On 10/13/15 7:16 AM, Don O'Hara wrote:
> I'm looking for advice on best SA coding practices to accomplish:
>
> 1. Use bind keys
I'm not familiar with that, I see you using something called
__bind_key__ and SQLALCHEMY_BINDS. These are not constructs that are
part of SQLAlchemy; if this is a third-party package of some kind, I'd
ask them for help.
> 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:
>
> |
> _inconfig.__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:
>
> |
> classAccountCodeNamespace(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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