From Back to Front:Rails to React Family

Khor Soon Hin, @neth_6

Outline● React Family: ReactJS/Flux/RelayJS/GraphQL● What makes them interesting?● What are they? How they work together?● How do I get started easily?● Should I use them all?● IMPORTANT: How to get them onto Rails

React/Flux/Relay/GraphQL: In A Sentence Each

● React: UI● Flux: Data Flow● GraphQL: Data Retrieval● Relay: Component-Data Co-location

React/Flux/Relay/GraphQL: Common Goal

Improve software quality given the same development time

React/Flux/Relay/GraphQL: Common Goal

Improve software quality given the same development time

● Easy to understand & debug● Less prone to error

React/Flux/Relay/GraphQL: Common Approach

Simplify abstraction to push common tasks/code organization to pattern/framework

React/Flux/Relay/GraphQL: Common Approach

Simplify abstraction to push common tasks/code organization to pattern/framework

● Easy to understand & debug

React/Flux/Relay/GraphQL: Common Approach

Simplify abstraction to push common tasks/code organization to pattern/framework

● Easy to understand & debug● Less prone to error

React/Flux/Relay/GraphQL: Common Outcome

Functional/Declarative Programming

React: UI

React

● Single-Page Application (SPA)

Courtesy: https://facebook.github.io/react/docs/thinking-in-react.html

React (cont.)

● Single-Page Application (SPA)● Cascading Views

React (cont.)

● Single-Page Application (SPA)● Cascading Views

React (cont.)Abstraction

Each React element knows:

● The data it needs● How to render itself with HTML fragments● The data it passes to its children

React (cont.)

● Single-Page Application (SPA)● Cascading Views

Fetch Data

React (cont.)

● Single-Page Application (SPA)● Cascading Views

React (cont.)

● Single-Page Application (SPA)● Cascading Views

React (cont.)

● Single-Page Application (SPA)● Cascading Views

Uni-directional Flow

React (cont.)

● Single-Page Application (SPA)● Cascading Views

Debug Upwards

React (cont.)

jQuery: You need to find all the pieces of code that modified the UI in error

React: User Interaction

ball

React: User Interaction (cont.)

ball

React: Data Change (cont.)

ball

React: User Interaction (cont.)

ball

React: User Interaction (cont.)

jQuery: You need to find element to modify and make modification

Imperative vs. Functional: Coding● Imperative:

○ Example: jQuery code■ Code is likely in a monolithic Javascript■ Hold element ids for where each piece of data should be shown■ Retrieves element and display data■ Complex model requires customized code:

● Find pieces of data, and update pieces of element

● Functional:○ Example: React code

■ Code is contained within each React element:■ Each React element declares which part of data to pass on to children■ Each React element declares how to render data it receives■ Simplified model reduces code relinquish more to framework:

● Provide data to top view, and cascading views redraws themselves

Functional vs. Imperative: Benefits● Imperative:

○ Complex model requires customized code■ Dig through customized code to understand relationships■ Different pieces of code to initialize UI, and update based on interaction

● Functional:○ Simplified model reduces code relinquish more to framework

■ Relationship and data-flow is top-down■ Same piece of code to initialize, and update UI

React On Rails● https://github.com/reactjs/react-rails● app/assets/javascripts/components/xxxxx.js

○ Dump all your React components related to xxxxx

React: Codevar DATA = [ { category: 'Sporting Goods', products: [ {price: '$49.99', stocked: true, name: 'Football'}, {price: '$9.99', stocked: true, name: 'Baseball'}, {price: '$29.99', stocked: false, name: 'Basketball'}, ], }, { category: 'Electronics', products: [ {price: '$99.99', stocked: true, name: 'iPod Touch'}, {price: '$399.99', stocked: false, name: 'iPhone 5'}, {price: '$199.99', stocked: true, name: 'Nexus 7'}, ], },];

React: Code (cont.)// Javascript required in app/assets/javascripts/application.js

ReactDOM.render( <ProductTable data={DATA} />, document.getElementById('container'));

React: Code (cont.)

