Method __enter__

django/db/transaction.py:193–233

(self)

        self._from_testcase = False

    def __enter__(self):
        connection = get_connection(self.using)

        if (
            self.durable
            and connection.atomic_blocks
            and not connection.atomic_blocks[-1]._from_testcase
        ):
            raise RuntimeError(
                "A durable atomic block cannot be nested within another "
                "atomic block."
            )
        if not connection.in_atomic_block:
            # Reset state when entering an outermost atomic block.
            connection.commit_on_exit = True
            connection.needs_rollback = False
            if not connection.get_autocommit():
                # Pretend we're already in an atomic block to bypass the code
                # that disables autocommit to enter a transaction, and make a
                # note to deal with this case in __exit__.
                connection.in_atomic_block = True
                connection.commit_on_exit = False

        if connection.in_atomic_block:
            # We're already in a transaction; create a savepoint, unless we
            # were told not to or we're already waiting for a rollback. The
            # second condition avoids creating useless savepoints and prevents
            # overwriting needs_rollback until the rollback is performed.
            if self.savepoint and not connection.needs_rollback:
                sid = connection.savepoint()
                connection.savepoint_ids.append(sid)
            else:
                connection.savepoint_ids.append(None)
        else:
            connection.set_autocommit(
                False, force_begin_transaction_with_broken_autocommit=True
            )
            connection.in_atomic_block = True

        if connection.in_atomic_block:
            connection.atomic_blocks.append(self)

    def __exit__(self, exc_type, exc_value, traceback):
        connection = get_connection(self.using)