ruby on rails - How to update groupings via Mailchimp API? -

I am trying to subscribe and update members of a Mailchimp list of my Rail 3 3.2 app via API I am

Everything is working fine, except that I am unable to set up interest groups.

What is the correct format for group setting

I have tried

  merge_vers: 'grouping' = & gt; [['Id' = & gt; Group_id, 'groups' = & gt; ['Array', 'ka', 'group']]]   
 and  
  merge_vers: 'grouping' => [['Id' = & gt; Group_id, 'groups' = & gt; "Comma, different, group"]]   
 and  
  merge_vers: 'grouping' => [0 = & gt; ['Id' = & gt; Group_id, 'groups' = & gt;  
 And some other variations.  
 Nothing is working and docs are unclear  
 
 
 I took some time but Fenli detected the correct format:    @ gb.lists.subscribe ({: Id =>; list_id ,: email = & gt; { : Email = & gt; self.email},: merge_vars = & gt; {FNAME = & gt; self.firstname, groupings = & gt; [{: id = & gt; Grouping_id ,: groups = & gt; Wrong, send_welcome = & gt; wrong; update_existing = & gt; true})    P> I am using Rail 3.1.11 and Gbin 0.5.0  
 Hope this will help!