title: How to apply Column defaults before a commit in sqlalchemy
body: <p>I have a declarative-base model:</p>
  
  <pre><code>class User(Base):
      id = Column(Integer, primary_key=True)
      money = Column(Integer, default=100)
  </code></pre>
  
  <p>and then I run</p>
  
  <pre><code>&gt;&gt;&gt; u = User()
  &gt;&gt;&gt; u.money
  None
  </code></pre>
  
  <p>How can I populate the defaults using sqlalchemy <em>without</em> writing anything to the database?</p>