.. _ref-tutorial:

=============================
Getting Started with Tastypie
=============================

Tastypie is a reusable app (that is, it relies only on its 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.

.. note::

    If you hit a stumbling block, you can join
    `#tastypie on irc.freenode.net`_ to get help.

.. _#tastypie on irc.freenode.net: irc://irc.freenode.net/tastypie

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.utils.text import slugify


    class Entry(models.Model):
        user = models.ForeignKey(User, on_delete=models.CASCADE)
        pub_date = models.DateTimeField(default=now)
        title = models.CharField(max_length=200)
        slug = models.SlugField(null=True, blank=True)
        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.


Installation
============

Installing Tastypie is as simple as checking out the source and adding it to
your project or ``PYTHONPATH``.

  1. Download the dependencies:

    * Python 2.7+ or Python 3.4+
    * Django 1.8+
    * ``python-mimeparse`` 0.1.4+ (http://pypi.python.org/pypi/python-mimeparse)
    * ``dateutil`` (http://labix.org/python-dateutil)
    * **OPTIONAL** - ``lxml`` (http://lxml.de/) and ``defusedxml``  (https://pypi.python.org/pypi/defusedxml) if using the XML serializer
    * **OPTIONAL** - ``pyyaml`` (http://pyyaml.org/) if using the YAML serializer

  2. Either check out tastypie from GitHub_ or to pull a release off PyPI_.
     Doing ``sudo pip install django-tastypie`` or
     ``sudo easy_install django-tastypie`` is all that should be required.
  3. Either symlink the ``tastypie`` directory into your project or copy the
     directory in. What ever works best for you.

.. _GitHub: https://github.com/django-tastypie/django-tastypie
.. _PyPI: http://pypi.python.org/pypi/django-tastypie


Configuration
=============

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 :doc:`settings`) but
they all have sane defaults and are not required unless you need to tweak their
values.


Creating Resources
==================

REST-style architecture talks about resources, so unsurprisingly integrating
with Tastypie involves creating :class:`~tastypie.resources.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 :class:`~tastypie.resources.ModelResource`
subclass, will introspect all non-relational fields on the ``Entry`` model and
create its own :mod:`ApiFields <tastypie.fields>` that map to those fields,
much like the way Django's ``ModelForm`` class introspects.

.. note::

    The ``resource_name`` within the ``Meta`` class is optional. If not
    provided, it is automatically generated off the classname, removing any
    instances of :class:`~tastypie.resources.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.urls.conf import re_path, include
    from myapp.api import EntryResource

    entry_resource = EntryResource()

    urlpatterns = [
        # The normal jazz here...
        re_path(r'^blog/', include('myapp.urls')),
        re_path(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.

.. note::

    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):

  * http://127.0.0.1:8000/api/entry/?format=json
  * http://127.0.0.1:8000/api/entry/1/?format=json
  * http://127.0.0.1:8000/api/entry/schema/?format=json
  * http://127.0.0.1:8000/api/entry/set/1;3/?format=json

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()

.. warning::

  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):
        # Maps `Entry.user` to a Tastypie `ForeignKey` field named `user`,
        # which gets serialized using `UserResource`. The first appearance of
        # 'user' on the next line of code is the Tastypie field name, the 2nd
        # appearance tells the `ForeignKey` it maps to the `user` attribute of
        # `Entry`. Field names and model attributes don't have to be the same.
        user = fields.ForeignKey(UserResource, 'user')

        class Meta:
            queryset = Entry.objects.all()
            resource_name = 'entry'

We simply created a new :class:`~tastypie.resources.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 :class:`~tastypie.api.Api` class, which lets you bind
multiple :class:`Resources <tastypie.resources.Resource>` 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.urls.conf import re_path, include
    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 = [
        # The normal jazz here...
        re_path(r'^blog/', include('myapp.urls')),
        re_path(r'^api/', include(v1_api.urls)),
    ]

Note that we're now creating an :class:`~tastypie.api.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:

  * http://127.0.0.1:8000/api/v1/?format=json
  * http://127.0.0.1:8000/api/v1/user/?format=json
  * http://127.0.0.1:8000/api/v1/user/1/?format=json
  * http://127.0.0.1:8000/api/v1/user/schema/?format=json
  * http://127.0.0.1:8000/api/v1/user/set/1;3/?format=json
  * http://127.0.0.1:8000/api/v1/entry/?format=json
  * http://127.0.0.1:8000/api/v1/entry/1/?format=json
  * http://127.0.0.1:8000/api/v1/entry/schema/?format=json
  * http://127.0.0.1:8000/api/v1/entry/set/1;3/?format=json

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:

  * :doc:`authentication`
  * :doc:`authorization`
  * :doc:`caching`
  * :doc:`throttling`
  * :doc:`resources` (filtering & sorting)
  * :doc:`serialization`

Tastypie is also very easy to override and extend. For some common patterns and
approaches, you should refer to the :doc:`cookbook` documentation.
