title: Form data (array type) -> Database (serialize text) in Symfony2
body: <p>My database has a column named 'value' which used to store data from submit form. It's a 'text' type. How can I do to store an array from Form, I mean I want to serialize array data before save it to database?</p>
  
  <p>For example I have</p>
  
  <pre><code>builder-&gt;add('countries', 'country', array(
                  'multiple' =&gt; true,
                  'required' =&gt; false
              )
          )
  </code></pre>
  
  <p>and I want to store this countries data to 'value' column.</p>