mirror of
https://github.com/graphql-python/graphene-django.git
synced 2024-11-25 19:14:11 +03:00
270 lines
7.0 KiB
ReStructuredText
270 lines
7.0 KiB
ReStructuredText
Queries & ObjectTypes
|
|
=====================
|
|
|
|
Introduction
|
|
------------
|
|
|
|
Graphene-Django offers a host of features for performing GraphQL queries.
|
|
|
|
Graphene-Django ships with a special ``DjangoObjectType`` that automatically transforms a Django Model
|
|
into a ``ObjectType`` for you.
|
|
|
|
|
|
Full example
|
|
~~~~~~~~~~~~
|
|
|
|
.. code:: python
|
|
|
|
# my_app/schema.py
|
|
|
|
import graphene
|
|
|
|
from graphene_django.types import DjangoObjectType
|
|
from .models import Question
|
|
|
|
|
|
class QuestionType(DjangoObjectType):
|
|
class Meta:
|
|
model = Question
|
|
|
|
|
|
class Query:
|
|
questions = graphene.List(QuestionType)
|
|
question = graphene.Field(Question, question_id=graphene.String())
|
|
|
|
def resolve_questions(self, info, **kwargs):
|
|
# Querying a list
|
|
return Question.objects.all()
|
|
|
|
def resolve_question(self, info, question_id):
|
|
# Querying a single question
|
|
return Question.objects.get(pk=question_id)
|
|
|
|
|
|
Fields
|
|
------
|
|
|
|
By default, ``DjangoObjectType`` will present all fields on a Model through GraphQL.
|
|
If you don't want to do this you can change this by setting either ``only_fields`` and ``exclude_fields``.
|
|
|
|
only_fields
|
|
~~~~~~~~~~~
|
|
|
|
Show **only** these fields on the model:
|
|
|
|
.. code:: python
|
|
|
|
class QuestionType(DjangoObjectType):
|
|
class Meta:
|
|
model = Question
|
|
only_fields = ('question_text')
|
|
|
|
|
|
exclude_fields
|
|
~~~~~~~~~~~~~~
|
|
|
|
Show all fields **except** those in ``exclude_fields``:
|
|
|
|
.. code:: python
|
|
|
|
class QuestionType(DjangoObjectType):
|
|
class Meta:
|
|
model = Question
|
|
exclude_fields = ('question_text')
|
|
|
|
|
|
Customised fields
|
|
~~~~~~~~~~~~~~~~~
|
|
|
|
You can completely overwrite a field, or add new fields, to a ``DjangoObjectType`` using a Resolver:
|
|
|
|
.. code:: python
|
|
|
|
class QuestionType(DjangoObjectType):
|
|
|
|
class Meta:
|
|
model = Question
|
|
exclude_fields = ('question_text')
|
|
|
|
extra_field = graphene.String()
|
|
|
|
def resolve_extra_field(self, info):
|
|
return 'hello!'
|
|
|
|
|
|
Related models
|
|
--------------
|
|
|
|
Say you have the following models:
|
|
|
|
.. code:: python
|
|
|
|
class Category(models.Model):
|
|
foo = models.CharField(max_length=256)
|
|
|
|
class Question(models.Model):
|
|
category = models.ForeignKey(Category, on_delete=models.CASCADE)
|
|
|
|
|
|
When ``Question`` is published as a ``DjangoObjectType`` and you want to add ``Category`` as a query-able field like so:
|
|
|
|
.. code:: python
|
|
|
|
class QuestionType(DjangoObjectType):
|
|
class Meta:
|
|
model = Question
|
|
only_fields = ('category',)
|
|
|
|
Then all query-able related models must be defined as DjangoObjectType subclass,
|
|
or they will fail to show if you are trying to query those relation fields. You only
|
|
need to create the most basic class for this to work:
|
|
|
|
.. code:: python
|
|
|
|
class CategoryType(DjangoObjectType):
|
|
class Meta:
|
|
model = Category
|
|
|
|
Default QuerySet
|
|
-----------------
|
|
|
|
If you are using ``DjangoObjectType`` you can define a custom `get_queryset` method.
|
|
Use this to control filtering on the ObjectType level instead of the Query object level.
