Introduction to the dark force of

Created by Facebook in 2012

Open sourced in 2015

GraphQL is a query language for your API

GraphQL is a PATTERN not a technology

Created by FB in 2012

Open sourced in 2015

GraphQL is a query language for your API

GraphQL is a PATTERN not a technology

GraphQL doesn't store data

GraphQL is a replacement for REST

GraphQL is a replacement of REST

Instarwarsgram

JSON injected in the UI

{
  "data": {
    "person": {
      "name": "Darth Vader",
      "birthYear": "41.9BBY",
      "planet": {
        "name": "Tatooine"
      },
      "movies": [
        { "title": "A New Hope" },
        { "title": "The Empire Strikes Back" },
        { "title": "Return of the Jedi" },
        { "title": "Revenge of the Sith" }
      ]
    }
  }
}

Person

{
  "data": {
    "person": {
      "name": "Darth Vader",
      "birthYear": "41.9BBY",
      "planetId": 53,
      "movieIds": [1, 2, 3, 6],
      "saberColor"..
    }
  }
}

GET - /person/42

Then.. Planets & Movies

{
  "data": {
    "person": {
      "name": "Darth Vader",
      "birthYear": "41.9BBY",
      "planetId": 53,
      "movieIds": [1, 2, 3, 6],
      "saberColor"...
    },
  }
}

GET - /person/42
    GET - /planets/53
    GET - /movies/1
    GET - /movies/2
    GET - /movies/3
    GET - /movies/6

{
  "data": {
    "planet": {
      "name": "Tatooine",
      "positionX": "234.323",
      "positionY...
     },
  }
}

{
  "data": {
    "movie": {
      "title": "A New Hope",
     },
  }
}

{
  "data": {
    "movie": {
      "title": "A New Hope",
     },
  }
}

{
  "data": {
    "movie": {
      "title": "A New Hope",
     },
  }
}

{
  "data": {
    "movie": {
      "id": 6
      "title": "A New Hope",
      "date": "19/10/1983",
      "personIds"...
     },
  }
}

Result

GET - /person/42
    GET - /planets/53
    GET - /movies/1
    GET - /movies/2
    GET - /movies/3
    GET - /movies/6

{
  "data": {
    "person": {
      "name": "Darth Vader",
      "birthYear": "41.9BBY",
      "planet": {
        "name": "Tatooine"
      },
      "movies": [
        { "title": "A New Hope" },
        { "title": "The Empire Strikes Back" },
        { "title": "Return of the Jedi" },
        { "title": "Revenge of the Sith" }
      ]
    }
  }
}

other implementation

{
  "data": {
    "person": {
      "name": "Darth Vader",
      "birthYear": "41.9BBY",
      "planet": {
        "name": "Tatooine"
      },
      "movies": [
        { "title": "A New Hope" },
        { "title": "The Empire Strikes Back" },
        { "title": "Return of the Jedi" },
        { "title": "Revenge of the Sith" }
      ]
    }
  }
}

GET - /person/42
GET - /person/42/planets
GET - /person/42/movies

Over-fetching

{
  "data": {
    "person": {
      "firstName": "Anakin",
      "lastName": "Skywalker",
      "name": "Darth Vader",
      "birthYear": "41.9BBY",
      "favoriteColor": "black",
      "power": 3000,
      "saberColor": "red",
      "status": "single"
    }
  }
}

REST API always return a fixed structure.

Most of the time you don't need all the information.

Think mobile, and bad network

Under-fetching

GET - /person/42
GET - /person/42/planets
GET - /person/42/movies

We need multiple calls for one view.

Introducing BFF

Backend for Frontend

Back for iOs

Back for Web

Movie

Planet

Person

Monolith

Movie

Planet

Person

Router

BFF method

{
  "data": {
    "person": {
      "name": "Darth Vader",
      "birthYear": "41.9BBY",
      "planet": {
        "name": "Tatooine"
      },
      "movies": [
        { "title": "A New Hope" },
        { "title": "The Empire Strikes Back" },
        { "title": "Return of the Jedi" },
        { "title": "Revenge of the Sith" }
      ]
    }
  }
}

GET - /person/presentation/42

So isn't that good?

