route_key(record_or_class)
Class Public methods
Returns string to use while generating route names. It differs for
namespaced models regarding whether it's inside isolated engine.
# For isolated engine:
ActiveModel::Naming.route_key(Blog::Post) # => "posts"
# For shared engine:
ActiveModel::Naming.route_key(Blog::Post) # => "blog_posts"
The route key also considers if the noun is uncountable and, in such cases,
automatically appends _index.