Scaffold didn't created Migration class name correctly: it should be "CreateTiposDeProva" instead of "CreateTipoDeProvas" plural should have gone in the middle of the sentence.

my definitions:

ActiveSupport::Inflector.pluralize('tipo_de_prova').camelize

plural in the middle of sentence

ActiveSupport::Inflector.inflections do |inflect| inflect.irregular 'tipo_de_prova', 'tipos_de_prova' inflect.plural 'tipo_de_prova', 'tipos_de_prova' inflect.singular 'tipos_de_prova', 'tipo_de_prova' end

when checking migrations, only class name wasn't OK:

class CreateTipoDeProvas < ActiveRecord::Migration def self.up

create_table :tipos_de_prova do |t|

...

end