Uploads folder is not generated

[dmunozvenegas]

I have carrierwave-datamapper installed in my project.

ruby 2.0.0
rails 3.1.11

generate uploader file

class ArchivoUploader < CarrierWave::Uploader::Base

storage :file

def store_dir
"uploads/#{model.class.to_s.underscore}/#{mounted_as}/#{model.id}"
end

def extension_white_list
%w(jpg jpeg gif png doc xls xlsx docx pdf txt zip rar ppt pptx)
end

I have my model

class MaterialAsignatura
include DataMapper::Resource
include DataMapper::Timestamps
include DataMapper::Historylog

storage_names[:default] = 'material_asignaturas'

property :id, Serial
timestamps :at
property :deleted_at, ParanoidDateTime
mount_uploader :source, ArchivoUploader

end

console output

SQL (0.186ms) BEGIN
SQL (1.542ms) INSERT INTO material_asignaturas (created_at, updated_at, source, seccion_dictada_id) VALUES ('2019-07-24 17:21:09', '2019-07-24 17:21:09', 'DIPLOMADO EN TIC.docx', 61784)
SQL (0.730ms) INSERT INTO historylogs (original_state, original_date, comment, historiable_type, historiable_id, created_at, updated_at) VALUES ('{"id":7,"created_at":"2019-07-24T17:21:09-04:00","updated_at":"2019-07-24T17:21:09-04:00","deleted_at":null,"source":{"url":"/uploads/material_asignatura/source/7/DIPLOMADO EN TIC.docx"},"seccion_dictada_id":61784}', '2019-07-24 17:21:09', 'Creado', 'MaterialAsignatura', 7, '2019-07-24 17:21:09', '2019-07-24 17:21:09')
default: commit
SQL (2.870ms) COMMIT