Getting Started with Tastypie¶
Tastypie is a reusable app (that is, it relies only on it’s own code and focuses on providing just a REST-style API) and is suitable for providing an API to any application without having to modify the sources of that app.
Not everyone’s needs are the same, so Tastypie goes out of its way to provide plenty of hooks for overriding or extending how it works.
If you hit a stumbling block, you can join #tastypie on irc.freenode.net to get help.
This tutorial assumes that you have a basic understanding of Django as well as how proper REST-style APIs ought to work. We will only explain the portions of the code that are Tastypie-specific in any kind of depth.
For example purposes, we’ll be adding an API to a simple blog application. Here is myapp/models.py:
from tastypie.utils.timezone import now from django.contrib.auth.models import User from django.db import models from django.template.defaultfilters import slugify class Entry(models.Model): user = models.ForeignKey(User) pub_date = models.DateTimeField(default=now) title = models.CharField(max_length=200) slug = models.SlugField() body = models.TextField() def __unicode__(self): return self.title def save(self, *args, **kwargs): # For automatic slug generation. if not self.slug: self.slug = slugify(self.title)[:50] return super(Entry, self).save(*args, **kwargs)
With that, we’ll move on to installing and configuring Tastypie.
Installing Tastypie is as simple as checking out the source and adding it to your project or PYTHONPATH.
- Download the dependencies:
- Python 2.4+
- Django 1.0+ (tested on Django 1.1+)
- mimeparse 0.1.3+ (http://code.google.com/p/mimeparse/)
- Older versions will work, but their behavior on JSON/JSONP is a touch wonky.
- dateutil (http://labix.org/python-dateutil)
- OPTIONAL - lxml (http://lxml.de/) if using the XML serializer
- OPTIONAL - pyyaml (http://pyyaml.org/) if using the YAML serializer
- OPTIONAL - uuid (present in 2.5+, downloadable from http://pypi.python.org/pypi/uuid/) if using the ApiKey authentication
Once tastypie reaches version 1.0, it will become officially available on PyPI. Once that is the case, a sudo pip install tastypie or sudo easy_install tastypie should be available.
The only mandatory configuration is adding 'tastypie' to your INSTALLED_APPS. This isn’t strictly necessary, as Tastypie has only two non-required models, but may ease usage.
You have the option to set up a number of settings (see Tastypie Settings) but they all have sane defaults and are not required unless you need to tweak their values.
REST-style architecture talks about resources, so unsurprisingly integrating with Tastypie involves creating Resource classes. For our simple application, we’ll create a file for these in myapp/api.py, though they can live anywhere in your application:
# myapp/api.py from tastypie.resources import ModelResource from myapp.models import Entry class EntryResource(ModelResource): class Meta: queryset = Entry.objects.all() resource_name = 'entry'
This class, by virtue of being a ModelResource subclass, will introspect all non-relational fields on the Entry model and create it’s own ApiFields that map to those fields, much like the way Django’s ModelForm class introspects.
The resource_name within the Meta class is optional. If not provided, it is automatically generated off the classname, removing any instances of Resource and lowercasing the string. So EntryResource would become just entry.
We’ve included the resource_name attribute in this example for clarity, especially when looking at the URLs, but you should feel free to omit it if you’re comfortable with the automatic behavior.
Hooking Up The Resource(s)¶
Now that we have our EntryResource, we can hook it up in our URLconf. To do this, we simply instantiate the resource in our URLconf and hook up its urls:
# urls.py from django.conf.urls.defaults import * from myapp.api import EntryResource entry_resource = EntryResource() urlpatterns = patterns('', # The normal jazz here... (r'^blog/', include('myapp.urls')), (r'^api/', include(entry_resource.urls)), )
Now it’s just a matter of firing up server (./manage.py runserver) and going to http://127.0.0.1:8000/api/entry/?format=json. You should get back a list of Entry-like objects.
The ?format=json is an override required to make things look decent in the browser (accept headers vary between browsers). Tastypie properly handles the Accept header. So the following will work properly:
curl -H "Accept: application/json" http://127.0.0.1:8000/api/entry/
But if you’re sure you want something else (or want to test in a browser), Tastypie lets you specify ?format=... when you really want to force a certain type.