Too many endpoints

New features = new endpoints

Hard to maintain

One update = multiple changes

Complex language

Put VS Post VS Patch ?

Query / Params / Body / Headers ?

Poor documentation

Poor validation

Input & Output

Versionning

Now introducing GraphQL

GraphQL is a query language for your API

GraphQL provides

a description of the data in your API

GraphQL is WYWIWYG

* What you want is what you get

query {

}

query {
   person(id: 42)
}

query {
   person(id: 42) {
     name
     birthYear
   }
}

query {
   person(id: 42) {
     name
     birthYear
     planet {
       name
     }
     movies {
       title
     }
   }
}

query {
   person(id: 42) {
     name
     birthYear
     planet {
       name
     }
     movies {
       title
     }
   }
}

{
  "person": {
    "name": "Darth Vader",
    "birthYear": "41.9BBY",
    "planet": {
      "name": "Tatooine"
    },
    "movies": [
      { "title": "A New Hope" },
      { "title": "The Empire Strikes Back" },
      { "title": "Return of the Jedi" },
      { "title": "Revenge of the Sith" }
    ]
  }
}

query {
   person(id: 42) {
     name
     birthYear
     saberColor
     planet {
       name
     }
     movies {
       title
     }
   }
}

{
  "person": {
    "name": "Darth Vader",
    "birthYear": "41.9BBY",
    "saberColor": "red",
    "planet": {
      "name": "Tatooine"
    },
    "movies": [
      { "title": "A New Hope" },
      { "title": "The Empire Strikes Back" },
      { "title": "Return of the Jedi" },
      { "title": "Revenge of the Sith" }
    ]
  }
}

{
  mutation {
     createPlanet(name: "Padoïne") {
       id 
       name
       date
     }
  }
}

{
  mutation {
     createPlanet(name: "Padoïne") {
       id 
       name
       date
       habitant {
         name
       }
     }
  }
}

How does this magic work??

Step 1 - schema.graphql / types definitions

type Person {
  id: ID!
  name: String!
  birthYear: Int!
  picture: String
}

type Person {
  id: ID!
  name: String!
  birthYear: Int!
  picture: String!
  planet: Planet!
  movies: [Movies]
}

type Planet {
  id: ID!
  name: String!
  positionX: Int!
  positionY: Int!
}

scalar DateTime

type Movie {
  id: ID!
  title: String!
  date: DateTime
  actors: [Person]
}

type Person {
  id: ID!
  name: String!
  birthYear: Int!
  picture: String!
  planet: Planet!
  movies: [Movies]
  saberColor: SaberColor
}

enum SaberColor {
  Red
  Blue
  Green
  Purple
  Pink
}

type Planet {
  id: ID!
  name: String!
  positionX: Int!
  positionY: Int!
}

type AirWings implements Vehicule {
  maxSpeed: Int
  droid: Droid
  pilote: Person
}

interface Vehicle {
  maxSpeed: Int
}

scalar DateTime

type Movie {
  id: ID!
  title: String!
  date: DateTime
  actors: Person[]
}

type FalconMilenium implements Vehicule {
    maxSpeed: Int
    pilote1: Person
    pilote2: Person
}

type Query {
  person(id: ID!): Person
  planets: [Planets]
  movies(size: Int, orderBy: String): [Movies]
}

type Query {
  person(id: ID!): Person
  planets: [Planets]
  movies(size: Int, orderBy: String): [Movies]
}

input PersonInput {
  name: String
}

type Mutation {
  createPlanet(name: Planet!): Planet!
  createPerson(person: PersonInput!): Person!
}

type Person {
  id: ID!
  birthYear: Int!
  name: String!
  planet: Planet!
  movies: [Movies]
}

type Planet {
  id: ID!
  name: String!
  positionX: Int!
  positionY: Int!
}

type Movie {
  id: ID!
  title: String!
  date: DateTime
  actors: [Person]
}

type Query {
  person(id: ID!): Person
  planets: [Planets]
  movies(size: Int, orderBy: String): [Movies]
}

