OfMany and pivot data

[chris-ware]

Not sure if this is an idea, or a bug, or me simply missing something. The OfMany set of functions (oldestOfMany, latestOfMany and OfMany itself) are really useful for returning a single model as part of a relationship, however, this concept does connect to many-to-many relationships via a pivot table. With a standard relationship, you can instruct the relationship to load pivot data, as well as use pivot data as part of the relationship, however if you utilise a OfMany, it seems you cannot interact with pivot data. Take the following code as example:

    public function assets(): MorphToMany
    {
        return $this->morphToMany(config('assets.model'), 'assetable')
            ->withPivot('values')
            ->using(config('assets.pivot_model'));
    }

    protected function hasAssets(?string $name = null): MorphToMany
    {
        if ($name == null) {
            [, $caller] = debug_backtrace(DEBUG_BACKTRACE_IGNORE_ARGS, 2);

            $name = $caller['function'];
        }

        return $this->assets()
            ->wherePivot('field', $name)
            ->withPivotValue([
                'field' => $name,
            ]);
    }

In this example, we return a collection of assets, but in more instances than not, we actually are only expecting a single asset. This currently means that we need to check for the fact a collection has been returned and then run first() on it. In an ideal world, the OfMany mechanic would allow for the above behaviour of interacting with pivot data.

I will admit that as much as I'd love to do a PR for this, the required behaviour is far beyond my knowledge as a developer.