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394 lines
10 KiB
ReStructuredText
394 lines
10 KiB
ReStructuredText
Basic Tutorial
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===========================================
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Graphene Django has a number of additional features that are designed to make
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working with Django easy. Our primary focus in this tutorial is to give a good
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understanding of how to connect models from Django ORM to Graphene object types.
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Set up the Django project
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-------------------------
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We will set up the project, create the following:
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- A Django project called ``cookbook``
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- An app within ``cookbook`` called ``ingredients``
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.. code:: bash
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# Create the project directory
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mkdir cookbook
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cd cookbook
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# Create a virtualenv to isolate our package dependencies locally
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virtualenv env
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source env/bin/activate # On Windows use `env\Scripts\activate`
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# Install Django and Graphene with Django support
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pip install django graphene_django
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# Set up a new project with a single application
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django-admin startproject cookbook . # Note the trailing '.' character
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cd cookbook
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django-admin startapp ingredients
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Now sync your database for the first time:
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.. code:: bash
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python manage.py migrate
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Let's create a few simple models...
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Defining our models
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^^^^^^^^^^^^^^^^^^^
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Let's get started with these models:
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.. code:: python
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# cookbook/ingredients/models.py
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from django.db import models
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class Category(models.Model):
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name = models.CharField(max_length=100)
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def __str__(self):
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return self.name
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class Ingredient(models.Model):
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name = models.CharField(max_length=100)
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notes = models.TextField()
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category = models.ForeignKey(
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Category, related_name="ingredients", on_delete=models.CASCADE
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)
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def __str__(self):
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return self.name
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Add ingredients as INSTALLED_APPS:
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.. code:: python
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# cookbook/settings.py
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INSTALLED_APPS = [
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...
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# Install the ingredients app
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"cookbook.ingredients",
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]
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Don't forget to create & run migrations:
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.. code:: bash
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python manage.py makemigrations
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python manage.py migrate
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Load some test data
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^^^^^^^^^^^^^^^^^^^
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Now is a good time to load up some test data. The easiest option will be
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to `download the
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ingredients.json <https://raw.githubusercontent.com/graphql-python/graphene-django/master/examples/cookbook/cookbook/ingredients/fixtures/ingredients.json>`__
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fixture and place it in
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``cookbook/ingredients/fixtures/ingredients.json``. You can then run the
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following:
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.. code:: bash
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python manage.py loaddata ingredients
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Installed 6 object(s) from 1 fixture(s)
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Alternatively you can use the Django admin interface to create some data
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yourself. You'll need to run the development server (see below), and
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create a login for yourself too (``python manage.py createsuperuser``).
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Register models with admin panel:
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.. code:: python
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# cookbook/ingredients/admin.py
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from django.contrib import admin
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from cookbook.ingredients.models import Category, Ingredient
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admin.site.register(Category)
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admin.site.register(Ingredient)
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Hello GraphQL - Schema and Object Types
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---------------------------------------
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In order to make queries to our Django project, we are going to need few things:
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* Schema with defined object types
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* A view, taking queries as input and returning the result
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GraphQL presents your objects to the world as a graph structure rather
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than a more hierarchical structure to which you may be accustomed. In
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order to create this representation, Graphene needs to know about each
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*type* of object which will appear in the graph.
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This graph also has a *root type* through which all access begins. This
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is the ``Query`` class below.
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To create GraphQL types for each of our Django models, we are going to subclass the ``DjangoObjectType`` class which will automatically define GraphQL fields that correspond to the fields on the Django models.
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After we've done that, we will list those types as fields in the ``Query`` class.
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Create ``cookbook/schema.py`` and type the following:
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.. code:: python
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# cookbook/schema.py
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import graphene
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from graphene_django import DjangoObjectType
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from cookbook.ingredients.models import Category, Ingredient
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class CategoryType(DjangoObjectType):
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class Meta:
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model = Category
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fields = ("id", "name", "ingredients")
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class IngredientType(DjangoObjectType):
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class Meta:
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model = Ingredient
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fields = ("id", "name", "notes", "category")
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class Query(graphene.ObjectType):
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all_ingredients = graphene.List(IngredientType)
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category_by_name = graphene.Field(CategoryType, name=graphene.String(required=True))
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def resolve_all_ingredients(root, info):
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# We can easily optimize query count in the resolve method
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return Ingredient.objects.select_related("category").all()
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def resolve_category_by_name(root, info, name):
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try:
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return Category.objects.get(name=name)
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except Category.DoesNotExist:
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return None
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schema = graphene.Schema(query=Query)
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You can think of this as being something like your top-level ``urls.py``
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file.