typeDefs

2. Resolvers

type Person {
  id: ID!
  birthYear: Int!
  name: String!
  planet: Planet!
  movies: [Movies]
}

type Planet {
  id: ID!
  name: String!
  positionX: Int!
  positionY: Int!
}

type Movie {
  id: ID!
  title: String!
  date: DateTime
  actors: [Person]
}

type Query {
  person(id: ID!): Person
  planets: [Planets]
  movies(size: Int, orderBy: String): [Movies]
}

resolvers

const resolver = (parent, args, ctx, infos) =>

const resolvers = {
  Query: {
    person: (parent, {id}, ctx, infos) => ctx.db.person.findById(id),
    planets: (parent, args, ctx, infos) => ctx.db.planets.findMany(),
    movies: (parent, {size, orderBy}, ctx, infos) => ctx.db.movies.findMany({size,orderBy}),
  },
  Person: {    
    planet: ({planet_id}, {id}, ctx, infos) => ctx.db.planet.findById(planet_id),
    movies: ({movie_ids}, {id}, ctx, infos) => ctx.db.movie.findByIds(movie_ids),
  },
  /*
  Planet: { ..},
  Movie: {.. },
  */
};

resolvers

const resolver = (parent, args, ctx, infos) =>

const resolvers = {
  Query: {
    person: (parent, { id }, ctx, infos) => ctx.db.person.findById(id),
    planets: (parent, args, ctx, infos) => ctx.db.planets.findMany(),
    movies: (parent, { size, orderBy}, ctx, infos) => {
      return ctx.db.movies.findMany({ size, orderBy })
    },
  },
  Person: {    
    id: (parent) => parent.id, // Default Resolver
    name: (parent) => parent.name, // Default Resolver
    birthYear: (parent) => root.birthYear, // Default Resolver
    planet: ({ planet_id }, { id }, ctx, infos) => ctx.db.planet.findById(planet_id),
    movies: ({ movie_ids }, { id }, ctx, infos) => ctx.db.movie.findByIds(movie_ids),
  },
  /*
  Planet: { ..},
  Movie: {.. },
  */
};

resolvers

const resolvers = {
  Query: {
    person: (parent, { id }, ctx, infos) => ctx.db.person.findById(id),
    planets: (parent, args, ctx, infos) => ctx.db.planets.findMany(),
    movies: (parent, { size, orderBy}, ctx, infos) => {
      return ctx.db.movies.findMany({ size, orderBy })
    },
  },
  Person: {    
    id: (parent) => parent.id,
    name: (parent) => parent.name,
    birthYear: (parent) => parent.birthYear,
    planet: ({ planet_id }, { id }, ctx, infos) => ctx.db.planet.findById(planet_id),
    movies: ({ movie_ids }, { id }, ctx, infos) => ctx.db.movie.findByIds(movie_ids),
  },
  /*
  Planet: { ..},
  Movie: {.. },
  */
};

resolvers

query {
   person(id: 42) {
     name
     birthYear
     planet {
       name
     }
     movies {
       title
     }
   }
}

const resolvers = {
  Query: {
    person: (parent, { id }, ctx, infos) => ctx.db.person.findById(id),
    planets: (parent, args, ctx, infos) => ctx.db.planets.findMany(),
    movies: (parent, { size, orderBy}, ctx, infos) => ctx.db.movies.findMany({ size, orderBy }),
  },
  Person: {    
    id: (parent) => parent.id,
    name: (parent) => parent.name,
    birthYear: (parent) => parent.birthYear,
    planet: ({ planet_id }, { id }, ctx, infos) => ctx.db.planet.findById(planet_id),
    movies: ({ movie_ids }, { id }, ctx, infos) => ctx.db.movie.findByIds(movie_ids),
  },
  /*
  Planet: { ..},
  Movie: {.. },
  */
};

