Bug #105349 for DBIx-Class: Add check to see if relationship has loaded

<URL: https://rt.cpan.org/Ticket/Display.html?id=105349 >

On 06/18/2015 10:17 PM, Jon Rubin via RT wrote:

> Thu Jun 18 16:17:35 2015: Request 105349 was acted upon.
> Transaction: Ticket created by jon.rubin@grantstreet.com
>         Queue: DBIx-Class
>       Subject: Add check to see if relationship has loaded
>     Broken in: (no value)
>      Severity: (no value)
>         Owner: Nobody
>    Requestors: jon.rubin@grantstreet.com
>        Status: new
>   Ticket <URL: https://rt.cpan.org/Ticket/Display.html?id=105349 >

>
>
> Hi,
>
> I recently came across a case where I wanted to determine if a relationship
> on a row was already loaded before accessing it. Frequently, the relation
> would be a circular reference, and there was no reason to hit the database
> if this was the case. However, if the relationship *was* already loaded,
> then I wanted to return the loaded copy (eg. to preserve prefetch
> functionality).
>
> Maybe code will explain better:
>
> sub get_original_foo
> {
>      my ($self) = @_;
>
>      if ( $self->get_column('foo_id') ==
> $self->get_column('original_foo_id') ) {
>          # If we've already prefetched the original_foo, return that.
>          # Otherwise we'll lose out on any benefits gained by prefetching
> other
>          # DB objects through original_foo
>
>          # Ideally would check $self->has_relationship_loaded('original_foo')
>
>
>          return $self unless exists $self->{_relationship_data}{original_foo}
>                           || exists $self->{_inflated_column}{original_foo};
>      }
>      return $self->original_foo;
> }
>
>
> I've given the fix a go in the attached patch, written for
> DBIx-Class-Row-0.082810
> (it includes documentation and test updates).
>
> FWIW, I'm running perl v5.10.1, on both Mac and Linux.
>
> Let me know if there's an existing solution I've missed. Otherwise, if this
> makes sense, I can submit the patch in git.
>

Hi!

Thank you for the contribution. This was an already-requested feature
with a patch similar to your written and living under the branch
'people/abraxxa/has_relationship_loaded'. The reason it never merged was
because at the time several corner cases were encountered that didn't
have an easy solution, and the gneral understanding of the interactions
with IC were poorly understood by pretty much all maintainers (me included).

With that said - it is probably time to revisit this work. I will try my
best to do so in the next week, and will see whether yours or abraxxa's
work can be incorporated in a better manner. Please do bug me if you do
not hear anything by the end of the month - there is currently another
project that keeps distracting me, so I may end up dropping this on the
floor (again).

Thanks!

<URL: https://rt.cpan.org/Ticket/Display.html?id=105349 >

On 07/09/2015 03:13 PM, Jon Rubin via RT wrote:

>         Queue: DBIx-Class
>   Ticket <URL: https://rt.cpan.org/Ticket/Display.html?id=105349 >

>

> Hi Peter!
>
> Just checking in on the status of this - you told me to bother you if I
> hadn't heard anything by the end of June :)
>
>

Unfortunately there are no news yet, as I am slowly slogging through the
rather ossified relationship system :( Please re-poke me at the end of
this month, as I am likely to not have anything before then.

Sorry once again - work is progressing, just very very slowly.