title: Symfony 2/3 REST API Validation without form
body: <p>For example I have entity Cat with property $name(string).</p>
  
  <p>I send to url POST /cats with parameter [name = 123]</p>
  
  <p>How I can validate data from request without form? Or REST API with form validation it's normal? I can't find information about validation without form. I can use Validation component without form, but maybe exists some bundle who can give me better approaches than $this->get('validator')->validate('data from request').</p>
  
  <p>Thanks.</p>