Is there any way to get all roots for given collection?

[timurkhafizov]

I mean if I have some Category relation then I want to call something like roots on this collection and get roots only for given categories not the all root categories.

I tried to create custom class method but had no luck:

def self.tree_parents
  base_realtion = Category.none
  root_category_ids = []

  all.each do |category|
    if category.root?
      root_category_ids = []
    else
      base_relation = base_relation.merge(category.self_and_ancestors.where(_ct.parent_column_name.to_sym => nil))
    end
  end

  base_relation.merge(Category.where(id: root_category_ids))
end

I would appreciate any help.
Thank you!

[timurkhafizov]

Closing it right now. I have managed logic mistake in my code and going to fix it