/**
* Parse a transformer class and set relations.
*
* @param \Flugg\Responder\Transformer|callable $transformer
* @param \Illuminate\Database\ELoquent\Model $model
* @return \Flugg\Responder\Transformer|callable
* @throws \InvalidTransformerException
*/
protected function parseTransformer($transformer, Model $model)
{
if ($transformer instanceof Transformer) {
$relations = $transformer->allRelationsAllowed() ? $this->resolveRelations($model) : $transformer->getRelations();
$transformer = $transformer->setRelations($relations);
} elseif (!is_callable($transformer)) {
throw new InvalidTransformerException($model);
}
return $transformer;
}