Django Graphene

Slides

Recording

Setup

1. Install Django Graphene

   pip install graphene-django

   settings.py

   INSTALLED_APPS = [
       ...
       'django.contrib.staticfiles', # Required for GraphiQL
       'graphene_django'
   ]

2. Add a GraphQL url

   from django.views.decorators.csrf import csrf_exempt
   from graphene_django.views import GraphQLView
   
   urlpatterns = [
       ...
       path("graphql/", csrf_exempt(GraphQLView.as_view(graphiql=True))),
   ]

3. Add an empty Query

   schema.py

   import graphene
   
   class Query(graphene.ObjectType):
       pass
   
   schema = graphene.Schema(query=Query)

   settings.py

   GRAPHENE = {
     'SCHEMA': 'graphene_demo.schema.schema'
   }

Basics

4. Add some fields to the query

   class Query(graphene.ObjectType):
     hello = graphene.String()
     goodbye = graphene.String()

5. Add resolvers for the fields

   class Query(graphene.ObjectType):
     hello = graphene.String()
     goodbye = graphene.String()
   
     def resolve_hello(self, info):
         return "Hello world!"
   
     def resolve_goodbye(self, info):
         return "Goodbye cruel world!"

6. Make a field and resolver with parameters

   class Query(graphene.ObjectType):
     hello = graphene.String(name=graphene.String(default_value="world"))
     goodbye = graphene.String()
   
     def resolve_hello(self, info, name):
         return f"Hello {name}!"
   
     def resolve_goodbye(self, info):
         return "Goodbye cruel world!"

Django Specific

7. Make an application schema and connect it to the main schema

   bootcamps/schema.py

   from datetime import datetime
   import graphene
   
    class Query(object):
      thing = graphene.Date()
   
      def resolve_thing(parent, info):
        return datetime.now()

   schema.py

   import bootcamps.schema
   
   class Query(bootcamps.schema.Query, graphene.ObjectType):
     ...

8. Create our first type

   bootcamps/schema.py

   from graphene_django import DjangoObjectType
   
   from .models import Instructor

   class InstructorType(DjangoObjectType): class Meta: model = Instructor

9. Add an instructors query

   class Query(object):
     ...
     instructors = graphene.List(InstructorType)
   
     ...
   
     def resolve_instructors(self, info):
         return Instructor.objects.all()

10. Add a single instructor query

    class Query(object):
     ...
     instructor = graphene.Field(InstructorType, id=graphene.Int())
    
     ...
    
     def resolve_instructor(self, info, id):
        if id is not None:
            return Instructor.objects.get(pk=id)
        return None

11. Simplify using DjangoListField

    from graphene_django import DjangoObjectType, DjangoListField
    
    ...
    
    class Query(object):
    
      instructors = DjangoListField(InstructorType)
    
          def resolve_thing(self, info):
              ...
    
          # resolver can be deleted
          # def resolve_instructors(self, infor):
    
          def resolve_instructor(self, info, id):
              ...

12. Automagic Relationships! 💖

    from .models import Instructor, Cohort
    
    class CohortType(DjangoObjectType):
      class Meta:
          model = Cohort