Hello. We are currently setting up the association.

We are building a 1: many relationship with worker: lists and would like to display it if there is worker.user_name in lists/show.

But if workers do not exist

undefined method ʻuser_name'for nil: NilClass

Error has occurred and cannot be resolved.

References: worker is specified, and the following settings are also made in model.

belongs_to: worker

has_many: lists

def show
    @list = List.find (params [: id])
    @q = List.ransack (params [: q])
    @lists = @ q.result
    @prev_list = @ lists.where ("lists.id<?", @ List.id) .last
    @next_list = @ lists.where ("lists.id>?", @ List.id) .first
  end
private
 def list_params
  params.require (: list) .permit (
    : company, # company name
  )&.merge (worker: current_worker)
 end

 = @ list.worker.user_name

Is there a mistake in the above program?
I look forward to working with you.