def forming_position
  nodes = params[:nodes_list].permit!
  nodes.each do |node|
    recursive_sorting node
  end
end

def recursive_sorting(node, parent = nil)
  position = node[0]
  value = node[1]
  ......
end

params[:nodes_list]
=> <ActionController::Parameters {"1"=><ActionController::Parameters {"id"=>"3"} permitted: true>, "2"=><ActionController::Parameters {"id"=>"2"} permitted: true>, "3"=><ActionController::Parameters {"id"=>"1"} permitted: true>} permitted: true>

nodes
=> <ActionController::Parameters {"1"=><ActionController::Parameters {"id"=>"3"} permitted: true>, "2"=><ActionController::Parameters {"id"=>"2"} permitted: true>, "3"=><ActionController::Parameters {"id"=>"1"} permitted: true>} permitted: true>
nodes == params[:nodes_list]
=> true

node
=> "1"

nodes.first
=> ["1", <ActionController::Parameters {"id"=>"3"} permitted: true>]