title: Creating json file in Symfony 2
body: <p>Hi I've created json object like that:</p>
  
  <pre><code>{"ask":[{"rate":"2110.00000000","amount":"2.00000000","price":"4220.00000000","degree":0.2},{"rate":"1800.00000000","amount":"5.00000000","price":"9000.00000000","degree":0.5},{"rate":"20.00000000","amount":"8.00000000","price":"160.00000000","degree":0.8}],"bid":[{"rate":"1700.00000000","amount":"0.50000000","price":"1700.00000000","degree":0.5}]} 
  </code></pre>
  
  <p>and I would like to create a file and put json to it, how can I do it?</p>