title: Django: 'unique_together' and 'blank=True'
body: <p>I have a Django model which looks like this:</p>
  
  <pre><code>class MyModel(models.Model):
      parent = models.ForeignKey(ParentModel)
      name   = models.CharField(blank=True, max_length=200)
      ... other fields ...
  
      class Meta:
          unique_together = ("name", "parent")
  </code></pre>
  
  <p>This works as expected; If there is the same <code>name</code> more than once in the same <code>parent</code> then I get an error: "MyModel with this Name and Parent already exists." </p>
  
  <p>However, I also get an error when I save more than one <code>MyModel</code> with the same <code>parent</code> but with the <code>name</code> field blank, but this should be allowed. So basically I don't want to get the above error when the <code>name</code> field is blank. Is that possible somehow?</p>