title: Django rest framework to_representation must be implemented
body: <p>This issue has similar headings to other threads on this forum, but I'm sure this is not a duplicate because one because I didn't overwrite my pagination details or anything (which turned out to be the cause in other questions).</p>
  <p>Anyways, Django raised <code>to_representation()</code> must be implemented. I'm completely stuck as there is no relevant documentation regarding this (please comment if you have some) and my case didn't fit in with other people's.</p>
  <p><strong>For those of you that think I didn't include everything in the error message, the error message is just this short and ambiguous.</strong> View this on <a href="https://github.com/encode/django-rest-framework/issues/7422" rel="nofollow noreferrer">github issues</a></p>
  <p><a href="https://i.stack.imgur.com/oeu1L.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oeu1L.png" alt="enter image description here" /></a></p>
  <p>Code:</p>
  <p>settings</p>
  <pre class="lang-py prettyprint-override"><code>INSTALLED_APPS = ['rest_framework',]
  
  REST_FRAMEWORK = {
      'DEFAULT_PAGINATION_CLASS': 'rest_framework.pagination.PageNumberPagination',
      'PAGE_SIZE': 10
  }
  </code></pre>
  <p>view</p>
  <pre class="lang-py prettyprint-override"><code>from rest_framework import viewsets
  from .models import Todo
  from .serializers import TodoSerializer
  
  class TodoViewSet(viewsets.ModelViewSet):
      queryset = Todo.objects.all()
      serializer_class = TodoSerializer
  </code></pre>
  <p>serializers</p>
  <pre class="lang-py prettyprint-override"><code>from .models import Todo
  from rest_framework import serializers
  
  class TodoSerializer(serializers.BaseSerializer):
      class Meta:
          model = Todo
          fields = ['title', 'desc', 'level', 'created']
  </code></pre>
  <p>urls</p>
  <pre class="lang-py prettyprint-override"><code>from django.urls import path, include
  from rest_framework import routers
  
  router = routers.DefaultRouter()
  router.register(r'todos', views.TodoViewSet)
  urlpatterns = [
      path('api/', include(router.urls)),
  ]
  </code></pre>
  <p>Many thanks in advance. Note: in case you're wondering is this all, this IS all as I jus started to learn drf a few moments ago.</p>