Method _prepare_impl

lib/sqlalchemy/orm/session.py:1289–1320

(self)

        (SessionTransactionState.ACTIVE,), SessionTransactionState.PREPARED
    )
    def _prepare_impl(self) -> None:
        if self._parent is None or self.nested:
            self.session.dispatch.before_commit(self.session)

        stx = self.session._transaction
        assert stx is not None
        if stx is not self:
            for subtransaction in stx._iterate_self_and_parents(upto=self):
                subtransaction.commit()

        if not self.session._flushing:
            for _flush_guard in range(100):
                if self.session._is_clean():
                    break
                self.session.flush()
            else:
                raise exc.FlushError(
                    "Over 100 subsequent flushes have occurred within "
                    "session.commit() - is an after_flush() hook "
                    "creating new objects?"
                )

        if self._parent is None and self.session.twophase:
            try:
                for t in set(self._connections.values()):
                    cast("TwoPhaseTransaction", t[1]).prepare()
            except:
                with util.safe_reraise():
                    with self._expect_state(SessionTransactionState.CLOSED):
                        self.rollback()

        self._state = SessionTransactionState.PREPARED

    @_StateChange.declare_states(
        (SessionTransactionState.ACTIVE, SessionTransactionState.PREPARED),