获取laravel5模型中的所有关系名称

I have model include of several relation for example like this:

public function NewsCategory()
{ 
   return $this->belongsTo("News\Model\NewsCategory");
}
public function NewsImage()
{ 
   return $this->belongsTo("News\Model\NewsImage");
}
public function NewsTag()
{ 
   return $this->belongsTo("News\Model\NewsTag");
}

and relations create dynamically.
How can I get all this class name? In this example I want
NewsCategory,NewsImage,NewsTag

one approach is to as follows :

$results = ModelClass::where(x,y)->with(['NewsCategory','NewsImage','NewsTag'])->first();

then you can use getRelations();

$relationshipKeys = array_keys($results->getRelations());

$model_specific_method_name_array = array_diff(get_class_methods(<YourMOdel>), get_class_methods(<AnotherDummyEloquentModelWithoutAnyMethods>));

Then remove other known methods on your model from array.