Laravel 5.6 – Pass additional parameters to API Resource?

The following approach worked for me:

UserResource

class UserResource extends Resource{

    protected $foo;

    public function foo($value){
        $this->foo = $value;
        return $this;
    }

    public function toArray($request){
        return [
            'id' => $this->id,
            'name' => $this->name,
            'foo' => $this->foo,
         ];
    }

    public static function collection($resource){
        return new UserResourceCollection($resource);
    }
}

UserCollection

class UserResourceCollection extends ResourceCollection{

    protected $foo;

    public function foo($value){
        $this->foo = $value;
        return $this;
    }

    public function toArray($request){
        return $this->collection->map(function(UserResource $resource) use($request){
            return $resource->foo($this->foo)->toArray($request);
    })->all();

        // or use HigherOrderCollectionProxy
        // return $this->collection->each->foo($this->foo)->map->toArray($request)->all()

        // or simple
        // $this->collection->each->foo($this->foo);
        // return parent::toArray($request);
    }
}

Different ways to pass the additional parameter

(new UserResource($user))->foo('bar');
(new UserResourceCollection($user))->foo('bar');

UserResource::make($user)->foo('bar');
UserResourceCollection::make($users)->foo('bar');
UserResource::collection($users)->foo('bar');