// app/assets/javascripts/components/product.jsx

var ProductTable = React.createClass( render: function() { var rows = []; this.props.data.forEach(function(dataElem) { rows.push(<ProductCategoryRow category={dataElem.category} … />); dataElem.products.forEach(function(product) { rows.push(<ProductRow product={product} … />); }); ...

var DATA = [ { category: 'Sporting Goods', products: [ {name: 'Football', ...}, {name: ’Baseball’, ... }, ... ], }, { category: 'Electronics', products: [ {name: 'iPod Touch', ...}, {name: ‘iPhone 6’, …}, ... ], },];

React: Code (cont.)

// app/assets/javascripts/components/product.jsx

var ProductCategoryRow = React.createClass({ render: function() { return (<tr><th>{this.props.category}</th></tr>); }});

React: Code (cont.)// app/assets/javascripts/components/product.jsx

var ProductRow = React.createClass({ render: function() {

return ( <tr> <td>{this.props.product.name}</td> <td>{this.props.product.price}</td> </tr> );

}});

React: SummarySimplify abstraction

● UI○ Shove data for entire UI from the top component○ Each component render itself with data for self○ Each component pass data to child○ To change component, just change data

Framework

● Handle initializing/updating UI with the right pieces of data

How

● Re-drawing all UI pieces efficiently

Flux: Data Flow

React

Courtesy: https://facebook.github.io/react/docs/thinking-in-react.html

MVC

Courtesy: http://fluxxor.com/what-is-flux.html

Multiple Models/Domains

Chat

News

Summary

Friend Requests

MVC ComplexityExplosion of flows

Courtesy: http://fluxxor.com/what-is-flux.html

MVC Complexity

Courtesy: http://fluxxor.com/what-is-flux.html

News

SummaryNews

One model powering 2 views

MVC Complexity

Courtesy: http://fluxxor.com/what-is-flux.html

News

SummaryNews

Friends

One model powering 2 views

Two models powering 1 view

MVC ComplexityExplosion of flows

Error in UI

MVC Complexity (cont.)Explosion of flows

Error in UI

MVC Complexity (cont.)Explosion of flows

Error in UI

MVC Complexity (cont.)Explosion of flows

Error in UI

Tracing LoopsDifficult:

● Tons of log entries○ Lots of things to look through○ Scrolling is laggy

● Cannot just look at snapshot for messy loops

MVC Simple Loops

Error in UI

Tracing (if set correctly) may tell you where loop is

MVC Looping the LoopExplosion of flows

Error in UI

Depending on where you look in the trace, you may think orange or bold loop

A loop resulting in another loop

MVC Simultaneous LoopsExplosion of flows

Error in UI

Tracing is difficult; seeing two traces

A loop resulting in multiple other loops concurrently

Flux

Courtesy: http://fluxxor.com/what-is-flux.html

Trigger ActionAction Done

Action DoneState Update

Structured and self-contained

Flux (cont.)

Courtesy: http://fluxxor.com/what-is-flux.html

Take ActionAction Done

Action DoneState Update

● Throttles one Action at a time● waitsFor()

● Synchronous tasks only● State and logic co-located

Flux (cont.)

Courtesy: http://fluxxor.com/what-is-flux.html

register register

With Flux

Courtesy: http://fluxxor.com/what-is-flux.html

Side-by-side

MVC Flux

Side-by-side● Structured growth (no path explosion):

○ Parallel stores lead to single top view

MVC Flux

Side-by-side● Structured growth (no path explosion):

○ Parallel stores lead to single top view○ Single-parent cascading views

MVC Flux

React

Side-by-side● Structured growth (no path explosion):

○ Parallel stores lead to single top view○ Single-parent cascading views

● Controllers-Models collapsed into Stores to co-locate logic & state

MVC Flux

React

Store

Store

With Flux

Error in UI

Only one trace at a time

● Dispatcher throttles Actions

A loop resulting in multiple other loops concurrently

With Flux

Error in UI

register

register

With Flux

Error in UI

register

register

Todo App

New Todo

Create

Todo #1

Todo #2Created Todo List

Action Creator Trigger<form>

<input id=’todo-text’ type=’text’ />

<button onClick=TodoActions.create($(‘#todo-text’).val())>Create</button>

</form>

Action CreatorTodoActions: { create: function(text) { // Take some action, e.g., call REST API AppDispatcher.dispatch({ actionType: TodoConstants.TODO_CREATE, // Basically ‘create’ text: text }); }, ….}

