Laravel Eloquent - Many to One Relation

I have Models: ArtObjects and Photos:

class Photo extends Model { protected $fillable = ['caption','description','alternative_text'];

public function artObject()
{
    return $this->belongsTo('App\ArtObject');

}

} class ArtObject extends Model {

/**
 * The attributes that are mass assignable.
 *
 * @var array
 */
protected $fillable = [

    'title',
    'description',
    'rating',
    'popularity',
    'type',
    'price'
];

public function photos()
{

    return $this->hasMany(ArtObjectPhoto::class);

}

}

Controllers:

ArtObject Controller:

public function store(ArtObjectUploadRequest $request) {

    $art_object = ArtObject::create(request(['title', 'description', 'rating', 'popularity', 'type', 'price']));

    $this->validate($request, [
        'title' => 'required',
        'description' => 'required'
    ]);

    foreach ($photo_ids = Input::get('photos') as $photo_id) {

        $photo = Photo::find($photo_id);

        /*

Problem is here - The user wants to attach the selected photos with the art-object, ........ Please advise, thanks in anticipation !!! */

    }

    //save the artobject to the database
    $art_object->save();

    //And redirect to the home page
    return redirect('/');

}

Problem: The user wants to attach the selected photos with the art-object. Note that the photos already exists in the db. I have tried options - save(), associate () but nothing helped. My understanding is once I find () the photo it should give me Photo object which I should be able to save () with $art_object. It wants me to new() and assign from DB and assign to the Photo object. But I don't think this is the right way of doing this. I believe this is not the best way of implementing the many-to-relation , then what is the best way saving this relation. Please advise, thanks in anticipation !!!

via Chebli Mohamed