如何在symfony2中从数据库中呈现Twig模板

I'm working on application written in symfony2 and I want to send email after some action/event... the problem is, that users can definig something like "email templates" which stores in db like simple string, for example: "This is some email from {{ user }}" and I need to render body for email from that template... In symfony documentation from this link: I'm working on application written in symfony2