title: DRF: How to get object in ModelSerializer.validate()
body: <p>I need to get the current object in ModelSerializer.validate() when it's being updated(not created)</p>
  <p>Currently, I'm using <code>self._args[0]</code></p>
  <pre class="lang-py prettyprint-override"><code>class UserInfoSerializer(serializers.ModelSerializer):
  
      class Meta:
          model = UserInfo
          fields = ('id', 'Username')
  
      def validate(self, data):
          current_user = self._args[0]  # &lt;--
  
  </code></pre>
  <p>It's something like <code>self.get_object()</code> in ViewSet</p>
  <p>I wonder if there is a better way to get what I want, any idea? thanks</p>