discourse/app/controllers/post_action_users_controller.rb

require_dependency 'discourse'

class PostActionUsersController < ApplicationController
  def index
    params.require(:post_action_type_id)
    params.require(:id)
    post_action_type_id = params[:post_action_type_id].to_i

    page = params[:page].to_i
    page_size = (params[:limit] || 200).to_i

    finder = Post.where(id: params[:id].to_i)
    finder = finder.with_deleted if guardian.is_staff?

    post = finder.first
    guardian.ensure_can_see!(post)

    post_actions = post.post_actions.where(post_action_type_id: post_action_type_id)
      .includes(:user)
      .offset(page * page_size)
      .order('post_actions.created_at asc')
      .limit(page_size)

    if !guardian.can_see_post_actors?(post.topic, post_action_type_id)
      if !current_user
        raise Discourse::InvalidAccess
      end
      post_actions = post_actions.where(user_id: current_user.id)
    end

    action_type = PostActionType.types.key(post_action_type_id)
    total_count = post["#{action_type}_count"]

    data = { post_action_users: serialize_data(post_actions.to_a, PostActionUserSerializer) }

    if total_count > page_size
      data[:total_rows_post_action_users] = total_count
    end

    render_json_dump(data)
  end
end