title: How to store the current logged user id or active user id in odoo 9?
body: <p>In expenses, anyone has to approve the expense list, I want to display which user is Approved that?</p>
  
  <p>I just select all res.users as one2many</p>
  
  <pre><code>approved_by=fields.Many2one('res.users','Approved By')
  </code></pre>
  
  <p>In XML</p>
  
  <pre><code>&lt;field name="approved_by" /&gt;
  </code></pre>
  
  <p>Here it will display all users. But I want to display only logged user and it must be selected as default.</p>