I'm looking for advice on best SA coding practices to accomplish:
1. Use bind keys
2. Add user-defined tags to tables, to allow iterating through the metadata
later to find tables with those tags.
3. Use base table classes for common attributes and methods
Is there a chance that class member names will get mangled in derived
classes,
and cause problems somewhere downstream? The code works now, but when I
remove one of the
base classes, and code the metadata directly in the table class things
break.
I'd like to get a better understanding of how it all fits, and make sure
I'm setting things up correctly.
Thanks,
Don
My code:
*in config.*
*py*
SQLALCHEMY_BINDS = {
'api': 'postgresql+psycopg2://oharad:dino@localhost:5432/dev_api_02',
'person_indexes':
'postgresql+psycopg2://oharad:dino@localhost:5432/dev_person_ix_01',
'analysis_result':
'postgresql+psycopg2://oharad:dino@localhost:5432/dev_analysis_res_01'
}
*in models/__init__.py*
ACCOUNT_SCHEMA_NAMESPACE = 'account'
class BaseAppTable(db.Model):
__abstract__ = True
def to_json(self):
json = {c.name: str(getattr(self, c.name)) or '' for c in
self.__table__.columns}
return json
*in models/account.py*
from models import BaseAppTable, db, ACCOUNT_SCHEMA_NAMESPACE
_BASE_TABLE_ARGS = {'info': {'table_namespace': ACCOUNT_SCHEMA_NAMESPACE}}
class BaseAccountTable(object):
__bind_key__ = 'api'
__table_args__ = _BASE_TABLE_ARGS
class Account(BaseAppTable, BaseAccountTable):
__tablename__ = "account"
#
# need to explicitly code __table_args__ here to use 'tuple, dict'
syntax
__table_args__ = (UniqueConstraint('name', 'company_id',
name='account_uq_ix1'),
_BASE_TABLE_ARGS)
account_id = db.Column(db.Integer, primary_key=True)
name = db.Column(db.String(length=50), nullable=False)
company_id = db.Column(db.Integer,
db.ForeignKey('global.company.company_id'), nullable=False)
class RoleGroup(BaseAppTable, BaseAccountTable):
__tablename__ = "role_group"
role_group_id = db.Column(UUID, primary_key=True)
type_code = db.Column(db.SmallInteger, nullable=False)
name = db.Column(db.String(length=100), nullable=False, unique=True)
This code works fine, but I'm worried something might break due to name
mangling.
When I change the code to avoid base classes, I get an error:
class AccountCodeNamespace(BaseAppTable):
__tablename__ = "account_code_namespace"
__table_args__ = _BASE_TABLE_ARGS
__bind_key__ = 'api'
* # AssertionError: Bind 'api' is not specified. Set it in the
SQLALCHEMY_BINDS configuration variable*
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