[8.x] Allow custom relationship types

[caseydwyer]

This PR adds functionality to the Relationships class, allowing for registration of custom save-methods. The core Runway features provide 95% of what's needed for custom relationships, but an error is thrown when using a third-party class since the only match cases are native HasMany and BelongsToMany eloquent relationships. We're just adding a default/fallback, to provide devs with an option for registering their own save callback.

A good example use-case would be the relationship classes found in the Eloquent JSON Relations package, where a belongs-to-many equivalent can exist in a JSON column. Here's how this could be used, from within a service provider:

use Staudenmeir\EloquentJsonRelations\Relations\BelongsToJson;

Relationships::registerCustomSaveMethod(
    BelongsToJson::class,
    fn ($field, $relationship, $values) => $relationship->sync($values)->save()
);

And then the corresponding field from the resource's blueprint:

-
  handle: hiring_manager_roles
  field:
    mode: select
    resource: staff_role
    relationship_name: hiringManagerRoles
    type: has_many
    display: 'Hiring Manager Roles'

Obviously an unsolicited feature request, but would be a big improvement on super-dynamic projects that leverage JSON columns in multiple places. Please let me know if there's anything I can do to improve this (general updates, along with tests, doc updates, etc.) and I'll make it happen. Thanks for considering this!

[duncanmcclean]

Good idea!

Although, can we use a hook instead of our own saveCustomRelationship method?

[caseydwyer]

can we use a hook instead of our own saveCustomRelationship method?

Ooh, yeah—good call on that! Tbh, I did not know you could use hooks like that, so let me know if this isn't what you had in mind. This updated approach of course requires different usage, something like this I think:

Relationships::hook('saveCustomRelationship', function ($payload, $next) {
    [
        'relationship' => $relationship,
        'values' => $values,
    ] = $payload;

    if(get_class($relationship) === BelongsToJson::class){
        $relationship->sync($values)->save();
    }

    return $next($payload);
});

[duncanmcclean]

That's perfect! I'll review this properly next week. 🙂

[duncanmcclean]

Looks good - thanks!

[github-actions]

Released as part of v8.8.0.