Migrate RailsAdmin's model to ActiveAdmin's model

admin_generator.rb

class AdminGenerator < Rails::Generators::Base
  argument :name, type: :string
  source_root File.expand_path('../templates', __FILE__)
  
  desc "Generates required files."
  def copy_controller_and_spec_files
    @model = name.to_s.constantize
    @attributes = @model.attribute_names.reject{|c| c.match(/^_id/)}.map(&:to_sym)
    template "resource.rb", "app/admin/#{name.underscore}.rb"
  end
end

resource.rb

ActiveAdmin.register <%= name %> do

  permit_params <%= @attributes.to_s.gsub(/\[|\]/,'') %>

  index do |<%= name.underscore %>|
    selectable_column
    id_column
  <% @attributes.each do |column_name| -%>
   column :<%= column_name %>
  <% end %>
    actions
  end

  show do
    attributes_table do
  <% @attributes.each do |column_name| -%>
   row :<%= column_name %>
  <% end %>
    end
  end

  form do |f|
    f.inputs do
  <% @attributes.each do |column_name| -%>
   f.input :<%= column_name %>
  <% end %>
    end
    actions
  end
end