Intro to
GraphQL
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Sabin Marcu
Software Engineer at R/GA
Been working in web since '09
React Dev since 2015
React trainer @ JSLeague
Whoami
Overview
Intro to GraphQL
Intro to GraphQL
Agenda
Async Resolve Functions
Nested Queries
Usage with Prisma
RootQuery Entry Points
Bidirectional Relations
Circular References
Introduction
Language and Entities
REST-ful Routing
GraphQL Schemas
Root Queries
The GraphiQL Tool
Introduction
Intro to GraphQL
Intro to GraphQL
What is it?
a syntax that describes how to ask for data
Intro to GraphQL
It lets the client specify exactly what data it needs
It makes it easier to aggregate data from multiple sources
It uses a type system to describe data
Why?
Intro to GraphQL
Language and Entities
Intro to GraphQL
Intro to GraphQL
Type System
{
hero {
name
appearsIn
}
}{
"data": {
"hero": {
"name": "R2-D2",
"appearsIn": [
"NEWHOPE",
"EMPIRE",
"JEDI"
]
}
}
}Object types and fields
Intro to GraphQL
type Character {
name: String!
appearsIn: [Episode!]!
}
object type
fields
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type Character {
name: String!
appearsIn: [Episode!]!
}String = scalar type, can't have sub-selections in the query
String! = non-nullable
[Episode!]! = non-nullable array of Episode objects
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Arguments
type Starship {
id: ID!
name: String!
length(unit: LengthUnit = METER): Float
}
argument
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3 root operations
type Query {
... query operations ...
}
type Mutation {
... mutation operations ...
}
type Subscription {
... subscription operations ...
}Intro to GraphQL
type Query {
hero(episode: Episode): Character
droid(id: ID!): Droid
}query {
hero {
name
}
droid(id: "2000") {
name
}
}{
"data": {
"hero": {
"name": "R2-D2"
},
"droid": {
"name": "C-3PO"
}
}
}Intro to GraphQL
Scalar types
- Int, Float, String, Boolean, ID
- custom: Date
- special: Enums
Entity types
type Character {
name: String!
appearsIn: [Episode!]!
}Intro to GraphQL
Interfaces
interface Character {
id: ID!
name: String!
friends: [Character]
appearsIn: [Episode]!
}type Human implements Character {
id: ID!
name: String!
friends: [Character]
appearsIn: [Episode]!
starships: [Starship]
totalCredits: Int
}
type Droid implements Character {
id: ID!
name: String!
friends: [Character]
appearsIn: [Episode]!
primaryFunction: String
}Intro to GraphQL
Union types
union SearchResult = Human | Droid | Starship{
search(text: "an") {
__typename
... on Human {
name
height
}
... on Droid {
name
primaryFunction
}
... on Starship {
name
length
}
}
}{
"data": {
"search": [
{
"__typename": "Human",
"name": "Han Solo",
"height": 1.8
},
{
"__typename": "Human",
"name": "Leia Organa",
"height": 1.5
},
{
"__typename": "Starship",
"name": "TIE Advanced x1",
"length": 9.2
}
]
}
}Intro to GraphQL
Input types
input ReviewInput {
stars: Int!
commentary: String
}mutation CreateReviewForEpisode($ep: Episode!, $review: ReviewInput!) {
createReview(episode: $ep, review: $review) {
stars
commentary
}
}{
"data": {
"createReview": {
"stars": 5,
"commentary": "This is a great movie!"
}
}
}Q&A
JavaScript Beyond the Basics
Thank you!
Intro to GraphQL
By Alex Albu
