GraphQL is a declarative data fetching method that provides a single endpoint for queries. It was developed by Facebook in 2012 and addresses challenges with REST like over- and under-fetching of data. GraphQL uses a schema to define types and their relations, and allows fetching nested data in a single query to the server. It supports queries to read data, and mutations to write data by creating, updating, or deleting data records.

1. GETTING STARTED
WITH GraphQL
Agilize Cloud Accounting, 24/11/2017
Weekly company-internal DevTalks

3. 1.
DEFINE: GraphQL

4. WHAT IS GRAPHQL
○ Declarative data fetching
○ Alternative to REST
○ Single endpoint → responds to queries

5. /authors/<id>
/authors/<id>/books
/authors/<id>/followers
3 ENDPOINTS

6. query
query
query
1 SINGLE
ENDPOINT

7. DEMO 1

8. 2.
CHARACTERISTICS

9. GraphQL TIMELINE
○ Developed by Facebook on 2012
○ Presented → React.js Conf 2015
○ Is not for React Developers
○ Other companies had the same initiative
○ Netflix → Falcor
○ Cousera → Now uses GraphQL

10. REST CHALLENGES
○ Need for efficient data loading (mobile)
○ Variety of different frontend frameworks
○ Rapid feature development

11. GraphQL BENEFITS
○ No mover over or underfetching
○ Almost non API if the interface changes
○ Faster feedbacks cycles

12. INSIGHTFUL ANALYTICS
○ Fine-grained info about what read data
○ Evolving and deprecating API

13. 3.
KEY CONCEPTS

14. type Query {
...
}
type Mutation {
...
}
type Subscription {
...
}
ROOT TYPE

15. query {
User(id: 123) {
name
posts {
title
}
}
}
QUERY
HTTP POST

16. {
"data": {
"User": {
"name": "Joston Muriel",
"posts": [
{title: "Hello, it's me"}
{title: "Lines in the sand"}
]
}
}
}
RESPONSE
RESPONSE

17. SCHEMA
○ Strong type system
○ Schema as client-server contract
○ Client and server can work independently
○ Schema Definition Language

18. type Person {
name: String!
age: Int!
}
DEFINING SIMPLE TYPES
! → required

19. type Person {
name: String!
age: Int!
}
ADDING A RELATION
type Post {
title: String!
author: Person!
}

20. type Person {
name: String!
age: Int!
posts: [Post!]!
}
ADDING A HAS-MANY RELATION
type Post {
title: String!
author: Person!
}

21. DEMO 2

22. 4.
MUTATIONS

23. WRITING DATA WITH MUTATIONS
○ A query too
○ You can ask for the returning fields
○ Even nested ones

24. 3 KINDS OF MUTATIONS
○ creating new data
○ updating existing data
○ deleting existing data

25. A MUTATION
mutation {
createPerson(name: "Bob", age: 36) {
name
age
}
}
Similar syntax. Mutation keyword. Special root field.

26. DEFINING A MUTATION
type Mutation {
createPerson(name: String!, age: String!) Person!
...
}

27. 5.
NODE EXAMPLE

28. DEMO 3

29. “
Nescit cedere

30. Any questions?