DispatcherAppDispatcher = require('flux').Dispatcher;

StoreAppDispatcher.register(function(action) { // action is passed in by Action Creatorvar event = action.event; switch(action.actionType) { case TodoConstants.TODO_CREATE: // Do whatever, e.g., update local store data or fetch fresh data from server TodoStore.emitChange(); break; …. }}

register

Store (cont.)var TodoStore = assign({}, EventEmitter.prototype, { // EventEmitter provides emit, on, removeListener, etc. methods addChangeListener: function(callback) { this.on(CHANGE_EVENT, callback); }, removeChangeListener: function(callback) { this.removeListener(CHANGE_EVENT, callback); }, emitChange: function() { this.emit(CHANGE_EVENT); }, ...}

register

Controller-View// This is where React is usedvar TodoApp = React.createClass({ componentDidMount: function() { TodoStore.addChangeListener(this._onChange); }, componentWillUnmount: function() { TodoStore.removeChangeListener(this._onChange); }, _onChange: function() { this.setState(TodoStore.getData()); }, ...}

register

Flux: More Pattern than Framework● Many implementations● Flux:

○ By Facebook

● Redux:○ Not pure Flux per se, but embraces its spirit○ Server-side rendering built-in○ Growing super-fast

● Alt:○ Pure Flux compliant○ Well-documented, great community○ Server-side rendering built-in

Flux Documentation Quirks● Uses native dispatcher, not the official Facebook dispatcher

○ Use official Facebook dispatcher

● Does not use Flux-Utils○ Use Flux-Utils to create Stores without code duplication

Rails with pure Flux: https://medium.com/@khor/back-to-front-rails-to-facebook-s-flux-ae815f81b16c

GraphQL: Data Retrieval

GraphQL

I speak GraphQL

API Endpoint

GraphQL (cont.)

API Endpoint

query { store(email: "admin@abc.com") { name, address }}

GraphQL (cont.)

API Endpoint

query { store(email: "admin@abc.com") { name, address }}

store(email: “admin@abc.com”) { name: ‘Hello Shop’, address: ‘1-3-1 Aoyama’}

GraphQL (cont.)

API Endpoint

query { store(email: "admin@abc.com") { categories { name, products { name, price, stock } } }}

store { categories: [ { name: ‘Sporting Goods’, products: [ { name: ‘Football’, price:, stock: 50 }, … }, ... ]}

From React example

GraphQL (cont.)

API Endpoint

query { store(email: "admin@abc.com") { categories { name, products { name, price, stock } } }}

store { categories: [ { name: ‘Sporting Goods’, products: [ { name: ‘Football’, price:, stock: 50 }, … }, ... ]}

Single endpoint

Nested data query

Client-specified query

Data in 1 round-trip

GraphQL (cont.)REST API:

● 3 endpoints:○ Endpoint for Store○ Endpoint for Category○ Endpoint for Product

● Server-controlled query○ Query for store returns email, name, address, etc. whether you want it or not

● Multiple round-trips vs. impure-REST/endpoint proliferation○ Get Store, get each Category, get each Product in each Category○ Lumping them together creates view-specific endpoints

GraphQL Enabled

https://github.com/rmosolgo/graphql-ruby

I speak GraphQL

API Endpoint

GraphQL: Schema # app/graph/types/query_type.rb

field :store do type StoreType # Shape of this type argument :email, !types.String, "Email of Store owner" ... # Retrieve data resolve -> (obj, args, ctx) do Store.find_by_email(args[:email]) # ActiveRecord stuff endend

query { store(email: "admin@abc.com") { name, address }}

GraphQL: Schema (cont.) # app/graph/types/store_type.rb

StoreType = GraphQL::ObjectType.define do name "Store" description "Store Data" … field :name, !types.String, "Store name" # From ActiveRecord field field :address, !types.String, "Store address" # From ActiveRecord field field :categories, !types[CategoryType], “Category list” # From ActiveRecord fieldend

query { store(email: "admin@abc.com") { name, address }}

GraphQL: Schema (cont.) # app/graph/types/store_type.rb

StoreType = GraphQL::ObjectType.define do name "Store" description "Store Data" … field :name, !types.String, "Store name" # From ActiveRecord field field :address, !types.String, "Store address" # From ActiveRecord field field :categories, !types[CategoryType], “Category list” # From ActiveRecord fieldend

query { store(email: "admin@abc.com") { categories { name, products { name, price, stock } } }}

