GraphQL – the future of APIs?
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GraphQL is a strongly-typed query language and runtime that enables flexible data representation and retrieval. It allows for defining schemas for data, queries, and mutations, and includes features like object types, interfaces, and input types. GraphQL differs from REST in being a comprehensive specification and tools rather than just an architectural concept, and has been adopted by major companies like Facebook and GitHub.
![I have a data. What’s next?
5
1. Define a schema for data representation
GraphQL Schema:
type Campaign {
name: ID!
title: String
running: Boolean
ads: [Ad]
}
Elixir DSL:
object :campaign do
field :id, non_null(:id)
field :title, :string
field :running, :boolean
field :ads, list_of(:ad),
resolve: assoc(:ads)
end](https://image.slidesharecdn.com/graphql-thefutureofapis-171008085902/85/GraphQL-the-future-of-APIs-5-320.jpg)
![I have a data. What’s next?
8
4. Make some queries
GraphQL query:
query {
campaign(id: 1) {
running
ads {
budget {
amount
}
}
}
}
GraphQL mutation:
mutation {
createCampaign(
title: "New campaign",
running: false, ads: [
{title: “LI 1"}
]) {
id
}
}](https://image.slidesharecdn.com/graphql-thefutureofapis-171008085902/85/GraphQL-the-future-of-APIs-8-320.jpg)
![Lists & Enumeration Types
• Lists defined with [ and ] around type.
• Enum – special type of scalar with a restricted set of
possible values:
enum Episode {
FIRST
SECOND
THIRD
}
11](https://image.slidesharecdn.com/graphql-thefutureofapis-171008085902/85/GraphQL-the-future-of-APIs-11-320.jpg)
![Object Types
• Object type – named set of fields with theirs types.
• Fields could be scalars or other object types, enums, lists.
• Fields could be marked as non-nullable:
type Ad {
title: String!
targetings: [Targeting!]!
}
12](https://image.slidesharecdn.com/graphql-thefutureofapis-171008085902/85/GraphQL-the-future-of-APIs-12-320.jpg)
GraphQL – the future of APIs?
- 1. GraphQL – the future of APIs? - OR - GraphQL in a brief Dmitry Stropalov, Sizmek Kraków 2017
- 2. What is GraphQL • GraphQL is a (query) language - declarative - hierarchical - strongly typed • GraphQL is a runtime - execution layer - technology agnostic 2
- 3. Yet another technology? • Era of mobile devices • Flexibility & Transparency • Productivity & Costs 3
- 5. I have a data. What’s next? 5 1. Define a schema for data representation GraphQL Schema: type Campaign { name: ID! title: String running: Boolean ads: [Ad] } Elixir DSL: object :campaign do field :id, non_null(:id) field :title, :string field :running, :boolean field :ads, list_of(:ad), resolve: assoc(:ads) end
- 6. I have a data. What’s next? 6 2. Define a schema of queries and mutations GraphQL Schema: type Query { campaign(id: ID!): Campaign } Elixir DSL: field :campaign, :campaign do arg :id, non_null(:id) resolve &CampaignResolver.find/2 end
- 7. I have a data. What’s next? 7 3. Implement resolvers for queries and mutations Elixir: def find(%{id: id}, _info) do case Repo.get(Campaign, id) do nil -> {:error, "Campaign #{id} not found"} campaign -> {:ok, campaign} end end
- 8. I have a data. What’s next? 8 4. Make some queries GraphQL query: query { campaign(id: 1) { running ads { budget { amount } } } } GraphQL mutation: mutation { createCampaign( title: "New campaign", running: false, ads: [ {title: “LI 1"} ]) { id } }
- 9. GraphQL Schema 9 • Scalar Types • Lists & Enumeration Types • Object Types • Interfaces & Unions • Arguments • Input types
- 10. Scalar Types 10 • Int: A signed 32‐bit integer. • Float: A signed double-precision floating-point value. • String: A UTF‐8 character sequence. • Boolean: true or false. • ID: non human-readable String. • Custom scalars via scalar keyword.
- 11. Lists & Enumeration Types • Lists defined with [ and ] around type. • Enum – special type of scalar with a restricted set of possible values: enum Episode { FIRST SECOND THIRD } 11
- 12. Object Types • Object type – named set of fields with theirs types. • Fields could be scalars or other object types, enums, lists. • Fields could be marked as non-nullable: type Ad { title: String! targetings: [Targeting!]! } 12
- 13. Interfaces & Unions • Interface – an abstract object type: interface Player { nickname: String! } type User implements Player { nickname: String! … } • Union – specifies a set of possible object types: union SearchResult = Picture | Video | Document search(text: "Kraków") { … on Picture { size } … on Video { length } … on Document { format } } 13
- 14. Arguments • Every field of an object type can have zero or more arguments: type FuelTank { volume(unit: VolumeUnit = LITRE): Float } • All arguments are named. • Could be required or optional. 14
- 15. Input Types • Input types – object types used for mutations. • Input and output object types can’t be mixed. • No arguments on input object fields. 15
- 16. GraphQL Queries 16 Fields, aliases, fragments and other things
- 17. Introspection & Docs • Introspection is built-in via special __schema object. • Any type introspection via __type object. • Documentation is a part of schema definition: @desc "Get campaign by ID." field :campaign, :campaign do arg :id, non_null(:id), description: "Specifies campaign ID.” resolve &CampaignResolver.find/2 end 17
- 18. API Versioning • GraphQL can’t have “v1”-style versioning. • Evolution is the key. 18
- 19. One more “v1” thing 19
- 20. –Monty Python “And now for something completely different …” 20
- 21. The Glory of REST 21 From the article “Richardson Maturity Model” by M.Fowler
- 22. GraphQL & REST • GraphQL is a language, specification and tools while REST is an architectural concept. • GraphQL is completely independent of a transport protocol used. • With GraphQL you can think in terms of a business logic objects instead of resources. • Different caching approaches. • API payload optimisations. • Field usage monitoring. 22
- 23. Adoption • Facebook • GitHub • Twitter • Airbnb • The New York Times • Wirtualna Polska • Coursera • Dailymotion 23
- 24. The End