Using SQLAlchemy 0.9.7 against a PostgreSQL 9.2 database.
with e as an Engine:
i = 1
with e.begin() as conn:
x = conn.execute('select * from test01')
print x.fetchall()
with conn.contextual_connect() as conn2:
with conn2.begin():
i += 1
conn2.execute('insert into marius.test01 values (%s)' % str(i))
x = conn2.execute('select * from test01')
print x.fetchall()
x = conn.execute('select * from test01')
print x.fetchall()
raise Exception("HELLO")
This will actually commit a row to the table test, rather than commit
nothing.
Should the transaction not be carried over to the branched connection?
This is not PostgreSQL specific.
Something like this solves this potential issue:
class Connection(sqlalchemy.engine.Connectable):
"""Override of :class:`sqlalchemy.engine.Connection` to allow allow
"nested" connections (non-forking).
This is achieved by using a stack increment decrement.
"""
def __init__(self, engine, connection=None, close_with_result=False,
_branch=False, _execution_options=None,
_dispatch=None, _has_events=None, transaction=None):
...
self.__transaction = transaction
...
def _branch(self):
"""Return a new Connection which references this Connection's
engine and connection; but does not have close_with_result
enabled,
and also whose close() method does nothing.
This is used to execute "sub" statements within a single
execution,
usually an INSERT statement.
"""
return self.engine._connection_cls(
self.engine,
self._Connection__connection,
_branch=True,
_has_events=self._has_events,
_dispatch=self.dispatch,
transaction=self.__transaction)
What is the standard way to deal with this case? Subclassing Connection to
implement this?
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