Unleash the Potential of Python with Graphene Django Integration

Introduction

Graphene Django has several additional features that are designed to make working with Django easy. Our primary focus in this tutorial is to give a good understanding of how to connect models from Django ORM to Graphene object types.

Set Up the Django Project

We will set up the project, and create the following:

🔷 An Django project called a cookbook
🔷 An app within the cookbook called ingredients

# Create a virtualenv to isolate our package dependencies locally
virtualenv env
source env/bin/activate # On Windows use `env\Scripts\activate`

# Install Django and Graphene with Django support
pip install django graphene_django

# Set up a new project with a single application
django-admin startproject cookbook . # Note the trailing '.' character
cd cookbook
django-admin startapp ingredients

Now sync your database for the first time:

python manage.py migrate

Let’s create a few simple models…

Defining Our Models

Let’s get started with these models:

# cookbook/ingredients/models.py
from django.db import models

class Category(models.Model):
name = models.CharField(max_length=100)

def __str__(self):
return self.name

class Ingredient(models.Model):
name = models.CharField(max_length=100)
notes = models.TextField()
category = models.ForeignKey(
Category, related_name="ingredients", on_delete=models.CASCADE
)

def __str__(self):
return self.name

Add ingredients as INSTALLED_APPS:

# cookbook/settings.py

INSTALLED_APPS = [
...
# Install the ingredients app
"cookbook.ingredients",
]

Don’t forget to create & run migrations:

python manage.py makemigrations
python manage.py migrate

Load Some Test Data

You can use the Django admin interface to create some data yourself. You’ll need to run the development server (see below), and create a login for yourself too (python manage.py createsuperuser).

Register models with admin panel:

# cookbook/ingredients/admin.py
from django.contrib import admin
from cookbook.ingredients.models import Category, Ingredient

admin.site.register(Category)
admin.site.register(Ingredient)

GraphQL – Schema and Object Types

To make queries to our Django project, we are going to need a few things:

🔷 Schema with defined object types
🔷 A view, taking queries as input and returning the result

GraphQL presents your objects to the world as a graph structure rather than a more hierarchical structure to which you may be accustomed. To create this representation, Graphene needs to know about each type of object which will appear in the graph.

This graph also has a root type through which all access begins. This is the Query class below.

To create GraphQL types for each of our Django models, we will subclass the DjangoObjectType class which will automatically define GraphQL fields that correspond to the fields on the Django models.

Learn How to Get Started with GraphQL 👇🏼

After we’ve done that, we will list those types as fields in the Query class.

Create cookbook/schema.py and type the following:

# cookbook/schema.py
import graphene
from graphene_django import DjangoObjectType

from cookbook.ingredients.models import Category, Ingredient

class CategoryType(DjangoObjectType):
class Meta:
model = Category
fields = ("id", "name", "ingredients")

class IngredientType(DjangoObjectType):
class Meta:
model = Ingredient
fields = ("id", "name", "notes", "category")

class Query(graphene.ObjectType):
all_ingredients = graphene.List(IngredientType)
category_by_name = graphene.Field(CategoryType, name=graphene.String(required=True))

def resolve_all_ingredients(root, info):
# We can easily optimize query count in the resolve method
return Ingredient.objects.select_related("category").all()

def resolve_category_by_name(root, info, name):
try:
return Category.objects.get(name=name)
except Category.DoesNotExist:
return None

schema = graphene.Schema(query=Query)

You can think of this as being something like your top-level urls.py file.

Testing Everything So Far

We are going to do some configuration work, in order to have a working Django where we can test queries, before we move on, updating our schema.

Update Settings

Next, install your app and GraphiQL in your Django project. GraphiQL is a web-based integrated development environment to assist in the writing and executing of GraphQL queries. It will provide us with a simple and easy way of testing our cookbook project.

Add graphene_django to INSTALLED_APPS in cookbook/settings.py:

# cookbook/settings.py

INSTALLED_APPS = [
...
"graphene_django",
]

And then add the SCHEMA to the GRAPHENE config in cookbook/settings.py:

# cookbook/settings.py

GRAPHENE = {
"SCHEMA": "cookbook.schema.schema"
}

Alternatively, we can specify the schema to be used in the URL definition, as explained below.

Creating GraphQL and GraphiQL Views

Unlike a RESTful API, there is only a single URL from which GraphQL is accessed. Requests to this URL are handled by Graphene’s GraphQLView view.

This view will serve as a GraphQL endpoint. As we want to have the GraphiQL as mentioned above we specify that on the parameters with graphiql=True.

# cookbook/urls.py

from django.contrib import admin
from django.urls import path
from django.views.decorators.csrf import csrf_exempt

from graphene_django.views import GraphQLView

urlpatterns = [
path("admin/", admin.site.urls),
path("graphql", csrf_exempt(GraphQLView.as_view(graphiql=True))),
]

If we didn't specify the target schema in the Django settings file as explained above, we can do so here using:
# cookbook/urls.py

from django.contrib import admin
from django.urls import path
from django.views.decorators.csrf import csrf_exempt

from graphene_django.views import GraphQLView

from cookbook.schema import schema

urlpatterns = [
path("admin/", admin.site.urls),
path("graphql", csrf_exempt(GraphQLView.as_view(graphiql=True, schema=schema))),
]

Testing Our GraphQL Schema

We’re now ready to test the API we’ve built. Let’s fire up the server from the command line.

python manage.py runserver

Performing system checks...
Django version 3.0, using settings 'cookbook.settings'
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.

Go to localhost:8000/graphql and type your first query!

query {
allIngredients {
id
name
}
}

If you are using the provided fixtures, you will see the following response:

{
"data": {
"allIngredients": [
{
"id": "1",
"name": "Eggs"
},
{
"id": "2",
"name": "Milk"
},
{
"id": "3",
"name": "Beef"
},
{
"id": "4",
"name": "Chicken"
}
]
}
}

Congratulations, you have created a working GraphQL server!

Getting Relations

Using the current schema we can query for relations too. This is where GraphQL becomes really powerful!
For example, we may want to get a specific categories and list all ingredients that are in that category.
We can do that with the following query:

query {
categoryByName(name: "Dairy") {
id
name
ingredients {
id
name
}
}
}

This will give you (in case you are using the fixtures) the following result:

{
"data": {
"categoryByName": {
"id": "1",
"name": "Dairy",
"ingredients": [
{
"id": "1",
"name": "Eggs"
},
{
"id": "2",
"name": "Milk"
}
]
}
}
}

We can also list all ingredients and get information for the category they are in:

query {
allIngredients {
id
name
category {
id
name
}
}
}