|
|
|
|
.. code:: python
|
|
|
|
from graphene_django.types import DjangoObjectType
|
|
from .models import Question
|
|
|
|
|
|
class QuestionType(DjangoObjectType):
|
|
class Meta:
|
|
model = Question
|
|
|
|
@classmethod
|
|
def get_queryset(cls, queryset, info):
|
|
if info.context.user.is_anonymous:
|
|
return queryset.filter(published=True)
|
|
return queryset
|
|
|
|
Resolvers
|
|
---------
|
|
|
|
When a GraphQL query is received by the ``Schema`` object, it will map it to a "Resolver" related to it.
|
|
|
|
This resolve method should follow this format:
|
|
|
|
.. code:: python
|
|
|
|
def resolve_foo(self, info, **kwargs):
|
|
|
|
Where "foo" is the name of the field declared in the ``Query`` object.
|
|
|
|
.. code:: python
|
|
|
|
class Query:
|
|
foo = graphene.List(QuestionType)
|
|
|
|
def resolve_foo(self, info, **kwargs):
|
|
id = kwargs.get('id')
|
|
return QuestionModel.objects.get(id)
|
|
|
|
Arguments
|
|
~~~~~~~~~
|
|
|
|
Additionally, Resolvers will receive **any arguments declared in the field definition**. This allows you to provide input arguments in your GraphQL server and can be useful for custom queries.
|
|
|
|
.. code:: python
|
|
|
|
class Query:
|
|
question = graphene.Field(Question, foo=graphene.String(), bar=graphene.Int())
|
|
|
|
def resolve_question(self, info, foo, bar):
|
|
# If `foo` or `bar` are declared in the GraphQL query they will be here, else None.
|
|
return Question.objects.filter(foo=foo, bar=bar).first()
|
|
|
|
|
|
Info
|
|
~~~~
|
|
|
|
The ``info`` argument passed to all resolve methods holds some useful information.
|
|
For Graphene-Django, the ``info.context`` attribute is the ``HTTPRequest`` object
|
|
that would be familiar to any Django developer. This gives you the full functionality
|
|
of Django's ``HTTPRequest`` in your resolve methods, such as checking for authenticated users:
|
|
|
|
.. code:: python
|
|
|
|
def resolve_questions(self, info, **kwargs):
|
|
# See if a user is authenticated
|
|
if info.context.user.is_authenticated():
|
|
return Question.objects.all()
|
|
else:
|
|
return Question.objects.none()
|
|
|
|
|
|
Plain ObjectTypes
|
|
-----------------
|
|
|
|
With Graphene-Django you are not limited to just Django Models - you can use the standard
|
|
``ObjectType`` to create custom fields or to provide an abstraction between your internal
|
|
Django models and your external API.
|
|
|
|
.. code:: python
|
|
|
|
import graphene
|
|
from .models import Question
|
|
|
|
|
|
class MyQuestion(graphene.ObjectType):
|
|
text = graphene.String()
|
|
|
|
|
|
class Query:
|
|
question = graphene.Field(MyQuestion, question_id=graphene.String())
|
|
|
|
def resolve_question(self, info, question_id):
|
|
question = Question.objects.get(pk=question_id)
|
|
return MyQuestion(
|
|
text=question.question_text
|
|
)
|
|
|
|
For more information and more examples, please see the `core object type documentation <https://docs.graphene-python.org/en/latest/types/objecttypes/>`__.
|
|
|
|
|
|
Relay
|
|
-----
|
|
|
|
`Relay <http://docs.graphene-python.org/en/latest/relay/>`__ with Graphene-Django gives us some additional features:
|
|
|
|
- Pagination and slicing.
|
|
- An abstract ``id`` value which contains enough info for the server to know its type and its id.
|
|
|
|
There is one additional import and a single line of code needed to adopt this:
|
|
|
|
Full example
|
|
~~~~~~~~~~~~
|
|
|
|
.. code:: python
|
|
|
|
from graphene import relay
|
|
from graphene_django import DjangoObjectType
|
|
from .models import Question
|
|
|
|
|
|
class QuestionType(DjangoObjectType):
|
|
class Meta:
|
|
model = Question
|
|
interaces = (relay.Node,)
|
|
|
|
|
|
class QuestionConnection(relay.Connection):
|
|
class Meta:
|
|
node = QuestionType
|
|
|
|
|
|
class Query:
|
|
question = graphene.Field(QuestionType)
|
|
questions = relay.ConnectionField(QuestionConnection)
|
|
|
|
See the `Relay documentation <https://docs.graphene-python.org/en/latest/relay/nodes/>`__ on
|
|
the core graphene pages for more information on customing the Relay experience. |