Listing the names of associated models
You want ActiveRecord::Reflection::ClassMethods#reflect_on_all_associations
So it would be:
Article.reflect_on_all_associations
And you can pass in an optional parameter to narrow the search down, so:
Article.reflect_on_all_associations(:has_many)
Article.reflect_on_all_associations(:belongs_to)
Keep in mind that if you want the list of all the names of the models you can do something like:
Article.reflect_on_all_associations(:belongs_to).map(&:name)
This will return a list of all the model names that belong to Article.