At this point, a bunch of other URLs are also available. Try out any/all of the following (assuming you have at least three records in the database):
However, if you try sending a POST/PUT/DELETE to the resource, you find yourself getting “401 Unauthorized” errors. For safety, Tastypie ships with the authorization class (“what are you allowed to do”) set to ReadOnlyAuthorization. This makes it safe to expose on the web, but prevents us from doing POST/PUT/DELETE. Let’s enable those:
# myapp/api.py from tastypie.authorization import Authorization from tastypie.resources import ModelResource from myapp.models import Entry class EntryResource(ModelResource): class Meta: queryset = Entry.objects.all() resource_name = 'entry' authorization= Authorization()
This is now great for testing in development but VERY INSECURE. You should never put a Resource like this out on the internet. Please spend some time looking at the authentication/authorization classes available in Tastypie.
With just nine lines of code, we have a full working REST interface to our Entry model. In addition, full GET/POST/PUT/DELETE support is already there, so it’s possible to really work with all of the data. Well, almost.
You see, you’ll note that not quite all of our data is there. Markedly absent is the user field, which is a ForeignKey to Django’s User model. Tastypie does NOT introspect related data because it has no way to know how you want to represent that data.
And since that relation isn’t there, any attempt to POST/PUT new data will fail, because no user is present, which is a required field on the model.
This is easy to fix, but we’ll need to flesh out our API a little more.
Creating More Resources¶
In order to handle our user relation, we’ll need to create a UserResource and tell the EntryResource to use it. So we’ll modify myapp/api.py to match the following code:
# myapp/api.py from django.contrib.auth.models import User from tastypie import fields from tastypie.resources import ModelResource from myapp.models import Entry class UserResource(ModelResource): class Meta: queryset = User.objects.all() resource_name = 'user' class EntryResource(ModelResource): user = fields.ForeignKey(UserResource, 'user') class Meta: queryset = Entry.objects.all() resource_name = 'entry'
We simply created a new ModelResource subclass called UserResource. Then we added a field to EntryResource that specified that the user field points to a UserResource for that data.
Now we should be able to get all of the fields back in our response. But since we have another full, working resource on our hands, we should hook that up to our API as well. And there’s a better way to do it.
Adding To The Api¶
Tastypie ships with an Api class, which lets you bind multiple Resources together to form a coherent API. Adding it to the mix is simple.
We’ll go back to our URLconf (urls.py) and change it to match the following:
# urls.py from django.conf.urls.defaults import * from tastypie.api import Api from myapp.api import EntryResource, UserResource v1_api = Api(api_name='v1') v1_api.register(UserResource()) v1_api.register(EntryResource()) urlpatterns = patterns('', # The normal jazz here... (r'^blog/', include('myapp.urls')), (r'^api/', include(v1_api.urls)), )
Note that we’re now creating an Api instance, registering our EntryResource and UserResource instances with it and that we’ve modified the urls to now point to v1_api.urls.
This makes even more data accessible, so if we start up the runserver again, the following URLs should work:
Additionally, the representations out of EntryResource will now include the user field and point to an endpoint like /api/v1/users/1/ to access that user’s data. And full POST/PUT delete support should now work.
But there’s several new problems. One is that our new UserResource leaks too much data, including fields like email, password, is_active and is_staff. Another is that we may not want to allow end users to alter User data. Both of these problems are easily fixed as well.
Limiting Data And Access¶
Cutting out the email, password, is_active and is_staff fields is easy to do. We simply modify our UserResource code to match the following:
class UserResource(ModelResource): class Meta: queryset = User.objects.all() resource_name = 'user' excludes = ['email', 'password', 'is_active', 'is_staff', 'is_superuser']
The excludes directive tells UserResource which fields not to include in the output. If you’d rather whitelist fields, you could do:
class UserResource(ModelResource): class Meta: queryset = User.objects.all() resource_name = 'user' fields = ['username', 'first_name', 'last_name', 'last_login']
Now that the undesirable fields are no longer included, we can look at limiting access. This is also easy and involves making our UserResource look like:
class UserResource(ModelResource): class Meta: queryset = User.objects.all() resource_name = 'user' excludes = ['email', 'password', 'is_active', 'is_staff', 'is_superuser'] allowed_methods = ['get']
Now only HTTP GET requests will be allowed on /api/v1/user/ endpoints. If you require more granular control, both list_allowed_methods and detail_allowed_methods options are supported.
Beyond The Basics¶
We now have a full working API for our application. But Tastypie supports many more features, like:
Tastypie is also very easy to override and extend. For some common patterns and approaches, you should refer to the Tastypie Cookbook documentation.