title: Why sqlalchemy add \ to " for a perfect JSON string to postgresql json field?
body: <p>SQLAlchemy 0.9 added built-in support for the JSON data type of PostgreSQL. But when I defined an object mapper which has a JSON field and set its value to a perfect JSON string:</p>
  
  <pre><code>json = '{"HotCold":"Cold,"Value":"10C"}'
  </code></pre>
  
  <p>The database gets the data in the form:</p>
  
  <pre><code>"{\"HotCold\":\"Cold\",\"Value":\"10C\"}"
  </code></pre>
  
  <p>All internal double quotes are backslashed, but if I set JSON from a python dict:</p>
  
  <pre><code>json = {"HotCold": "Cold, "Value": "10C"}
  </code></pre>
  
  <p>I get the JSON data in the database as:</p>
  
  <pre><code>{"HotCold":"Cold,"Value":"10C"}
  </code></pre>
  
  <p>Why is that? Do I have to pass the data in dict form to make it compatible with SQLAlchemy JSON support?</p>