title: get the actual value of the human-readable name from choices in django models
body: <p>I made this model:</p>
  
  <pre><code>name = models.CharField(max_length=3, choices=(
          ('sat', "Saturday"),
          ('sun', "Sunday"),
          ('mon', "Monday"),
          ('tue', "Tuesday"),
          ('wed', "Wednesday"),
          ('thu', "Thursday"),
          ('fri', "Friday"),
      ), null=False, blank=False, primary_key=True)
  
  </code></pre>
  
  <p>and when I want to get objects I can only access the human-readable name of choices.
  how can I get an object by human-readable name?
  I tried this but got an error:</p>
  
  <pre><code>Days.objects.get(name='saturday')
  </code></pre>