title: How do you save a single space (" ") in a field in a django Model?
body: <p>My model definition looks like this:  </p>
  
  <pre><code>class MyModel(models.Model):
      tag_separator = models.CharField(max_length=1, null=True, blank=True)
  </code></pre>
  
  <p>The <code>tag_separator</code> is a single character, and it can be a single space: <code>" "</code>.<br>
  I need to select <code>null=True</code> in order to get it to work, but when I POST data through my REST API, it saves the <code>tag_separator</code> as an empty string: <code>"tag_separator": ""</code>.  </p>
  
  <p>Is there a simple way to stop Django from assuming that my single space string is an empty string?</p>
  
  <p>I am using: <code>Django==1.11</code> and <code>djangorestframework==3.7.7</code></p>