Introduction to GraphQL

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GET https://2017.es.pycon.org/speakers/me { "name": "Adrián Matellanes", "roles": [ "Lead API Developer", "Málaga Python Organizer" ], "worksAt": "Ebury", "twitter": "@_amatellanes", "github": "github.com/amatellanes" }

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What’s GraphQL?

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A programming language

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A special type of database

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A library

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A Query Language for APIs

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Why GraphQL?

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Due to the nature of REST

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REST Problems

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GET /characters/1 { "name": "Jon Snow" }

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"url": "http://anapioficeandfire.com/api/characters/583", "name": "Jon Snow", "culture": "Northmen", "born": "In 283 AC", "titles": [ "Lord Commander of the Night's Watch" ], "aliases": [ "Lord Snow", "Ned Stark's Bastard", "The Snow of Winterfell", "The Bastard of Winterfell", "Lord Crow" ], "allegiances": [ "http://anapioficeandfire.com/api/houses/362" ], "books": [ "http://anapioficeandfire.com/api/books/5" ], "povBooks": [ "http://anapioficeandfire.com/api/books/1", "http://anapioficeandfire.com/api/books/2", "http://anapioficeandfire.com/api/books/3", "http://anapioficeandfire.com/api/books/8"

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Round Trip and Repeat Trip Times

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/episodes/1

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/episodes/1 /characters/345 /characters/563 /characters/802 /characters/441 /characters/674

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/episodes/1 /characters/345 /characters/563 /characters/802 /characters/441 /characters/674 /reviews/3512

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Over/Under Fetching

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/episodes/1?fields=characters(name,playedBy)

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/episode_with_all_stuff /episode_with_amazing_pictures /episode_with_stuff_i_need_today /episode_with_stuff_for_mobile_app /episode_with_actors_and_reviews_and_images /episode_with_stuff_for_mobile_app_v2 /episode_with_actors_and_reviews_but_no_images

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/episode_with_all_stuff /episode_with_amazing_pictures /episode_with_stuff_i_need_today /episode_with_stuff_for_mobile_app /episode_with_stuff_for_mobile_app_v2 /episode_with_actors_and_reviews_and_images /episode_with_actors_and_reviews_but_no_images

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https://code.facebook.com/projects/

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Created July 1, 2015 Updated September 20, 2017 381 Forks 6,078 Stars 302 Commits 82 Open Issues https://github.com/facebook/graphql

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“You will receive what you ask for no more, no less.” - Mark Allen

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GraphQL vs. REST

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REST Model

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Client /books /characters /houses Databases Services External APIs

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GraphQL Model

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Client Databases Services External APIs /graphql/

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Anatomy of a GraphQL

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{ me { name } }

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{ me { name } } { "me": { "name": "Jon Snow" } }

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Scalar types

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Int Float String Boolean ID Date enum

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GraphQL Schema Definition Language

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type Query { allCharacters: [Character]! character(id: ID!): Character }

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type Query { allCharacters: [Character]! character(id: ID!): Character } Root Type

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type Query { allCharacters: [Character]! character(id: ID!): Character } Root Fields

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type Query { allCharacters: [Character]! character(id: ID!): Character } Arguments

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type Query { allCharacters: [Character]! character(id: ID!): Character } Return Types

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type Character { name: String! house: House! } type House { name: String! words: String! members: [Character]! }

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type Character { name: String! house: House! } type House { name: String! words: String! members: [Character]! } Object Type

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type Character { name: String! house: House! } type House { name: String! words: String! members: [Character]! } Fields

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type Character { name: String! house: House! } type House { name: String! words: String! members: [Character]! } Return Types

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Queries for fetching data from the server

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query CharactersNameAndHouse { allCharacters { name house { words } } }

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query CharactersNameAndHouse { allCharacters { name house { words } } } Operation Type

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query CharactersNameAndHouse { allCharacters { name house { words } } } Operation Name

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query CharactersNameAndHouse { allCharacters { name house { words } } } Selection Set

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query CharactersNameAndHouse { allCharacters { name house { words } } } Fields

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query CharactersNameAndHouse { allCharacters { name house { words } } } { "data": { "allCharacters": [ { "name": "Daenerys Targaryen", "house": { "words": "Fire and Blood" } }, { "name": "Jon Snow", "house": { "words": "Winter Is Coming" } } ] } }

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query { character(name: "Hodor") { name house { words } } } Arguments

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query CharacterByName($name: String!) { character(name: $name) { name } } { "name": "Hodor" } Variables

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query { character(name: "Hodor") { ...CharacterFragment } } fragment CharacterFragment on Character { name house { words } } Fragments

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{ character(name: "Hodor") { ... on Character { name house { words } } } } Inline Fragments

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Mutations for manipulating data and fetch the updated result

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type Mutation { createCharacter(name: String!): Character }

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mutation CharacterMutation { createCharacter(name: "Sansa Stark") { name } } { "data": { "createCharacter": { "name": "Sansa Stark" } } }

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Subscriptions for real-time updates

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type Subscription { newCharacter: Character! }

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subscription NewCharacterSubscription { newCharacter { name } } { "data": { "newCharacter": { "name": "Tyrion Lannister" } } }

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Query Execution

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{ getHouse(id: 5) { name words members { name } } }

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name words members getHouse(id: 5) { name, words, members } [ { name }, { name } ] name name

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QUERY name words members getHouse(id: 5) { name, words, members } [ { name }, { name } ] name name

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QUERY getHouse(id: 5) { name, words, members } HOUSE name words members [ { name }, { name } ] name name

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QUERY getHouse(id: 5) { name, words, members } HOUSE name words members [ { name }, { name } ] CHARACTER name name

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Clients with Super Powers

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Introspection Queries

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{ "data": { "__type": { "name": "Book", "kind": "OBJECT", "fields": [ { "name": "title", "type": { "name": "String" } } ] } } } { __type(name: "Book") { name kind fields { name type { name } } } }

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GraphiQL

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Graphene GraphQL framework for Python

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Created September 24, 2015 Updated September 20, 2017 229 Forks 2,356 Stars 1,219 Commits 87 Open Issues https://github.com/graphql-python/graphene

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"It’s important to understand that it isn’t all or nothing. GraphQL is in our future, but it isn’t our exclusive future."

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Thank you!