GraphQL: Schema (cont.) # app/graph/types/category_type.rb

CategoryType = GraphQL::ObjectType.define do name "Category" description "Category Data" … field :name, !types.String, "Category name" # From ActiveRecord field field :products, !types[ProductType], “Product list” # From ActiveRecord field ...end

query { store(email: "admin@abc.com") { categories { name, products { name, price, stock } } }}

GraphQL: SummarySimplify:

● Efficient request for data that you need from server endpoint

Framework

● A single API endpoint to respond to query● Query language that enables client to specify data required, ala SQL● No over-fetch● Request all data in a single query

Relay: Component-Data Co-location

Relay: Declare Data

Relay: Declare Data

React: Recap (cont.)Fetch Data (AJAX)

React: Recap (cont.)

React: Recap (cont.)

Relay: GraphQL Fetch Relay/GraphQL

Relay: Why Data Declaration? Pass All Data

GraphQL/Relay Enabled

gem ‘graphql-ruby’

I speak GraphQL/Relay

API Endpoint

gem ‘graphql-relay-ruby’Relay Layer

‘react-relay’

Relay/GraphQL on Rails

Relay/GraphQL on Rails: https://medium.com/@khor/relay-facebook-on-rails-8b4af2057152

Relay: SummarySimplify

● Data fetching related stuff○ Show ‘Loading….’○ Data re-fetching○ Caching

■ Figuring out batching, reading/writing caching, fetching only missing pieces■ NOTE: Caching is NOT new but handling caching for hierarchical data is rather new

○ Managing errors, retry failed requests○ Optimistic updates○ Pagination

Framework

● Use GraphQL to fetch all required data declaratively● Handle all the above

How To Get Started Easily?● Make one piece of UI React● Make another piece React● Repeat until SPA

Which Should I UsePartly from: https://facebook.github.io/react/blog/2015/02/20/introducing-relay-and-graphql.html

Flux Relay/GraphQL

Multiple stores (one per domain) Single store (GraphQL server)

Explicit subscription Implied subscription based on data required

Actions (possibly with AJAX) Mutations (query with changes)

REST API pros, and cons Efficient data handling (batching, caching, no over-fetching, etc.)

More customized coding Generic framework for data access, updates, etc.

Prefer imperative debugging Love magic, abstractions, and puzzle debugging

Other Stuff● React

○ Must all user-interaction go to top? Must top do all data manipulation?

● GraphQL○ Can I just use GraphQL? Do I need Relay?

● Relay○ How to modify Model without AJAX?○ There is no gem?

Thank You!

Primary ResourcesThinking in React: https://facebook.github.io/react/docs/thinking-in-react.html

Flux Best Practices: https://facebook.github.io/flux/docs/flux-utils.html

Nested Relay Components: https://facebook.github.io/react/blog/2015/03/19/building-the-facebook-news-feed-with-relay.html

Practical ResourcesRails with pure Flux: https://medium.com/@khor/back-to-front-rails-to-facebook-s-flux-ae815f81b16c

Relay/GraphQL on Rails: https://medium.com/@khor/relay-facebook-on-rails-8b4af2057152

Relay/GraphQL Rails Starter Kit: https://github.com/nethsix/relay-on-rails

ReferencesFlux Comparisons:

● https://medium.com/social-tables-tech/we-compared-13-top-flux-implementations-you-won-t-believe-who-came-out-on-top-1063db32fe73

● http://jamesknelson.com/which-flux-implementation-should-i-use-with-react/

Introduction to GraphQL: http://facebook.github.io/react/blog/2015/02/20/introducing-relay-and-graphql.html

Thinking In GraphQL: https://facebook.github.io/relay/docs/thinking-in-graphql.html

Thinking In Relay: https://facebook.github.io/relay/docs/thinking-in-relay.html