1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
|
<!DOCTYPE html>
<html lang="en">
<head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<meta charset="utf-8">
<title>Tutorial 3: Class Based Views - Django REST framework</title>
<link href="http://www.django-rest-framework.org/img/favicon.ico" rel="icon" type="image/x-icon">
<link rel="canonical" href="http://www.django-rest-framework.org/tutorial/3-class-based-views"/>
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta name="description" content="Django, API, REST, Tutorial 3: Class Based Views">
<meta name="author" content="Tom Christie">
<!-- Le styles -->
<link href="http://www.django-rest-framework.org/css/prettify.css" rel="stylesheet">
<link href="http://www.django-rest-framework.org/css/bootstrap.css" rel="stylesheet">
<link href="http://www.django-rest-framework.org/css/bootstrap-responsive.css" rel="stylesheet">
<link href="http://www.django-rest-framework.org/css/default.css" rel="stylesheet">
<!-- Le HTML5 shim, for IE6-8 support of HTML5 elements -->
<!--[if lt IE 9]>
<script src="http://html5shim.googlecode.com/svn/trunk/html5.js"></script>
<![endif]-->
<script type="text/javascript">
var _gaq = _gaq || [];
_gaq.push(['_setAccount', 'UA-18852272-2']);
_gaq.push(['_trackPageview']);
(function() {
var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true;
ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js';
var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s);
})();
</script>
</head>
<body onload="prettyPrint()" class="3-class-based-views-page">
<div class="wrapper">
<div class="navbar navbar-inverse navbar-fixed-top">
<div class="navbar-inner">
<div class="container-fluid">
<a class="repo-link btn btn-primary btn-small" href="https://github.com/tomchristie/django-rest-framework/tree/master">GitHub</a>
<a class="repo-link btn btn-inverse btn-small " href="../tutorial/4-authentication-and-permissions">Next <i class="icon-arrow-right icon-white"></i></a>
<a class="repo-link btn btn-inverse btn-small " href="../tutorial/2-requests-and-responses"><i class="icon-arrow-left icon-white"></i> Previous</a>
<a class="repo-link btn btn-inverse btn-small" href="#searchModal" data-toggle="modal"><i class="icon-search icon-white"></i> Search</a>
<a class="btn btn-navbar" data-toggle="collapse" data-target=".nav-collapse">
<span class="icon-bar"></span>
<span class="icon-bar"></span>
<span class="icon-bar"></span>
</a>
<a class="brand" href="http://www.django-rest-framework.org">Django REST framework</a>
<div class="nav-collapse collapse">
<ul class="nav">
<li><a href="http://www.django-rest-framework.org">Home</a></li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown">Tutorial <b class="caret"></b></a>
<ul class="dropdown-menu">
<li><a href="http://www.django-rest-framework.org/tutorial/quickstart">Quickstart</a></li>
<li><a href="http://www.django-rest-framework.org/tutorial/1-serialization">1 - Serialization</a></li>
<li><a href="http://www.django-rest-framework.org/tutorial/2-requests-and-responses">2 - Requests and responses</a></li>
<li><a href="http://www.django-rest-framework.org/tutorial/3-class-based-views">3 - Class based views</a></li>
<li><a href="http://www.django-rest-framework.org/tutorial/4-authentication-and-permissions">4 - Authentication and permissions</a></li>
<li><a href="http://www.django-rest-framework.org/tutorial/5-relationships-and-hyperlinked-apis">5 - Relationships and hyperlinked APIs</a></li>
<li><a href="http://www.django-rest-framework.org/tutorial/6-viewsets-and-routers">6 - Viewsets and routers</a></li>
</ul>
</li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown">API Guide <b class="caret"></b></a>
<ul class="dropdown-menu">
<li><a href="http://www.django-rest-framework.org/api-guide/requests">Requests</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/responses">Responses</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/views">Views</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/generic-views">Generic views</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/viewsets">Viewsets</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/routers">Routers</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/parsers">Parsers</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/renderers">Renderers</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/serializers">Serializers</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/fields">Serializer fields</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/relations">Serializer relations</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/authentication">Authentication</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/permissions">Permissions</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/throttling">Throttling</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/filtering">Filtering</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/pagination">Pagination</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/content-negotiation">Content negotiation</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/format-suffixes">Format suffixes</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/reverse">Returning URLs</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/exceptions">Exceptions</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/status-codes">Status codes</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/testing">Testing</a></li>
