title: Django queryset - Isn’t it possible to filter on a FloatField?
body: <p>I’m trying to do a very simple operation but I get an issue.
  I have a simple model :</p>
  
  <pre><code>class MyModel(models.Model):
      date = models.DateTimeField(null=False)
      value = models.FloatField(null=True)
      interval = models.IntegerField(null=True)
  </code></pre>
  
  <p>My goal is to get the MyModel object with the biggest value.</p>
  
  <pre><code>#Get the value
  value = MyModel.objects.filter(date__gte=’2014-05-01’, date__lte=’2014-05-31’).aggregate(Max(‘value’))[‘value__max’]
  
  # Get the object corresponding to the max value
  my_object = MyModel.objects.get(value=value)
  </code></pre>
  
  <p>This code raise me an error : “matching query does not exist” …
  I tried to hardcode a value (that exists), I have the same error.</p>
  
  <p>Am I doing something wrong ? Isn’t it possible to filter on a FloatField ?</p>
  
  <p>Thanks.</p>