ok so I suppose that you are here because you have not been able to find enough resources out there regarding the usage of GraphQL with Django. Congratulation, you have come to the right place. After slogging through the internet to find all the information that is needed, I have decided to put up an article regarding some basic usage of GraphQL, mainly CRUD operations, with Django.<\/p>\n
So lets get started from the scratch with a new django project.
\nFirst thing, install django and graphene for django.
\ngraphene_django is a python package that allows django to act as a GraphQL Server. And django-filter is needed for the example to handles filters in query, you may not need this in your own project.<\/p>\n
pip install django\npip install graphene_django\npip install django-filter <\/code><\/pre>\nIf you have virtualenv\/virtualenvwrapper installed, feel free to use it before running this.<\/p>\n
Next lets create a project folder for django<\/p>\n
mkdir GraphQLExample\ncd GraphQLExample<\/code><\/pre>\nCreate the django project and django app.<\/p>\n
django-admin.py startproject catalog\ncd catalog\ndjango-admin.py startapp books\npython3 manage.py migrate<\/code><\/pre>\nPlease check and make sure that your project folder structure looks like this:<\/p>\n
GraphQLExample\n|_catalog\n |_catalog\n |_books\n |_manage.py \n<\/pre>\nnext, we will create some django models in books\/models.py<\/strong><\/p>\nfrom django.db import models<\/code>\n\n# Create your models here.\nclass Category(models.Model):\nname = models.CharField(max_length=100)\n\ndef __str__(self):\nreturn self.name\n\nclass Book(models.Model):\nname = models.CharField(max_length=100)\nauthor = models.CharField(max_length=100)\ncategory = models.ForeignKey(Category, related_name='books')\n\ndef __str__(self):\nreturn self.name\n<\/pre>\nThe following part is where we will set up our GraphQL backend. create a schema.py<\/strong> in books<\/strong>
\nschema.py<\/strong> is synonymous to urls.py in a django project. In this file, we will define how our queries will be handled by the GraphQL backend. we will start with simple queries like list and retrieve. Later in the article, I will touch on how to use mutation<\/strong> to do create\/update\/delete operations.<\/p>\nfrom graphene import AbstractType\nfrom graphene import Field\nfrom graphene import Node\nfrom graphene import ClientIDMutation\nfrom graphene import String\nfrom graphene import Float\n\nfrom graphene_django.filter import DjangoFilterConnectionField\nfrom graphene_django.types import DjangoObjectType\n\nfrom .models import Category\nfrom .models import Book\n\nclass CategoryNode(DjangoObjectType):\n class Meta:\n model = Category\n interfaces = (Node, )\n filter_fields = ['name', 'books']\n filter_order_by = ('name')\n\n\nclass BookNode(DjangoObjectType):\n class Meta:\n model = Book\n interfaces = (Node, )\n filter_fields = {\n 'name': ['exact', 'icontains', 'istartswith'],\n 'author': ['exact', 'icontains'],\n 'category': ['exact'],\n 'category__name': ['exact'],\n }\n filter_order_by = ('name', 'category__name')\n\nclass CategoryQuery(AbstractType):\n category = DjangoFilterConnectionField(CategoryNode)\n \nclass BookQuery(AbstractType):\n book = Node.Field(BookNode)\n all_books = DjangoFilterConnectionField(BookNode)\n<\/code><\/pre>\nLet me briefly explain what is actually happening here. In the schema.py found in the app, we have defined 2 Node classes, BookNode and CategoryNode. If you are familiar with django RESTful framework, they are pretty similar to serializer. In the Meta class of BookNode and CategoryNode, you can see that several options has been indicated to define the behaviour that is supported when queried. There are additional options like exclude_field<\/strong> and only_field<\/strong>. You may dig through the source code<\/a> of graphene for more information.<\/p>\nAfter defining the Node Classes, we will need to consolidate them into a Query class that is of type AbstractType. The reason why this is AbstractType is to allow inheritance later by the Root Query class. the snake_case in the BookQuery and CategoryQuery will be transformed into camelCase. So in your query, you will refer to allBooks instead of all_books.<\/p>\n
Next, we will create a root schema in the catalog folder. catalog\/schema.py<\/strong><\/p>\nimport graphene\nfrom books.schema import BookQuery\nfrom books.schema import CategoryQuery\n\nclass RootQuery(BookQuery\n , CategoryQuery\n , graphene.ObjectType):\n pass\n\nschema = graphene.Schema(query=RootQuery)<\/code><\/pre>\nNext we will need to enable GraphQL in our project. This is achieved by changing the django project settings.
\nOpen catalog\/settings.py and add the following to the file.<\/p>\n
\nINSTALLED_APPS = (\n ...\n 'books',\n 'graphene_django',\n)\n\nGRAPHENE = {\n 'SCHEMA' : 'catalog.schema.schema', #points to the schema variable in schema.py\n 'SCHEMA_INDENT': 2, #defines the indentation space in the output\n}<\/code><\/pre>\n