title: convert datetime to string symfony 3.3
body: <p>Hi i have a field in my entity return an object (dateTime)</p>
  
  <pre><code>object(DateTime)[13335]
  public 'date' =&gt; string '1970-04-01 00:00:00.000000' (length=26)
  public 'timezone_type' =&gt; int 3
  public 'timezone' =&gt; string 'UTC' (length=3)
  </code></pre>
  
  <p>I would like to get Day,month,year as a string .</p>
  
  <p>How can I do this using php symfony in my controller.</p>