GraphQL with Python frameworks GraphQL with Python frameworks - - PowerPoint PPT Presentation

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GraphQL with Python frameworks GraphQL with Python frameworks - - PowerPoint PPT Presentation

Feb 05, 2023 13 likes •574 views

27.09.2018 reveal.js GraphQL with Python frameworks GraphQL with Python frameworks Create next-generation API with ease Bartosz Kazua http://0.0.0.0:8080/?print-pdf 1/56 27.09.2018 reveal.js About About mua mua Frontend/Backend/Mobile

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GraphQL with Python frameworks GraphQL with Python frameworks

Create next-generation API with ease Bartosz Kazuła

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About About mua mua

Frontend/Backend/Mobile developer Software architect Highly focused on new technologies

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What is GraphQL? What is GraphQL?

A query language for your API

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How it works How it works

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How it works How it works

Database

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How it works How it works

Database REST API

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How it works How it works

Database REST API Legacy API

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Is it production ready? Is it production ready?

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Data structures Data structures

Schema Type Query Mutation

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Schema Schema

Entrypoint to API, defines queries and mutations that can be accessed via GraphQL

type Schema { query: Query mutation: Mutation }

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Type Type

The most basic components of a GraphQL schema, which just represent a kind of object you can fetch from your service, and what fields it has

type Character { name: String! appearsIn: [Episode]! }

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Query Query

Asking for fields and objects based on provided parameters. Here you can define the shape of response.

{ hero { name } }

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Mutation Mutation

The way to modify data. If the mutation field returns an object type, you can ask for nested fields.

mutation CreateReviewForEpisode($ep: Episode!, $review: ReviewInput!) { createReview(episode: $ep, review: $review) { stars commentary } }

{ "ep": "JEDI", "review": { "stars": 5, "commentary": "This is a great movie!" } }

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GraphiQL GraphiQL

A graphical interactive in-browser GraphQL IDE for testing and writing queries.

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Graphene Graphene

GraphQL in Python made easy GraphQL in Python made easy

https://graphene-python.org/

pip install graphene

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Let's build some API Let's build some API

Add user / get user / get all users Add blog post / get post / get all posts

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Django Django

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pip install graphene graphene-django

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pip install graphene graphene-django INSTALLED_APPS = ( # ... 'graphene_django', ) GRAPHENE = { 'SCHEMA': 'app.schema.schema' # Path to main schema }

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pip install graphene graphene-django INSTALLED_APPS = ( # ... 'graphene_django', ) GRAPHENE = { 'SCHEMA': 'app.schema.schema' # Path to main schema }

from django.urls import path from graphene_django.views import GraphQLView urlpatterns = [ # ... path('graphql/', GraphQLView.as_view(graphiql=True)), ]

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User model User model

class User(models.Model): name = models.CharField(max_length=20) surname = models.CharField(max_length=30) age = models.IntegerField()

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User model User model UserType UserType

class User(models.Model): name = models.CharField(max_length=20) surname = models.CharField(max_length=30) age = models.IntegerField() from graphene_django import DjangoObjectType class UserType(DjangoObjectType): class Meta: model = User

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User Query User Query

class UserQuery(graphene.ObjectType): users = graphene.List(UserType) def resolve_users(self, info): return User.objects.all()

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Schema Schema

schema = graphene.Schema(query=UserQuery) app/schema.py

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Getting one user Getting one user

class UserQuery(graphene.ObjectType): users = graphene.List(UserType) user = graphene.Field(UserType, name=graphene.String()) def resolve_users(self, info): return User.objects.all() def resolve_user(self, info, name): return User.objects.filter(name=name).first()

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Getting one user Getting one user

class UserQuery(graphene.ObjectType): users = graphene.List(UserType) user = graphene.Field(UserType, name=graphene.String()) def resolve_users(self, info): return User.objects.all() def resolve_user(self, info, name): return User.objects.filter(name=name).first()

