title: KeyError:'DATABASE_URL' when trying to connect to Heroku Postgress with SQL Alchemy
body: <p>I am running a Flask application trying to connect to Heroku's Postgres via SQLAlchemy.  I am getting an error at this line:</p>
  
  <pre><code>app.config['SQLALCHEMY_DATABASE_URI'] = os.environ['DATABASE_URL']
  
  raise KeyError(key)
  KeyError: 'DATABASE_URL'
  </code></pre>
  
  <p>I have provisioned a database in heroku and in the dashboard on the heroku site it gives a value for DATABASE_URL.  When I type heroku config: get DATABASE_URL I get a resulting url.  </p>
  
  <p>When I type in:</p>
  
  <pre><code>$python
  print os.environ['DATABASE_URL']
  </code></pre>
  
  <p>I get the key error again. DATABASE_URL is not showing up in this os.environ file.  How do I add it?</p>
  
  <p>I am running Windows 10 and tried adding the url as an environmnent variable to Windows 10.  Did not help.</p>
  
  <p>If anyone can shed light on the issue, please respond.</p>