title: Django: How to get the current user id in viewsets
body: <p>This is my view using rest_framwork viewsets. I am a beginner at this please help.</p>
  <p>These are my serializer classes.</p>
  <pre><code>from django.contrib.auth.models import User
  from rest_framework.authtoken.models import Token
  from . import models
  
  class UserSerializer(serializers.ModelSerializer):
      class Meta:
          model = User
          fields = ('id', 'username', 'password')
          extra_kwargs = {'password': {'write_only': True, 'required': True}}
      
      def create(self, validated_data):
          user = User.objects.create_user(**validated_data)
          Token.objects.create(user=user)
          return user
  
  class ToDoSerializer(serializers.ModelSerializer):
      class Meta:
          model = models.ToDo
          fields = ('id', 'user', 'title', 'date')
  </code></pre>
  <p>These are my viewset classes.</p>
  <pre><code>from rest_framework.permissions import AllowAny, IsAuthenticated
  from rest_framework import viewsets
  from . import serializers, models
  from rest_framework.authentication import TokenAuthentication
  
  # Create your views here.
  
  class UserViewSet(viewsets.ModelViewSet):
      queryset = User.objects.all()
      serializer_class = serializers.UserSerializer
      permission_classes = (AllowAny, )
  
  class ToDoViewSet(viewsets.ModelViewSet):
      queryset = models.ToDo.objects.all()
      serializer_class = serializers.ToDoSerializer
      authentication_classes = (TokenAuthentication, )
      permission_classes = (IsAuthenticated, )
  </code></pre>
  <p>I didn't quite understand how to filter out based on the current user who is logged in.</p>