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class="modal hide fade" tabindex="-1" role="dialog" aria-labelledby="myModalLabel" aria-hidden="true"> <div class="modal-header"> <button type="button" class="close" data-dismiss="modal" aria-hidden="true">×</button> <h3 id="myModalLabel">Documentation search</h3> </div> <div class="modal-body"> <form role="form" autocomplete="off"> <div class="form-group"> <input type="text" name="q" class="form-control" placeholder="Search..." id="mkdocs-search-query"> </div> </form> <div id="mkdocs-search-results"></div> </div> <div class="modal-footer"> <button class="btn" data-dismiss="modal" aria-hidden="true">Close</button> </div> </div> <div class="row-fluid"> <div class="span3"> <div id="table-of-contents"> <ul class="nav nav-list side-nav well sidebar-nav-fixed"> <li class="main"> <a href="#tutorial-3-class-based-views">Tutorial 3: Class Based Views</a> </li> <li> <a href="#rewriting-our-api-using-class-based-views">Rewriting our API using class based views</a> </li> <li> <a href="#using-mixins">Using mixins</a> </li> <li> <a href="#using-generic-class-based-views">Using generic class based views</a> </li> <div class="promo"> <hr/> <div id="sidebarInclude"> </div> </ul> </div> </div> <div id="main-content" class="span9"> <h1 id="tutorial-3-class-based-views"><a class="toclink" href="#tutorial-3-class-based-views">Tutorial 3: Class Based Views</a></h1> <p>We can also write our API views using class based views, rather than function based views. As we'll see this is a powerful pattern that allows us to reuse common functionality, and helps us keep our code <a href="http://en.wikipedia.org/wiki/Don't_repeat_yourself">DRY</a>.</p> <h2 id="rewriting-our-api-using-class-based-views"><a class="toclink" href="#rewriting-our-api-using-class-based-views">Rewriting our API using class based views</a></h2> <p>We'll start by rewriting the root view as a class based view. All this involves is a little bit of refactoring of <code>views.py</code>.</p> <pre><code>from snippets.models import Snippet from snippets.serializers import SnippetSerializer from django.http import Http404 from rest_framework.views import APIView from rest_framework.response import Response from rest_framework import status class SnippetList(APIView): """ List all snippets, or create a new snippet. """ def get(self, request, format=None): snippets = Snippet.objects.all() serializer = SnippetSerializer(snippets, many=True) return Response(serializer.data) def post(self, request, format=None): serializer = SnippetSerializer(data=request.data) if serializer.is_valid(): serializer.save() return Response(serializer.data, status=status.HTTP_201_CREATED) return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST) </code></pre> <p>So far, so good. It looks pretty similar to the previous case, but we've got better separation between the different HTTP methods. We'll also need to update the instance view in <code>views.py</code>.</p> <pre><code>class SnippetDetail(APIView): """ Retrieve, update or delete a snippet instance. """ def get_object(self, pk): try: return Snippet.objects.get(pk=pk) except Snippet.DoesNotExist: raise Http404 def get(self, request, pk, format=None): snippet = self.get_object(pk) serializer = SnippetSerializer(snippet) return Response(serializer.data) def put(self, request, pk, format=None): snippet = self.get_object(pk) serializer = SnippetSerializer(snippet, data=request.data) if serializer.is_valid(): serializer.save() return Response(serializer.data) return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST) def delete(self, request, pk, format=None): snippet = self.get_object(pk) snippet.delete() return Response(status=status.HTTP_204_NO_CONTENT) </code></pre> <p>That's looking good. Again, it's still pretty similar to the function based view right now.</p> <p>We'll also need to refactor our <code>urls.py</code> slightly now we're using class based views.</p> <pre><code>from django.conf.urls import url from rest_framework.urlpatterns import format_suffix_patterns from snippets import views urlpatterns = [ url(r'^snippets/$', views.SnippetList.as_view()), url(r'^snippets/(?P<pk>[0-9]+)/$', views.SnippetDetail.as_view()), ] urlpatterns = format_suffix_patterns(urlpatterns) </code></pre> <p>Okay, we're done. If you run the development server everything should be working just as before.</p> <h2 id="using-mixins"><a class="toclink" href="#using-mixins">Using mixins</a></h2> <p>One of the big wins of using class based views is that it allows us to easily compose reusable bits of behaviour.