title: best method to keep and update unique data entries google app engine python
body: <p>What is the best method to create a database for the given example model and assign each entry with a unique key/name which I already have and to overwrite it if the given key/name shows up again. From what I read you are supposed to use keyname? But I am not getting it to overwrite.</p>
  
  <pre><code>class SR(db.Model):
      name = db.StringProperty()
      title = db.StringProperty()
      url = db.StringProperty()
  
  s = SR(key_name="t5-2rain")
  s.name = 't5-2rain'
  s.title = 'kaja'
  s.url = 'okedoke'
  db.put(s)
  </code></pre>
  
  <p>If I enter this again with the same key name but different title value, will create another entry how do I overwrite an existing value with the same key-name.</p>
  
  <p><strong><em>Basically how do I populate a table with unique identifiers and overwrite values if the same unique identifier already exist?</em></strong>
  I realize I can search for an existing name or key name etc, call that object make the changes to the instances and repopulate but, I would imagine there has to be a better method than that for overwriting especially if I am trying to put a list where some values may be overwrites and some not.</p>