title: sqlalchemy FULL OUTER JOIN
body: <p>How to implement FULL OUTER JOIN in sqlalchemy  on orm level.</p>
  
  <p>Here my code:</p>
  
  <pre><code>q1 = (db.session.query(
          tb1.user_id.label('u_id'),
          func.count(tb1.id).label('tb1_c')
      )
      .group_by(tb1.user_id)
  )
  q2 = (db.session.query(
          tb2.user_id.label('u_id'),
          func.count(tb2.id).label('tb2_c')
      )
      .group_by(tb2.user_id)
  )
  </code></pre>
  
  <p>above two queries and I want to apply FULL OUTER JOIN on them.</p>