</p> <p>The create/retrieve/update/delete operations that we've been using so far are going to be pretty similar for any model-backed API views we create. Those bits of common behaviour are implemented in REST framework's mixin classes.</p> <p>Let's take a look at how we can compose the views by using the mixin classes. Here's our <code>views.py</code> module again.</p> <pre><code>from snippets.models import Snippet from snippets.serializers import SnippetSerializer from rest_framework import mixins from rest_framework import generics class SnippetList(mixins.ListModelMixin, mixins.CreateModelMixin, generics.GenericAPIView): queryset = Snippet.objects.all() serializer_class = SnippetSerializer def get(self, request, *args, **kwargs): return self.list(request, *args, **kwargs) def post(self, request, *args, **kwargs): return self.create(request, *args, **kwargs) </code></pre> <p>We'll take a moment to examine exactly what's happening here. We're building our view using <code>GenericAPIView</code>, and adding in <code>ListModelMixin</code> and <code>CreateModelMixin</code>.</p> <p>The base class provides the core functionality, and the mixin classes provide the <code>.list()</code> and <code>.create()</code> actions. We're then explicitly binding the <code>get</code> and <code>post</code> methods to the appropriate actions. Simple enough stuff so far.</p> <pre><code>class SnippetDetail(mixins.RetrieveModelMixin, mixins.UpdateModelMixin, mixins.DestroyModelMixin, generics.GenericAPIView): queryset = Snippet.objects.all() serializer_class = SnippetSerializer def get(self, request, *args, **kwargs): return self.retrieve(request, *args, **kwargs) def put(self, request, *args, **kwargs): return self.update(request, *args, **kwargs) def delete(self, request, *args, **kwargs): return self.destroy(request, *args, **kwargs) </code></pre> <p>Pretty similar. Again we're using the <code>GenericAPIView</code> class to provide the core functionality, and adding in mixins to provide the <code>.retrieve()</code>, <code>.update()</code> and <code>.destroy()</code> actions.</p> <h2 id="using-generic-class-based-views"><a class="toclink" href="#using-generic-class-based-views">Using generic class based views</a></h2> <p>Using the mixin classes we've rewritten the views to use slightly less code than before, but we can go one step further. REST framework provides a set of already mixed-in generic views that we can use to trim down our <code>views.py</code> module even more.</p> <pre><code>from snippets.models import Snippet from snippets.serializers import SnippetSerializer from rest_framework import generics class SnippetList(generics.ListCreateAPIView): queryset = Snippet.objects.all() serializer_class = SnippetSerializer class SnippetDetail(generics.RetrieveUpdateDestroyAPIView): queryset = Snippet.objects.all() serializer_class = SnippetSerializer </code></pre> <p>Wow, that's pretty concise. We've gotten a huge amount for free, and our code looks like good, clean, idiomatic Django.</p> <p>Next we'll move onto <a href="../4-authentication-and-permissions/">part 4 of the tutorial</a>, where we'll take a look at how we can deal with authentication and permissions for our API.</p> </div> <!--/span--> </div> <!--/row--> </div> <!--/.fluid-container--> </div> <!--/.body content--> <div id="push"></div> </div> <!--/.wrapper --> <footer class="span12"> <p>Documentation built with <a href="http://www.mkdocs.org/">MkDocs</a>. </p> </footer> <!-- Le javascript ================================================== --> <!-- Placed at the end of the document so the pages load faster --> <script src="../../js/jquery-1.8.1-min.js"></script> <script src="../../js/prettify-1.0.js"></script> <script src="../../js/bootstrap-2.1.1-min.js"></script> <script src="https://fund.django-rest-framework.org/sidebar_include.js"></script> <script>var base_url = '../..';</script> <script src="../../mkdocs/js/require.js"></script> <script src="../../js/theme.js"></script> <script> var shiftWindow = function() { scrollBy(0, -50) }; if (location.hash) shiftWindow(); window.addEventListener("hashchange", shiftWindow); $('.dropdown-menu').on('click touchstart', function(event) { event.stopPropagation(); }); // Dynamically force sidenav/dropdown to no higher than browser window $('.side-nav, .dropdown-menu').css('max-height', window.innerHeight - 130); $(function() { $(window).resize(function() { $('.side-nav, .dropdown-menu').css('max-height', window.innerHeight - 130); }); }); </script> </body> </html>