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Testing everything so far
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-------------------------
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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.
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Update settings
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^^^^^^^^^^^^^^^
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Next, install your app and GraphiQL in your Django project. GraphiQL is
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a web-based integrated development environment to assist in the writing
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and executing of GraphQL queries. It will provide us with a simple and
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easy way of testing our cookbook project.
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Add ``graphene_django`` to ``INSTALLED_APPS`` in ``cookbook/settings.py``:
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.. code:: python
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# cookbook/settings.py
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INSTALLED_APPS = [
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...
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"graphene_django",
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]
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And then add the ``SCHEMA`` to the ``GRAPHENE`` config in ``cookbook/settings.py``:
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.. code:: python
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# cookbook/settings.py
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GRAPHENE = {
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"SCHEMA": "cookbook.schema.schema"
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}
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Alternatively, we can specify the schema to be used in the urls definition,
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as explained below.
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Creating GraphQL and GraphiQL views
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^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
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Unlike a RESTful API, there is only a single URL from which GraphQL is
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accessed. Requests to this URL are handled by Graphene's ``GraphQLView``
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view.
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This view will serve as GraphQL endpoint. As we want to have the
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aforementioned GraphiQL we specify that on the parameters with ``graphiql=True``.
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.. code:: python
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# cookbook/urls.py
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from django.contrib import admin
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from django.urls import path
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from django.views.decorators.csrf import csrf_exempt
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from graphene_django.views import GraphQLView
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urlpatterns = [
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path("admin/", admin.site.urls),
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path("graphql", csrf_exempt(GraphQLView.as_view(graphiql=True))),
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]
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If we didn't specify the target schema in the Django settings file
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as explained above, we can do so here using:
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.. code:: python
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# cookbook/urls.py
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from django.contrib import admin
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from django.urls import path
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from django.views.decorators.csrf import csrf_exempt
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from graphene_django.views import GraphQLView
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from cookbook.schema import schema
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urlpatterns = [
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path("admin/", admin.site.urls),
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path("graphql", csrf_exempt(GraphQLView.as_view(graphiql=True, schema=schema))),
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]
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Testing our GraphQL schema
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^^^^^^^^^^^^^^^^^^^^^^^^^^
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We're now ready to test the API we've built. Let's fire up the server
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from the command line.
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.. code:: bash
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python manage.py runserver
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Performing system checks...
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Django version 3.0.7, using settings 'cookbook.settings'
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Starting development server at http://127.0.0.1:8000/
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Quit the server with CONTROL-C.
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Go to `localhost:8000/graphql <http://localhost:8000/graphql>`__ and
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type your first query!
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.. code::
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query {
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allIngredients {
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id
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name
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}
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}
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If you are using the provided fixtures, you will see the following response:
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.. code::
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{
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"data": {
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"allIngredients": [
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{
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"id": "1",
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"name": "Eggs"
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},
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{
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"id": "2",
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"name": "Milk"
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},
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{
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"id": "3",
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"name": "Beef"
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},
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{
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"id": "4",
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"name": "Chicken"
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}
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]
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}
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}
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Congratulations, you have created a working GraphQL server 🥳!
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Note: Graphene `automatically camelcases <http://docs.graphene-python.org/en/latest/types/schema/#auto-camelcase-field-names>`__ all field names for better compatibility with JavaScript clients.
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Getting relations
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-----------------
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Using the current schema we can query for relations too. This is where GraphQL becomes really powerful!
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For example, we may want to get a specific categories and list all ingredients that are in that category.
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We can do that with the following query:
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.. code::
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query {
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categoryByName(name: "Dairy") {
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id
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name
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ingredients {
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id
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name
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}
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}
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}
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This will give you (in case you are using the fixtures) the following result:
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.. code::
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{
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"data": {
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"categoryByName": {
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"id": "1",
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"name": "Dairy",
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"ingredients": [
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{
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"id": "1",
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"name": "Eggs"
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},
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{
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"id": "2",
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"name": "Milk"
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}
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]
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}
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}
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}
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We can also list all ingredients and get information for the category they are in:
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.. code::
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query {
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allIngredients {
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id
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name
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category {
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id
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name
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}
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}
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}
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Summary
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-------
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As you can see, GraphQL is very powerful and integrating Django models allows you to get started with a working server quickly.
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If you want to put things like ``django-filter`` and automatic pagination in action, you should continue with the :ref:`Relay tutorial`.
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A good idea is to check the `Graphene <http://docs.graphene-python.org/en/latest/>`__
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documentation so that you are familiar with it as well.
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