refactor some methods

app/controllers/application_controller.rb

@@ -39,8 +39,8 @@ class ApplicationController < ActionController::API
   private
 
   def allow_client_application
-    app = Application.find_by_application_id(request.headers["PortalMEC-AppID"])
-    user_not_authorized if (app.try(:domain) != request.domain) || app.nil?
+    app = Application.find_or_initialize_by(application_id: request.headers["PortalMEC-AppID"].to_s)
+    user_not_authorized if app.domain != request.domain
   end
 
   def user_not_authorized

app/models/application.rb

@@ -8,6 +8,7 @@ class Application < ActiveRecord::Base
   private
 
   def generate_application_id
-    self.application_id = SecureRandom.uuid
+    @application_id = SecureRandom.uuid.to_s
+    generate_application_id if self.class.find_by_application_id(@application_id)
   end
 end