Dynamic Loading Settings

app_config.rb

class AppConfig < ActiveRecord::Base

  validates :parameter, uniqueness: true, presence: true

  def self.get(parameter)
    AppConfig.where(parameter: parameter).first.try(:value)
  end

  def self.set(parameter, value)
    param = AppConfig.find_or_initialize_by(parameter: parameter)
    param.value = value
    param.save
  end

end

app_configs_controller.rb

class AppConfigsController < ApplicationController

  def edit
    authorize :settings
    configs = AppConfig.all
    @settings = Settings.new(configs)
  end

  def update
    authorize :settings

    settings_params.each do |parameter, value|
      AppConfig.transaction do
        begin
          config = AppConfig.set(parameter, value)
        end
      end
    end
    flash[:notice] = "Configurations successfuly updated"
    redirect_to edit_settings_path
  end

  private
  def settings_params
    #Novas configurações devem ser permitidas aqui
    params.require(:settings).permit(:language)
  end

end

edit.html.erb

<!-- Here You just need to worry about creating the fields that exists in the database -->
<%= simple_form_for @settings, url: save_settings_path do |f| %>

  <%= f.input :language, required: true, collection: Settings.language_options,
              selected: I18n.locale %>
  <%= f.button :submit, class: "btn-success" %>
  
<% end %>

routes.rb

get '/settings' => "app_configs#edit", as: :edit_settings
put '/settings' => "app_configs#update", as: :save_settings
patch '/settings' => "app_configs#update"

settings.rb

class Settings
  
  include ActiveModel::Model
  extend ActiveModel::Naming # Necessary for trasnlations

  # The constructor reveices an array of AppConfig containing all the configs
  # and then he translate it to settings porperties
  def initialize(app_configs)
    app_configs.each do |config|

      # Creates an attribute acessor (get and set) for the paremeter
      self.class.send(:attr_accessor, config.parameter)

      # Creates an instance varibale for the paremeter, passing the value
      instance_variable_set("@#{config.parameter}", config.value)

    end
  end

  def app_configs
    configs = []
    instance_variables.each do |variable|
      parameter = variable.to_s.sub!(/[^0-9A-Za-z]/, '') #Removes the '@'
      value = send(parameter) # Get the value of the parameter
      configs << { parameter: parameter, value: value }
    end
    configs
  end
  
  def self.language_options
    locales = []
    I18n.available_locales.each do |locale|
      locales << [I18n.t(locale, scope: :locales), locale]
    end
    locales
  end

end