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Introduction to GraphQL
Adrián Matellanes
September 23, 2017
Programming
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400
Introduction to GraphQL
Learn about GraphQL, how it works, and how to use it.
Adrián Matellanes
September 23, 2017
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Transcript
Introduction to GraphQL
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" }
What’s GraphQL?
A programming language
A special type of database
A library
A Query Language for APIs
Why GraphQL?
Due to the nature of REST
REST Problems
GET /characters/1 { "name": "Jon Snow" }
"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"
Round Trip and Repeat Trip Times
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/episodes/1
/episodes/1 /characters/345 /characters/563 /characters/802 /characters/441 /characters/674
/episodes/1 /characters/345 /characters/563 /characters/802 /characters/441 /characters/674 /reviews/3512
Over/Under Fetching
/episodes/1?fields=characters(name,playedBy)
/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
/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/
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
REST Model
Client /books /characters /houses Databases Services External APIs
GraphQL Model
Client Databases Services External APIs /graphql/
Anatomy of a GraphQL
{ me { name } }
{ me { name } } { "me": { "name":
"Jon Snow" } }
Scalar types
Int Float String Boolean ID Date enum
GraphQL Schema Definition Language
type Query { allCharacters: [Character]! character(id: ID!): Character }
type Query { allCharacters: [Character]! character(id: ID!): Character } Root
Type
type Query { allCharacters: [Character]! character(id: ID!): Character } Root
Fields
type Query { allCharacters: [Character]! character(id: ID!): Character } Arguments
type Query { allCharacters: [Character]! character(id: ID!): Character } Return
Types
type Character { name: String! house: House! } type House
{ name: String! words: String! members: [Character]! }
type Character { name: String! house: House! } type House
{ name: String! words: String! members: [Character]! } Object Type
type Character { name: String! house: House! } type House
{ name: String! words: String! members: [Character]! } Fields
type Character { name: String! house: House! } type House
{ name: String! words: String! members: [Character]! } Return Types
Queries for fetching data from the server
query CharactersNameAndHouse { allCharacters { name house { words }
} }
query CharactersNameAndHouse { allCharacters { name house { words }
} } Operation Type
query CharactersNameAndHouse { allCharacters { name house { words }
} } Operation Name
query CharactersNameAndHouse { allCharacters { name house { words }
} } Selection Set
query CharactersNameAndHouse { allCharacters { name house { words }
} } Fields
query CharactersNameAndHouse { allCharacters { name house { words }
} } { "data": { "allCharacters": [ { "name": "Daenerys Targaryen", "house": { "words": "Fire and Blood" } }, { "name": "Jon Snow", "house": { "words": "Winter Is Coming" } } ] } }
query { character(name: "Hodor") { name house { words }
} } Arguments
query CharacterByName($name: String!) { character(name: $name) { name } }
{ "name": "Hodor" } Variables
query { character(name: "Hodor") { ...CharacterFragment } } fragment CharacterFragment
on Character { name house { words } } Fragments
{ character(name: "Hodor") { ... on Character { name house
{ words } } } } Inline Fragments
Mutations for manipulating data and fetch the updated result
type Mutation { createCharacter(name: String!): Character }
mutation CharacterMutation { createCharacter(name: "Sansa Stark") { name } }
{ "data": { "createCharacter": { "name": "Sansa Stark" } } }
Subscriptions for real-time updates
type Subscription { newCharacter: Character! }
subscription NewCharacterSubscription { newCharacter { name } } { "data":
{ "newCharacter": { "name": "Tyrion Lannister" } } }
Query Execution
{ getHouse(id: 5) { name words members { name }
} }
name words members getHouse(id: 5) { name, words, members }
[ { name }, { name } ] name name
QUERY name words members getHouse(id: 5) { name, words, members
} [ { name }, { name } ] name name
QUERY getHouse(id: 5) { name, words, members } HOUSE name
words members [ { name }, { name } ] name name
QUERY getHouse(id: 5) { name, words, members } HOUSE name
words members [ { name }, { name } ] CHARACTER name name
Clients with Super Powers
Introspection Queries
{ "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
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."
Thank you!