Add resource not exist protection

lib/generators/simple_controller/simple_controller_generator.rb

@@ -10,6 +10,7 @@ class SimpleControllerGenerator < Rails::Generators::NamedBase
 
   def setup
     @routes = RSpec::Rails::Swagger::RouteParser.new(controller_path.sub(/^\//, '')).routes
+    p "Warning!! Resource is not exist, CHECK & regenerate after you have configurate the model and routes already" if resource_class&.columns_hash.blank?
   end
 
   def create_controller_files

lib/generators/simple_controller/templates/specs/spec.rb.tt

@@ -4,9 +4,11 @@ require 'swagger_helper'
   type: :object, properties: {
     <%= singular_name %>: {
       type: :object, properties: {
+<% if resource_class&.columns_hash.present? -%>
 <% resource_class.columns_hash.except('id', 'created_at', 'updated_at').values.each do |column| -%>
         <%= column.name %>: { type: :<%= column.type %>, description: '' },
 <% end -%>
+<% end -%>
       }
     }
   }