title: What to insert into Postgres json type column if value is None
body: <p>psycopg2 inserts null into a column when inserting None.</p>
  
  <pre><code>...
  foo=json.dumps(insertObj.get('foo', None)),
  
  ...
  
  db.session.add(s)
  db.session.commit()
  </code></pre>
  
  <p>The value in the column is a string 'null' not the database type <code>null</code> which looks like <code>&lt;null&gt;</code> in the database manager. I thought it should insert database type null for None (see this  <a href="https://stackoverflow.com/questions/32959336/how-to-insert-null-value-in-sqlalchemy">question</a>).</p>
  
  <p>What should be inserted into a json column for an empty json value for best practice?</p>