Query

query {
   person(id: 42) {
     name
     birthYear
     planet {
       name
     }
     movies {
       title
     }
   }
}

const resolvers = {
  Query: {
    person: (parent, { id }, ctx, infos) => ctx.db.person.findById(id),
    planets: (root, args, ctx, infos) => ctx.db.planets.findMany(),
    movies: (root, { size, orderBy}, ctx, infos) => ctx.db.movies.findMany({ size, orderBy }),
  },
  Person: {    
    id: (parent) => parent.id,
    name: (parent) => parent.name,
    birthYear: (parent) => root.birthYear,
    planet: ({ planet_id }, { id }, ctx, infos) => ctx.db.planet.findById(planet_id),
    movies: ({ movie_ids }, { id }, ctx, infos) => ctx.db.movie.findByIds(movie_ids),
  },
  /*
  Planet: { ..},
  Movie: {.. },
  */
};

Query

query {
   person(id: 42) {
     name
     birthYear
     planet {
       name
     }
     movies {
       title
     }
   }
}

{
  "person": {
  
  }
}

Result

const resolvers = {
  Query: {
    person: (parent, { id }, ctx, infos) => ctx.db.person.findById(id),
    planets: (parent, args, ctx, infos) => ctx.db.planets.findMany(),
    movies: (parent, { size, orderBy}, ctx, infos) => ctx.db.movies.findMany({ size, orderBy }),
  },
  Person: {    
    id: (parent) => parent.id,
    name: (parent) => parent.name,
    birthYear: (parent) => root.birthYear,
    planet: ({ planet_id }, { id }, ctx, infos) => ctx.db.planet.findById(planet_id),
    movies: ({ movie_ids }, { id }, ctx, infos) => ctx.db.movie.findByIds(movie_ids),
  },
  /*
  Planet: { ..},
  Movie: {.. },
  */
};

Query

query {
   person(id: 42) {
     name
     birthYear
     planet {
       name
     }
     movies {
       title
     }
   }
}

{
  "person": {
     "name": "Darth Vader",
     "birthYear": "41.9BBY",
     "planet": { // planet_id = 34
      },
      "movies": [ // movie_ids = [2,4,5,6]
      ]
    }
  }
}

Result

const resolvers = {
  Query: {
    person: (parent, { id }, ctx, infos) => ctx.db.person.findById(id),
    planets: (parent, args, ctx, infos) => ctx.db.planets.findMany(),
    movies: (parent, { size, orderBy}, ctx, infos) => ctx.db.movies.findMany({ size, orderBy }),
  },
  Person: {    
    id: (parent) => parent.id,
    name: (parent) => parent.name,
    birthYear: (parent) => parent.birthYear,
    planet: ({ planet_id }, { id }, ctx, infos) => ctx.db.planet.findById(planet_id),
    movies: ({ movie_ids }, { id }, ctx, infos) => ctx.db.movie.findByIds(movie_ids),
  },
  Planet: {
    name: (root) => root.name
  },
  Movie: {
    title: (root) => root.title
  },
};

Query

query {
   person(id: 42) {
     name
     birthYear
     planet {
       name
     }
     movies {
       title
     }
   }
}

{
  "person": {
     "name": "Darth Vader",
     "birthYear": "41.9BBY",
     "planet": {
        "name": "Tatooine"
      },
      "movies": [
        { "title": "A New Hope" },
        { "title": "The Empire Strikes Back" },
        { "title": "Return of the Jedi" },
        { "title": "Revenge of the Sith" }
      ]
    }
  }
}

Result

Resolvers = Single Source of Truth

3- Server creation

const express = require('express');
const { ApolloServer, gql } = require('apollo-server-express');

const typeDefs = gql`
  type Query {
    hello: String
  }
`;

const resolvers = {
  Query: {
    hello: () => 'Hello world!',
  },
};

const server = new ApolloServer({ typeDefs, resolvers });

const app = express();
server.applyMiddleware({ app });

app.listen({ port: 4000 }, () =>
  console.log('Now browse to http://localhost:4000' + server.graphqlPath)
);

4- Bonus

Directives

directive @deprecated(
  reason: String = "No longer supported"
) on FIELD_DEFINITION | ENUM_VALUE

type ExampleType {
  firstName: String
  first_name: String @deprecated(reason: "Use `newField`.")
}

