/**
 * Set the Slug attribute and add counter if not unique.
 * This function will check if the current model's slug is unique and update
 * if with a counter at the end of the slug (such as -2) if there already exists.
 * For example, if we're saving a page called "About us" with the slug
 * "about-us", but for some reason you already have a page with the slug
 * "about-us" this new page would then be set to have the slug
 * "about-us-2" instead.
 *
 * @param any $value This is the value passed to this setting function.
 *
 * @return void
 */
public function setSlugAttribute ($value) {
    $model = get_class($this);
    $attribute = 'slug';
    $default = 'full_name'; // which attribute from the model to pull if no slug set

    $empty = $model::all()->where($attribute,$value)->except($this->id)->isEmpty();
    if ($value != $this->slug || $this->slug == null || !$empty) {
        if ($value == null || empty($value)) {
            $value = str_slug($this->$default);
        } else {
            $value = str_slug($value);
        }

        if (!$empty) {
            $current = explode('-', $value);
            $countStart = 1;
            if (is_numeric(end($current))) {
                $countStart = end($current);
                $value = implode("-", array_splice($current, 0, -1));
            }
            $tempSlug = $value . '-'. $countStart;
            for ($i = $countStart; !$model::all()->where($attribute,$tempSlug)->except($this->id)->isEmpty(); $i++) {
                $tempSlug = $value . '-' . $i;
            }
            $value = $tempSlug;
        }

        $this->attributes[$attribute] = $value;
    }
}