How to display name instead of user_id in a datatable in Rails

everybody... For a couple of days I have encountered a problem in my application and that is giving me a lot to think about: I have a data table called "Devices" that contains a reference to "Users", in my data table I am bringing back the "user_id" but I want to take that data in the backend and show the "username" in the frontend. How can I get the expected result? I would greatly appreciate with any help you can give me

in the "user" column the "user_id" is hosted columns

in my index.html.haml:

.table__wrapper
    = form_tag edit_multiple_devices_path, method: :get do
      %table{:role => 'datatable'}
        %thead
          %tr
            %th
            %th.abbr{:title => "aidi"} Id
            %th.abbr{:title => "imei"} Imei
            %th.abbr{:title => "brand"} Marca
            %th.abbr{:title => "model"} Modelo
            %th.abbr{:title => "prov"} Proovedor
            %th.abbr{:title => "fac"} Factura
            %th.abbr{:title => "din"} Entrada
            %th.abbr{:title => "sim"} Sim
            %th.abbr{:title => "iccid"} Iccid
            %th.abbr{:title => "status"} Status
            %th.abbr{:title => "user_id"} Usuario
            %th.abbr{:title => "client"} Cliente
            %th.abbr{:title => "dout"} Salida
            %th.abbr{:title => :use} Usado
            %th.abbr{:title => :old} Reutilizado
          %tbody
            - @devices.each do |device|
              %tr
                %td= check_box_tag "device_ids[]", device.id
                %td= device.aidi
                %td= device.imei
                %td= device.brand
                %td= device.model
                %td= device.prov
                %td= device.fac
                %td= device.din
                %td= device.sim
                %td= device.iccid
                %td= device.status
                %td= device.user_id
                %td= device.client
                %td= device.dout
                %td= device.use
                %td= device.old
      = submit_tag "Editar", class: "button is-primary is-rounded"

in my device.rb

class Device < ApplicationRecord
belongs_to :user
attr_accessible :aidi, :imei, :brand, :model, :prov, :fac, :din, :sim, :iccid, :status, :user_id, :client, :dout, :use, :old
end

in my user.rb

class User < ApplicationRecord
has_many :devices
end

thanks for the knowledge