title: sqlalchemy argument for postgresql serial primary key in pyramid framework
body: <p>I have found related questions but can't adapt them to my situation. <a href="https://stackoverflow.com/questions/15439514/sqlalchemy-and-auto-increments-with-postgresql">Here</a> and the postgresql docs <a href="http://docs.sqlalchemy.org/en/latest/dialects/postgresql.html#sequences-serial" rel="nofollow noreferrer">here</a>.</p>
  
  <p>I'm using sqlalchemy to interact with a postgresql db in a pyramid (python) framework (OS Ubuntu).  </p>
  
  <p>My schema is described in a <code>models.py</code> file.</p>
  
  <p>I'm trying to insert the record in my <code>views.py</code>:</p>
  
  <pre><code>cam_event = Event(key,'fileprefix',now,'CAM',outfile,
                    'new fake project','new fake memo')
  </code></pre>
  
  <p>where I would like to submit a null, none, or leave the position empty ('key' position in the line above) in my add command so that posgresql will fill it in.  When I do any of those  I get a "Programming Error" from one of the pyramid backend bits.</p>