GRAPHQLINDYJS MEETUP APRIL 2016

MEMES…

REST

REST IS AN ACRONYM FOR ?

REST

REST HISTORY

▸ The term representational state transfer was introduced and defined in 2000 by Roy Fielding

▸ The defacto standard for communicating with a server

▸ Defines simple operations: GET, PUT, POST, DELETE

▸ A query operation (like GET) promises no side-effects (e.g. changes) in data being queried. Commands (like PUT/DELETE) answer no questions about the data, but compute changes applied to the data (e.g. UPDATE or INSERT to use database terms).

REST

REST ISSUES

▸ Many endpoints - proliferation of ad hoc endpoints

▸ Many round trips between the client and server

▸ First fetch pilots, then fetch homeworld info for each pilot, then…

▸ Very expensive for mobile apps

▸ Response structure may change over time

▸ Data overfetching

▸ We don’t always need all the data for a REST call

▸ Usually no metadata

▸ Big blob of data…we can’t run inquires on it’s types or structure

REST

FIXES FOR REST??

▸ Define your own ad-hoc query language

▸ Use REST PATCH to minimize data transfer ?

▸ REST API introspection via Swagger (http://swagger.io/)

GRAPHQL

JAVASCRIPT FATIGUE

BECAUSE A NEW JAVASCRIPT FRAMEWORK IS RELEASED

GRAPHQL

WHAT IS GRAPHQL?

▸ Queries describe the shape of data that the client needs. The response has the same structure as the request query.

▸ Server interprets GraphQL calls and queries the database (or any other source of data)

▸ GraphQL is language-, database- and protocol-agnostic

GRAPHQL WAS INVENTED AT FACEBOOK IN 2012, BUT IT WAS FIRST SHOWN TO PUBLIC IN 2015 DURING REACT.JS CONF AS A PART OF FACEBOOK OPEN-SOURCE ECOSYSTEM.

GRAPHQL

GRAPHQL MOTIVATION

▸ Single endpoint

▸ Hierarchical nature

▸ Strongly typed - enables validation, introspection and more

▸ Response mirrors the shape of the query

▸ Introspection - make inquiries from your client about the schema

▸ Application-Layer Protocol

▸ GraphQL is an application-layer protocol and does not require a particular transport. It is a string that is parsed and interpreted by a server.

GRAPHQL

GRAPHS - DAG/AST

*

-

397

+

6

DIRECTED ACYCLIC GRAPH ABSTRACT SYNTAX TREES

(6 + 7) * (9 - 3)

GRAPHQL

GRAPHS PERSON [NAME, ID, …]

STARSHIP-A [ID, MANUF,..]

STARSHIP-B [ID, MANUF,..]

STARSHIP-C [ID, MANUF,..]

PILOT-A [ID, NAME,..]

STARSHIP CONNECTION

STARSH

IP CONNECT

ION

STARSHIP CONNECTION

PILOT CONNECTION

HOMEWORLD-A [ID, NAME,..]

HOMEWORLD CONNECTION

HOMEWORLD CONNECTION

NODE

NODE

EDGE

GRAPHQL

FOLLOW ALONG!

▸ Go here and follow along with me

▸ http://graphql-swapi.parseapp.com

GRAPHQL

BASIC QUERY

GRAPHQL

NESTED FIELDS

GRAPHQL

CONNECTIONS

GRAPHQL

MANY CONNECTIONS

GRAPHQL

ARGUMENTS

GRAPHQL

FRAGMENTS

GRAPHQL

MORE FRAGMENTS

GRAPHQL

INTROSPECTION

GRAPHQL

SCARED YET?

▸ Syntax (covered)

▸ Type System

▸ Resolving

▸ Edges/Nodes & Pagination

GRAPHQL

GRAPHQL TYPE SYSTEM

▸ Scalars - basic types

▸ Schema - a representation of the capabilities of the GraphQL server

▸ Definitions - defining types

▸ Predicates - meta info on types

▸ Un-modifiers - type “un” modifiers

GRAPHQL

GRAPHQL SCALARS

▸ GraphQLInt - integer number

▸ GraphQLFloat - float number

▸ GraphQLString - string

▸ GraphQLBoolean - boolean

▸ GraphQLID - represents an ID (essentially a string)

GRAPHQL

GRAPHQL SCHEMAS

▸ It all starts with a “root” query

▸ Fields on type can be plain data or “resolved”

▸ You can define your own types

▸ You can define/override the serialization on a type

▸ You can add enhanced validation to types

▸ From a schema, you can generate a more human readable schema and JSON based schema for clients to use

GRAPHQL

GRAPHQL DEFINITIONS

▸ GraphQLScalarType - the class of scalars

▸ GraphQLObjectType - an object

▸ GraphQLInterfaceType - a interface

▸ GraphQLUnionType - a union

▸ GraphQLEnumType - enum

▸ GraphQLInputObjectType

▸ GraphQLList - what you use for lists arrays of objects

▸ GraphQLNonNull - an object for which null is an invalid value

GRAPHQL

GRAPHQL DATA RESOLUTION▸ Resolve to data - synchronous

result. Return the data as teh result of a resolve.

▸ Resolve to promise - asynchronous result. Return a promise that will return the data in the future. My preference is to use ES6 and async functions (which actually return promises).

GRAPHQL

GRAPHQL EDGES/NODES

▸ Not built into the language, but provided by types

▸ The type Facebook uses and I recommend you use too, are in : https://github.com/graphql/graphql-relay-js

▸ Using edges and nodes allow for pagination. If you don’t need pagination, then use a simple GraphQLList.

GRAPHQL

RUNNING ON EXPRESS https://github.com/graphql/graphql-js

GRAPHQL

EXAMPLE SCHEMA

GRAPHQL

CUSTOM SCALAR

Credits: Snippet from https://github.com/mattkrick/meatier

GRAPHQL

BUILD IT!

▸ Build your server…I use Babel and ES6

▸ You’ll also need to run (see sample code) a script to “update” your schema. This creates a client and a human readable version of your schema.

▸ If you are using Relay, you will also need to use the Babel-Relay plugin to consume, compile and validate your GraphQL queries in your components.

▸ You also need to tell the Babel-Relay plugin where to find the schema you built above (the JSON form).

GRAPHQL

MAKE SENSE?

▸ Hopefully more sense than Chewy!

GRAPHQL

GRAPHQL MISUNDERSTANDINGS

▸ All of the queries you see are defined by your schema. I.e. things like viewer, user, edge, node are defined by the schema and not an inherent part of the language.

▸ GraphQL is Javascript only. Nope!

▸ There are 3rd party ports for Python, Scala, Go, Ruby, etc.

▸ GraphQL requires special communications protocol. Nope!

▸ The default implementation uses a basic REST post call, but you can use web sockets, etc. and even mix and match.

GRAPHQL & RELAY

RESOURCES

▸ Cartoon Guides To GraphQL: https://code-cartoons.com

▸ Awesome GraphQL - curated list on Github: https://github.com/chentsulin/awesome-graphql

GRAPHQL & RELAY

MORE RESOURCES

▸ GraphQL Home: http://graphql.org/

▸ GraphQL Spec: https://facebook.github.io/graphql/

▸ Many REST APIs you can experiment with using GraphQL: https://www.graphqlhub.com/

QUESTIONS??? ▸ Twitter: @BradPillow, GitHub: pillowsoft

THANKS!