app/models/user.rb
require_relative 'concerns/exportable'
class User < ActiveRecord::Base
has_many :posts
has_many :users_in_posts, dependent: :destroy
has_many :tagged_in_posts, through: :users_in_posts, source: :post
include Exportable
add_export prefix: 'user',
export_fields: %i[ id instagram_id nick_name ]
end