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Getting one user Getting one user

class UserQuery(graphene.ObjectType): users = graphene.List(UserType) user = graphene.Field(UserType, name=graphene.String()) def resolve_users(self, info): return User.objects.all() def resolve_user(self, info, name): return User.objects.filter(name=name).first()

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User mutation User mutation

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Plain GraphQL mutation Plain GraphQL mutation

class UserMutation(graphene.Mutation): user = graphene.Field(UserType) class Arguments: name = graphene.String() surname = graphene.String() age = graphene.Int() def mutate(self, info, **kwargs): user = User.objects.create(**kwargs) return UserMutation(user=user)

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Add mutation to the schema Add mutation to the schema

class Mutations(graphene.ObjectType): create_user = UserMutation.Field() schema = graphene.Schema(query=UserQuery, mutation=Mutations)

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Add mutation to the schema Add mutation to the schema

class Mutations(graphene.ObjectType): create_user = UserMutation.Field() schema = graphene.Schema(query=UserQuery, mutation=Mutations)

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Django Forms-based mutation Django Forms-based mutation

class UserForm(forms.ModelForm): class Meta: model = User fields = ('name', 'surname', 'age') class UserMutation(DjangoModelFormMutation): class Meta: form_class = UserForm

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Django FAQ Django FAQ

I use REST Framework - how to live? Take a look at graphene_django.rest_framework package. How to validate data? When using forms - use built-in validation. When going plain - add your own validator. How to receive user data? Use info.context variable passed to every function.

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GraphQL with Django GraphQL with Django Q&A Q&A

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Flask Flask

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Installation Installation

pip install graphene graphene_sqlalchemy Flask-GraphQL app.add_url_rule( '/graphql', view_func=GraphQLView.as_view( 'graphql', schema=schema, graphiql=True ) )

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Post model Post model

class Post(Model): __tablename__ = 'posts' id = Column(Integer, primary_key=True) name = Column(String) intro = Column(Text) content = Column(Text) author = Column(String)

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Type and query Type and query

class PostType(SQLAlchemyObjectType): class Meta: model = Post

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Type and query Type and query

class PostType(SQLAlchemyObjectType): class Meta: model = Post class Query(graphene.ObjectType): posts = graphene.List(PostType) def resolve_posts(self, info): return Post.query.all()

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Get one post Get one post

class Query(graphene.ObjectType): posts = graphene.List(PostType) post = graphene.Field(PostType, id=graphene.Int()) def resolve_posts(self, info): return Post.query.all() def resolve_post(self, info, id): return Post.query.get(id)

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Get one post Get one post

class Query(graphene.ObjectType): posts = graphene.List(PostType) post = graphene.Field(PostType, id=graphene.Int()) def resolve_posts(self, info): return Post.query.all() def resolve_post(self, info, id): return Post.query.get(id)

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A mutation has no helpers ☹ A mutation has no helpers ☹

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Create post mutation Create post mutation

class CreatePost(graphene.Mutation): post = graphene.Field(PostType) class Arguments: name = graphene.String() intro = graphene.String() content = graphene.String() author = graphene.String() def mutate(self, info, **kwargs): post = Post(**kwargs) db_session.add(post) db_session.commit()

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Add mutation to schema Add mutation to schema

class Mutations(graphene.ObjectType): create_post = CreatePost.Field() schema = graphene.Schema(query=Query, mutation=Mutations)

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FAQ FAQ

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How to handle errors? How to handle errors?

Check out the "errors" list next to data. If it has some errors then handle them. You can customize your GraphQLView to handle errors differently.

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Best authorization approach? Best authorization approach?

There are two:

  • 1. Private & public GraphQL endpoints ( BAD!)
  • 2. Login required decorator wrapping classes/methods
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How to limit database calls? How to limit database calls?

Read about batching queries.

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Thanks for watching Thanks for watching

Bartosz Kazuła Bartosz Kazuła

bkazula bartosz@kazula.eu

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