On Mon, Oct 9, 2017 at 3:57 PM, Colton Allen <[email protected]> wrote:
> I'm trying to execute a fairly simple UPDATE query.
>
> query = update(Model).where(Model.id.in_(list_of_ids)).values(x=1)
>
> I know of two methods to execute it. One using the session and the other
> using the engine. However, depending on which I use, the results I get are
> very different.
>
> db.session.execute(query) # works in test suite but not live.
> db.engine.connect().execute(query) # works live but not in test suite.
>
> I'm trying to understand why this would be the case. I believe either my
> test suite of my implementation of sqlalchemy is broken. I was wondering if
> you had any tips.
well the session version won't be committed unless you call
session.commit(). so...it seems like your test suite is probably
looking at the data uncommitted, which is fine, but for live you'd
want to make sure data is commited.
I guess in the opposite case, your test suite which relies upon the
data being rolled back for teardown doesn't occur when you use
engine.connect() because that makes its own transaction that is
autocommitting.
>
> Test Suite:
>
> def setUp(self):
> """Create app test client."""
> self.app = app
> self.app_context = self.app.app_context()
> self.app_context.push()
> self.client = self.app.test_client()
>
> self.transaction = connection.begin()
> db.session = scoped_session(
> sessionmaker(bind=connection, query_cls=db.query_class))
> db.session.begin_nested()
>
> @event.listens_for(db.session, "after_transaction_end")
> def restart_savepoint(session, transaction):
> if transaction.nested and not transaction._parent.nested:
> session.expire_all()
> session.begin_nested()
>
> # this is a cleanup function rather than a teardown function in case
> # the db gets into a bad state and setup fails, in which case we still
> # want the drop_all to be called
> self.addCleanup(self.cleanup)
>
> def cleanup(self):
> """Tear down database."""
> db.session.close()
> self.transaction.rollback()
> self.app_context.pop()
>
> @classmethod
> def setUpClass(cls):
> """Create the database."""
> global app, engine, connection
>
> app = cls._create_app()
> engine = db.engine
> connection = engine.connect()
>
> @classmethod
> def tearDownClass(cls):
> """Destroy the database."""
> connection.close()
> engine.dispose()
>
>
> Session construction when live:
>
> @property
> def engine(self):
> """Return an engine instance."""
> if not self._engine:
> database_uri = self.app.config.get('SQLALCHEMY_DATABASE_URI')
> self._engine = sqlalchemy.create_engine(database_uri)
> return self._engine
>
> @property
> def session(self):
> """Return database session."""
> if not self._session:
> factory = sqlalchemy.orm.sessionmaker(
> bind=self.engine, query_cls=self.query_class)
> self._session = sqlalchemy.orm.scoped_session(
> factory, scopefunc=_app_ctx_stack.__ident_func__)
> return self._session()
>
>
> --
> SQLAlchemy -
> The Python SQL Toolkit and Object Relational Mapper
>
> http://www.sqlalchemy.org/
>
> To post example code, please provide an MCVE: Minimal, Complete, and
> Verifiable Example. See http://stackoverflow.com/help/mcve for a full
> description.
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--
SQLAlchemy -
The Python SQL Toolkit and Object Relational Mapper
http://www.sqlalchemy.org/
To post example code, please provide an MCVE: Minimal, Complete, and Verifiable
Example. See http://stackoverflow.com/help/mcve for a full description.
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