CODEWITHSUNDEEP
django
Alexey Ruzin
Alexey Ruzin

Reputation: 1027

Django: how to use two simultaneous connections to a single Database?

Let we have the code:

def some_function():
    with transaction.atomic():
        # some code which writes to DB

        try:
            call_method_which_may_raise_exception()
        except KnownException as e:
            save_some_data_about_exception_to_database(e)
            raise

        # other code which writes to DB

The problem is when I re-raise the exception, my 'SOME DATA' will be lost too, because it's made within same transaction. Is there a context or something to execute code within SEPARATE transaction/connection?

There is a point, that the code has bad architect. In a normal flow there should not be a neccessity to save_some_data...

As proposed solution they said:

def some_function():
    exception_to_save = None
    try:
        with transaction.atomic():
            # some code which writes to DB

            try:
                call_method_which_may_raise_exception()
            except KnownException as e:
                exception_to_save = e
                raise

            # other code which writes to DB
    except Exception as e:
        if exception_to_save:
            save_some_data_about_exception_to_database(exception_to_save)
        raise

But dirty code gets once more dirty.

I'd prefer if it was something like:

def some_function():
    with transaction.atomic():
        # some code which writes to DB

        try:
            call_method_which_may_raise_exception()
        except KnownException as e:
            with transaction.separate_connection():  
                save_some_data_about_exception_to_database(e)
            raise

        # other code which writes to DB

Any ideas are welcome!

Upvotes: 3

Views: 174

Answers (1)

Raz
Raz

Reputation: 7923

I don't see any reason to use separate connections. Isn't it enough just to use a lower level API?

def some_function():
    transaction.set_autocommit(False)
    try:
        call_method_which_may_raise_exception()
    except KnownException as e:
        transaction.rollback()
        save_some_data_about_exception_to_database(e)
        raise
    finally:
        transaction.commit()
        transaction.set_autocommit(True)

Upvotes: 1

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