public function toArray()
    {
        $relations = [];
        $arrayableRelations = [];

        // include any relations exposed by default
       foreach ($this->exposedRelations as $relation) {
            // skip loading a relation if it is from a method
            if (in_array($relation, $this->relationsFromMethod)) {
                // if the relation hasnt been loaded, then load it
                if (!isset($this->$relation)) {
                    $this->$relation = $this->$relation();
                }

                $arrayableRelations[$relation] = $this->$relation;
                continue;
            }

            $this->load($relation);
        }

        // fetch the relations that can be represented as an array
        $arrayableRelations = array_merge($this->getArrayableRelations(), $arrayableRelations);

        // add the relations to the linked array
        foreach ($arrayableRelations as $relation => $value) {
            if (in_array($relation, $this->hidden)) {
                continue;
            }

            if ($value instanceof Pivot) {
                continue;
            }

            if ($value instanceof BaseModel) {
                $relations[$relation] = array('linkage' => array('id' => (string)$value->getKey(), 'type' => $value->getResourceType()));
            } elseif ($value instanceof Collection) {
                $relation = \str_plural($relation);
                $items = ['linkage' => []];
                foreach ($value as $item) {
                    $items['linkage'][] = array('id' => (string)$item->getKey(), 'type' => $item->getResourceType());
                }
                $relations[$relation] = $items;
            }

            // remove models / collections that we loaded from a method
            if (in_array($relation, $this->relationsFromMethod)) {
                unset($this->$relation);
            }
        }

        //add type parameter
        $model_attributes = $this->attributesToArray();
        unset($model_attributes[$this->primaryKey]);

        $attributes = [
            'id'         => (string)$this->getKey(),
            'type'       => $this->getResourceType(),
            'attributes' => $model_attributes
        ];

        if (! count($relations)) {
            return $attributes;
        }

        return array_merge(
            $attributes,
            [ 'links' => $relations ]
        );
    }