<li><a href="http://www.django-rest-framework.org/api-guide/settings">Settings</a></li>
</ul>
</li>
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown">Topics <b class="caret"></b></a>
<ul class="dropdown-menu">
<li><a href="http://www.django-rest-framework.org/topics/documenting-your-api">Documenting your API</a></li>
<li><a href="http://www.django-rest-framework.org/topics/ajax-csrf-cors">AJAX, CSRF & CORS</a></li>
<li><a href="http://www.django-rest-framework.org/topics/browser-enhancements">Browser enhancements</a></li>
<li><a href="http://www.django-rest-framework.org/topics/browsable-api">The Browsable API</a></li>
<li><a href="http://www.django-rest-framework.org/topics/rest-hypermedia-hateoas">REST, Hypermedia & HATEOAS</a></li>
<li><a href="http://www.django-rest-framework.org/topics/contributing">Contributing to REST framework</a></li>
<li><a href="http://www.django-rest-framework.org/topics/rest-framework-2-announcement">2.0 Announcement</a></li>
<li><a href="http://www.django-rest-framework.org/topics/2.2-announcement">2.2 Announcement</a></li>
<li><a href="http://www.django-rest-framework.org/topics/2.3-announcement">2.3 Announcement</a></li>
<li><a href="http://www.django-rest-framework.org/topics/release-notes">Release Notes</a></li>
<li><a href="http://www.django-rest-framework.org/topics/credits">Credits</a></li>
</ul>
</li>
</ul>
<ul class="nav pull-right">
<!-- TODO
<li class="dropdown">
<a href="#" class="dropdown-toggle" data-toggle="dropdown">Version: 2.0.0 <b class="caret"></b></a>
<ul class="dropdown-menu">
<li><a href="#">Trunk</a></li>
<li><a href="#">2.0.0</a></li>
</ul>
</li>
-->
</ul>
</div><!--/.nav-collapse -->
</div>
</div>
</div>
<div class="body-content">
<div class="container-fluid">
<!-- Search Modal -->
<div id="searchModal" 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">
<!-- Custom google search -->
<script>
(function() {
var cx = '015016005043623903336:rxraeohqk6w';
var gcse = document.createElement('script');
gcse.type = 'text/javascript';
gcse.async = true;
gcse.src = (document.location.protocol == 'https:' ? 'https:' : 'http:') +
'//www.google.com/cse/cse.js?cx=' + cx;
var s = document.getElementsByTagName('script')[0];
s.parentNode.insertBefore(gcse, s);
})();
</script>
<gcse:search></gcse:search>
</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">
<!-- TODO
<p style="margin-top: -12px">
<a class="btn btn-mini btn-primary" style="width: 60px">« previous</a>
<a class="btn btn-mini btn-primary" style="float: right; margin-right: 8px; width: 60px;">next »</a>
</p>
-->
<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>
</div>
</ul>
</div>
</div>
<div id="main-content" class="span9">
<h1 id="tutorial-3-class-based-views">Tutorial 3: Class Based Views</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">Rewriting our API using class based views</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 class="prettyprint lang-py"><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 class="prettyprint lang-py"><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 class="prettyprint lang-py"><code>from django.conf.urls import patterns, url
from rest_framework.urlpatterns import format_suffix_patterns
from snippets import views
urlpatterns = patterns('',
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">Using mixins</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 class="prettyprint lang-py"><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 class="prettyprint lang-py"><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">Using generic class based views</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 class="prettyprint lang-py"><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>Sponsored by <a href="http://dabapps.com/">DabApps</a>.</a></p>
</footer>
<!-- Le javascript
================================================== -->
<!-- Placed at the end of the document so the pages load faster -->
<script src="http://www.django-rest-framework.org/js/jquery-1.8.1-min.js"></script>
<script src="http://www.django-rest-framework.org/js/prettify-1.0.js"></script>
<script src="http://www.django-rest-framework.org/js/bootstrap-2.1.1-min.js"></script>
<script>
//$('.side-nav').scrollspy()
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 to no higher than browser window
$('.side-nav').css('max-height', window.innerHeight - 130);
$(function(){
$(window).resize(function(){
$('.side-nav').css('max-height', window.innerHeight - 130);
});
});
</script>
</body></html>
|
