title: Many to many table with an extra column in Rails
body: <p>Is it possible to do this with only two Rails models, User and Event:</p>
  <pre><code>Users
  |id        |name         |age         |
  |1         |danilo       |26          |
  |2         |joe          |23          |
  |3         |carlos       |50          |
  |4         |katy         |45          |
  
  Events_Users
  |event_id     |user_id        |confirmed       |
  |1            |1              |1               |
  |3            |3              |0               |
  |4            |3              |1               |
  |2            |3              |1               |
  
  Events
  |id           |name                     |date            |
  |1            |the end of the year      |31/12/2012      |
  |2            |the end of the world     |21/12/2012      |
  |3            |Party                    |18/12/2012      |
  |4            |Dinner                   |19/12/2012      |
  </code></pre>
  <p>The problem is, the user can confirm or not their presence in an
  event, for this I used the table Events_Users, column confirmed (1 for
  confirmed). How can I do this with Rails ActiveRecord without an model
  &quot;Event_User&quot;? How can I manipulate the confirmed column in the User
  model?</p>
  <p>I am using Rails 3.2.9 .</p>