetaData(bind=ops.engine)

metadata.reflect(schema='tbl_schema', only=['tbl_name'])
fk_column = metadata.tables['tbl_schema.tbl_name'].columns['tbl_column']
fk = ForeignKey(fk_column)

# list of columns that should have the foreign key
fk_list = [...]

# list of column objects that are not yet associated with a table
for col in columns:
    if col.name in fk_list:
        col.foreign_keys.add(fk)
        print col.foreign_keys
        # output shows that foreign key has been added

table = Table(
    table_name,
    metadata,
    *columns
)
table.create()

print table.foreign_keys
# output shows table has no foreign keys