title: Why codeigniter output class return empty an array when created dynamically
body: <p>Im trying to fill an array dynamically this way:</p>
  
  <pre><code>    $columns = array();
      foreach ($this-&gt;get_selectors() as $value) {
      $element = array();
          $element['data']= $value;
          $columns[]= $element;
      }
  </code></pre>
  
  <p>the output $var_dump($columns) to this is:</p>
  
  <pre><code>  array(4) {
       [0]=&gt;
         array(1) {
           ["data"]=&gt;
               string(3) "one"
         }
       [1]=&gt;
         array(1) {
           ["data"]=&gt;
               string(3) "two"
         }
       [2]=&gt;
         array(1) {
           ["data"]=&gt;
               string(5) "three"
         }
       [3]=&gt;
         array(1) {
           ["data"]=&gt;
               string(4) "four"
         }
    }
  </code></pre>
  
  <p>But when i try to pass it through</p>
  
  <pre><code>    $this-&gt;output-&gt;set_content_type('application/json')
                                      -&gt;set_output(json_encode($columns));
  </code></pre>
  
  <p>I get nothing.</p>