title: Validating entities without form in Symfony 2
body: <p>I'm creating a REST API controller for Symfony 2. I started using the SensioGeneratorBundle to create a CRUD and modified the controller to act as a REST controller. However, i don't have forms so i'm thinking about removing this part.</p>
  
  <p>How can i validate my fields without a form? Everything is connected to the form and i want some freedom, including customizing field names. For example, POST x and y fields are interpreted by Symfony as title and content. </p>