title: Rest Framework Django - Disable field to accept null values
body: <p>Rest Framework Django - Disable field to accept null values</p>
  
  <p>How can I configure for the serialized Model to accept blank fields?</p>
  
  <p>Warning</p>
  
  <pre><code>{"Operacao": ["This field can not be blank."]}
  </code></pre>
  
  <p>Model </p>
  
  <pre><code>class SEF(models.Model):
      operacao = models.CharField(max_length=10, null=True)
      documento = models.CharField(max_length=50, null=True)
      user = models.ForeignKey(User)
  </code></pre>
  
  <p>Serializer</p>
  
  <pre><code>class SEFCreateSerializer(serializers.ModelSerializer):
  
      class Meta:
          model = SEF
          fields = ('operacao', 'documento', 'user')
  </code></pre>
  
  <p>View</p>
  
  <pre><code>sef_create = SEFCreateSerializer(data=data, many=True)
          if sef_create.is_valid():
              sef_create.save()
              salvo = HTTP_200_OK
          else:
              salvo = sef_create.errors
  </code></pre>