Creating a production ready API with Python and Django Rest Framework – part 1

The aim if this tutorial is to show how to create a production ready solution for a REST API, using Python and Django Rest Framework. I will show you how to first create a very basic API, how to handle the authentication and permissions and I will cover deployment and hosting of images. The full source code of the tutorial is available at: https://github.com/andreagrandi/drf-tutorial

Summary of the complete tutorial

  1. Create the basic structure for the API
  2. Add Authentication and POST methods
  3. Handling details and changes to existing data
  4. Testing the API
  5. Switching from Sqlite to PostgreSQL
  6. Hosting the API on Heroku
  7. Add an Image field and save images to S3

Create the basic structure for the API

For this tutorial I will assume you have correctly installed at least Python (I will use Python 2.7.x), virtualenv and virtualenvwrapper on your system and I will explain how to create everything else step by step.

Note: at the time of writing, the tutorial has been based on Django 1.10.1 and Django Rest Framework 3.4.7

Creating the main project structure

Data Model

We will create the API for a generic products catalog, using a very simple structure (to keep things simple). Edit the file catalog/models.py adding these lines:

after creating the model, we need to add ‘catalog’ application to INSTALLED_APPS. Edit settings.py and add the app at the end of the list:

at this point the Django application will be recognised by the project and we can create and apply the schema migration:

API Serializer

Serializers are those components used to convert the received data from JSON format to the relative Django model and viceversa. Create the new file catalog/serializers.py and place this code inside:

In this case we are using a ModelSerializer. We need to create a new class from it, and specify the model attribute, that’s it. In this case we also specify the fields we want to return.

API View

The serializer alone is not able to respond to an API request, that’s why we need to implement a view. In this first version of the view (that we will improve soon) we will “manually” transform the data available in the serializer dictionary to a JSON response. In catalog/views.py add this code:

At this point we need to tell our Django app to use this API view when a certain URL is requested. We first need to add this code in catalog/urls.py

and finally we need to add this to drftutorial/urls.py

Testing our work

At this point we should be able to start our Django app:

Let’s install a tool that will help us to test the API:

now we can use it to call our URL:

It works! It’s an empty response of course, because we still don’t have any data to show, but we will see later how to load some example data in our database. If you have been able to follow the tutorial up to this point, that’s good. If not, don’t worry. You can checkout the code at exactly this point of the tutorial doing:

Improving the API View

There is a quicker and more efficient way of implementing the same API view we have seen before. We can use a class based view, in particular the APIView class and also have the JSON response implemented automatically. Change the code inside catalog/views.py with this one:

You will also have to change catalog/urls.py in this way:

You can check the source code for this step of the tutorial with:

There is also another way of writing the same view. Let’s try it with ListAPIView. Edit catalog/views.py again and substitute the code with this one:

With a ListAPIView we are basically creating a read-only API that is supposed to return a list of items. We need to specify a queryset and the serializer_class parameters. Once again, you can get up to this point, checking out the related git tag:

Creating Initial Data

An API that doesn’t return any data is not very useful, right? Also, at the moment we haven’t implemented yet any feature that let us insert any data. That’s why I’ve created a data migration for you that will insert some data for you. You may notice that the example data contains some Italian products… out of the scope of this tutorial, I strongly advise you to google this products and if you ever happen to visit Italy, try them. You won’t regret!

Going back to our data migration, you first have to create an empty one with:

and then open the file that has been created under catalog/migrations/ named 0002_….. (your name will be different from mine, so just edit the one starting with 0002 and you will be fine) and fill it with this code:

to apply the migration we just created, just do:

If you try to test the API again from the command line, you will get these products back:

Again, you can get up to this point with:

One more thing…

No, we are not going to present a new amazing device, I’m sorry, but I want to show you a nice Django Rest Framework feature you can have without much additional work. Edit settings.py and add rest_framework to the list of INSTALLED_APPS:

Now, if you are still running the Django app, try to visit this url from your browser: http://127.0.0.1:8000/products/
That’s very nice, isn’t it? You can have browsable APIs at no cost.

Wrapping Up

I’ve mentioned at the beginning that this is just the first part of my API tutorial. In the next part I will show you how to let the consumer of your API add some products and leave reviews (we will introduce a new model for this). Also, we will see how to set proper permissions to these new API methods so that only admin users will be able to add products while normal users will be able to add reviews. So, if you feel ready, you can begin to follow the second part of this tutorial: https://www.andreagrandi.it/2016/10/01/creating-a-production-ready-api-with-python-and-django-rest-framework-part-2/

References

Some parts of this tutorial and a few examples have been taken directly from the original Django Rest Framework tutorial.