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359 lines
9.7 KiB
ReStructuredText
359 lines
9.7 KiB
ReStructuredText
.. _Relay tutorial:
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Relay tutorial
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========================================
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Graphene has a number of additional features that are designed to make
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working with Django *really simple*.
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Note: The code in this quickstart is pulled from the `cookbook example
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app <https://github.com/graphql-python/graphene-django/tree/main/examples/cookbook>`__.
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A good idea is to check the following things first:
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* `Graphene Relay documentation <http://docs.graphene-python.org/en/latest/relay/>`__
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* `GraphQL Relay Specification <https://relay.dev/docs/guides/graphql-server-specification/>`__
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Setup the Django project
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------------------------
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We will setup 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
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pip install graphene_django
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# Set up a new project with a single application
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django-admin.py startproject cookbook . # Note the trailing '.' character
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cd cookbook
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django-admin.py 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(Category, related_name='ingredients', on_delete=models.CASCADE)
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def __str__(self):
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return self.name
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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/main/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 (``./manage.py createsuperuser``).
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Schema
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------
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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. In this example, we provide the ability to
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list all ingredients via ``all_ingredients``, and the ability to obtain
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a specific ingredient via ``ingredient``.
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Create ``cookbook/ingredients/schema.py`` and type the following:
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.. code:: python
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# cookbook/ingredients/schema.py
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from graphene import relay, ObjectType
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from graphene_django import DjangoObjectType
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from graphene_django.filter import DjangoFilterConnectionField
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from ingredients.models import Category, Ingredient
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# Graphene will automatically map the Category model's fields onto the CategoryNode.
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# This is configured in the CategoryNode's Meta class (as you can see below)
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class CategoryNode(DjangoObjectType):
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class Meta:
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model = Category
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fields = '__all__'
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filter_fields = ['name', 'ingredients']
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interfaces = (relay.Node, )
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class IngredientNode(DjangoObjectType):
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class Meta:
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model = Ingredient
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fields = '__all__'
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# Allow for some more advanced filtering here
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filter_fields = {
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'name': ['exact', 'icontains', 'istartswith'],
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'notes': ['exact', 'icontains'],
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'category': ['exact'],
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'category__name': ['exact'],
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}
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interfaces = (relay.Node, )
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class Query(ObjectType):
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category = relay.Node.Field(CategoryNode)
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all_categories = DjangoFilterConnectionField(CategoryNode)
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ingredient = relay.Node.Field(IngredientNode)
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all_ingredients = DjangoFilterConnectionField(IngredientNode)
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The filtering functionality is provided by
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`django-filter <https://django-filter.readthedocs.org>`__. See the
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`usage
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documentation <https://django-filter.readthedocs.org/en/latest/guide/usage.html#the-filter>`__
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for details on the format for ``filter_fields``. While optional, this
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tutorial makes use of this functionality so you will need to install
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``django-filter`` for this tutorial to work:
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.. code:: bash
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pip install django-filter
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Note that the above ``Query`` class is marked as 'abstract'. This is
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because we will now create a project-level query which will combine all
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our app-level queries.
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Create the parent project-level ``cookbook/schema.py``:
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.. code:: python
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import graphene
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import ingredients.schema
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class Query(ingredients.schema.Query, graphene.ObjectType):
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# This class will inherit from multiple Queries
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# as we begin to add more apps to our project
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pass
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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 (although it currently lacks any namespacing).
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Testing everything so far
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-------------------------
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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 ``ingredients`` and ``graphene_django`` to ``INSTALLED_APPS`` in ``cookbook/settings.py``:
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.. code:: python
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INSTALLED_APPS = [
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...
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# This will also make the `graphql_schema` management command available
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'graphene_django',
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# Install the ingredients app
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'ingredients',
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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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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 params with ``graphiql=True``.
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.. code:: python
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from django.conf.urls import url, include
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from django.contrib import admin
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from graphene_django.views import GraphQLView
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urlpatterns = [
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url(r'^admin/', admin.site.urls),
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url(r'^graphql$', GraphQLView.as_view(graphiql=True)),
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]
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If we didn't specify the target schema in the Django settings file
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as explained above, we can do so here using:
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.. code:: python
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from django.conf.urls import url, include
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from django.contrib import admin
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from graphene_django.views import GraphQLView
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from cookbook.schema import schema
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urlpatterns = [
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url(r'^admin/', admin.site.urls),
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url(r'^graphql$', 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 3.1.7, 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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edges {
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node {
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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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}
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The above will return the names & IDs for all ingredients. But perhaps
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you want a specific ingredient:
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.. code::
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query {
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# Graphene creates globally unique IDs for all objects.
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# You may need to copy this value from the results of the first query
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ingredient(id: "SW5ncmVkaWVudE5vZGU6MQ==") {
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name
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}
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}
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You can also get each ingredient for each category:
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.. code::
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query {
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allCategories {
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edges {
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node {
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name,
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ingredients {
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edges {
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node {
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name
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}
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}
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}
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}
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}
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}
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}
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Or you can get only 'meat' ingredients containing the letter 'e':
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.. code::
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query {
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# You can also use `category: "CATEGORY GLOBAL ID"`
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allIngredients(name_Icontains: "e", category_Name: "Meat") {
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edges {
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node {
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name
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}
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}
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}
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}
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Final Steps
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^^^^^^^^^^^
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We have created a GraphQL endpoint that will work with Relay, but for Relay to work it needs access to a (non python) schema. Instructions to export the schema can be found on the `Introspection Schema <http://docs.graphene-python.org/projects/django/en/latest/introspection/>`__ part of this guide.
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