a11yist/app/models/checklist_entry.rb

class ChecklistEntry < ApplicationRecord
  belongs_to :checklist
  belongs_to :check

  before_validation :set_position
  after_validation :normalize_positions

  def set_position
    self.position ||= checklist.checklist_entries.maximum(:position).to_i + 1
  end

  def normalize_positions
    checklist.checklist_entries.where.not(id:).find_by(position:)&.update_attribute(:position, position_was)
    # checklist.checklist_entries.order(:position).each_with_index do |entry, index|
    #   entry.update_column(:position, index + 1) if entry.position != index + 1
    # end
  end
end