Directives

directive @rest(url: String) on FIELD_DEFINITION

type Query {
  people: [Person] @rest(url: "/api/v1/people")
}

Directives

directive @auth(
  requires: Role = ADMIN,
) on OBJECT | FIELD_DEFINITION

enum Role {
  ADMIN
  REVIEWER
  USER
  UNKNOWN
}

type User @auth(requires: USER) {
  name: String
  banned: Boolean @auth(requires: ADMIN)
  canPost: Boolean @auth(requires: REVIEWER)
}

Directives

directive @cache(
  time: Duration,
) on FIELD_DEFINITION

enum Duration {
  TenSeconds
  OneMinute
  OneHour
  OneDay
  Forever
}

type Person {
  name: String!
  planet: String! @cache(duration: Forever)
  movies: [Movie] @cache(duration: OneDay)
}

type Query {
  person(id: Person): Person
  movies: [Movie] @cache(duration: OneDay)
}

Subscriptions

type User {
  person: String
}

type Chat {
  id: ID!
  message: [Message]
}

type Query {
  messages(chatId: ID!): [Message]
}

type Mutation {
  createMessage(chatId: ID!, message: String!): Message
}

type Subscription {
  newMessage(chatId: ID!): Message
}

Dataloader

Han Solo

Chewbaca

Episode 4

Episode 5

Episode 6

Episode 4

Episode 5

Episode 6

Episode 3

Dataloader

Han Solo

Chewbaca

Episode 4

Episode 5

Episode 6

Episode 4

Episode 5

Episode 6

Episode 3

api/falconMilenium
api/person/12
api/person/13
api/movie/4
api/movie/5
api/movie/6
api/movie/3
api/movie/4
api/movie/5
api/movie/6

Dataloader

Han Solo

Chewbaca

Episode 4

Episode 5

Episode 6

Episode 4

Episode 5

Episode 6

Episode 3

api/falconMilenium
api/person/12
api/person/13
api/movie/4
api/movie/5
api/movie/6
api/movie/3
api/movie/4
api/movie/5
api/movie/6

Dataloader

Han Solo

Chewbaca

Episode 4

Episode 5

Episode 6

Episode 4

Episode 5

Episode 6

Episode 3

api/falconMilenium
api/persons?id=12,13
api/movie?3,4,5,6

A lot of possibilities ..

type PersonMutation {
  name(name: String): String
  hairColor(color: Color): Color
  danse(danse: Danse): Danse
  fight(name: String!): Fight
}

type Mutation {
   person(name: String!): PersonMutation
}

mutation {
   person(name: "Anakin Skywalker") {
     name(name: "Darth Vader")
     hairColor(color: Black)
     fight(name: "Obiwan Kenobi") {
       person {
         id
         lifePoint
       }
     }
  }
}

Scalability with Apollo Federation

Typings from server to client

git clone git@github.com:LucM/apollo-wars.git
cd apollo-wars
npm i 
npm run dev

Give it a try!

https://apollo-wars.herokuapp.com/

JSON injected in the UI

Person

Then.. Planets & Movies

Result

other implementation

Over-fetching

Under-fetching

Introducing BFF

Backend for Frontend

Monolith

BFF method

Too many endpoints

Hard to maintain

Complex language

Poor documentation

Poor validation

Versionning

Now introducing GraphQL

Directives

Directives

Directives

Directives

Subscriptions

Dataloader

Dataloader

Dataloader

Dataloader

A lot of possibilities ..

Scalability with Apollo Federation

Typings from server to client

Introduction to GraphQL

Introduction to GraphQL

Luc Momal

JSON injected in the UI

Person

Then.. Planets & Movies

Result

other implementation

Over-fetching

Under-fetching

Introducing BFF

Backend for Frontend

Monolith

BFF method

Too many endpoints

Hard to maintain

Complex language

Poor documentation

Poor validation

Versionning

Now introducing GraphQL

Directives

Directives

Directives

Directives

Subscriptions

Dataloader

Dataloader

Dataloader

Dataloader

A lot of possibilities ..

Scalability with Apollo Federation

Typings from server to client

Introduction to GraphQL

More from Luc Momal