[Dbix-class] RecursiveUpdate and many to many

[Oliver Gorwits]

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Zbigniew Lukasiak wrote:
> I would like to include your critisizm of the support for many to
> many in RecursiveUpdate in it's documentation.  Tell me if I get
> it right. What I remember is two points:
> 
> 1. That I rely on the fact that
> 
> if($object->can($name) and 
> !$object->result_source->has_relationship($name) and 
> $object->can( 'set_' . $name ) )
> 
> then $name must be a many to many pseudo relation. 

So my version of the heuristic goes like this:

# start with a has_many relation.
# check for related source having two belongs_to rels *only*,
# and one of them refers to ourselves,
# and at most one other col (id pk)
# then the *other* rel on the related source is the "target"

...if that doesn't match, then the link table probably isn't sane,
and the m2m code should be avoided.

I have some code to do this, and am pondering its fragility before
shipping in the next release of LFB's Metadata.pm.


Ideally, DBIC would instead populate the relationship_info details
after someone has set up __PACKAGE__->many_to_many(...). That would
avoid this guesswork.

regards,
oliver.
- --
Oliver Gorwits, Network and Telecommunications Group,
Oxford University Computing Services
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