REDUX DATA FLOW WITH ANGULAR

SPAs Are Complex

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Then you make a small change…

About Me

• sparXys CEO and senior consultant

• Microsoft MVP in the last 8 years

• Pro Single Page Application Development (Apress) co-author

• 4 Microsoft Official Courses (MOCs) co-author

• GDG Rishon and AngularUP co-organizer

Agenda

• The Redux pattern

• Combining Redux and Angular

• ng2-redux library in a nutshell

Known SPA Complexity Solutions

• Command Query Responsibility Segregation (CQRS)

• Event Sourcing

• Flux

• And more

Redux

• Design pattern based on Flux• But it’s not Flux!

• Predictable state container for JavaScript apps

Redux Principles

1. Single source of truth

Single Source of Truth

• The application state is stored in an object tree within a single store

let state = store.getState();

Redux Principles

1. Single source of truth

2. State is read-only

State is Read-Only

• The only way to mutate the state is to emit an action describing what happened

store.dispatch({type: 'ADD_GROCERY_ITEM',item: { productToBuy: 'Milk' }

});

store.dispatch({type: 'REMOVE_GROCERY_ITEM',index: 3

});

Redux Principles

1. Single source of truth

2. State is read-only

3. Changes are made with pure functions

Changes Are Made with Pure Functions

• To specify how the state is transformed by actions, you write a pure function

function groceryItemReducer(state, action) {switch (action.type) {

case 'ADD_GROCERY_ITEM':return object.assign({}, state, {

groceryItems: [action.item,…state.groceryItems

]};

default:return state;

}}

Let’s drill down

Redux Actors

Action Creators

View

ReducersStore

Actions

• Plain JavaScript objects

• Include• Type – action type

• Payload – the change that should occur

let action = {type: 'ADD_GROCERY_ITEM',item: { productToBuy: 'Milk' }

};

Action Creators

Action Creators

• Functions that return actions

const ADD_GROCERY_ITEM = 'ADD_GROCERY_ITEM';

function addGroceryItem(item) {return {

type: ADD_GROCERY_ITEM,item: item

};}

Action Creators

Reducers

• Change the state in response to things that happened in the application

• Pure functions

function groceryItemReducer(state, action) {switch (action.type) {

case ADD_GROCERY_ITEM:return object.assign({}, state, {

groceryItems: [action.item,…state.groceryItems

]};

default:return state;

}}

Reducers

Store

• Only one store object

• Store data accessed through getState function

• Updates only in response to dispatching an action

import {createStore} from ‘redux’;import {groceryItemReducer} from ‘./reducers/groceryItemReducer’;

const store = createStore(groceryItemReducer);

Store

Redux Data Flow

Action Creators

View

ReducersStore

interaction (click, mouse etc.)

dispatch(action) (previous state, action)

(new state)(current state)

Redux Data Flow – Cont.

Action Creators

View

ReducersStore

interaction (click, mouse etc.)

dispatch(action) (previous state, action)

(new state)(current state)

Outside Action (push, Ajax callback

and etc.)

Redux Library API

• Redux is a small and compact library:• createStore(reducer)

• combineReducers(reducers)

• applyMiddleware(middlewares)

• compose(functions)

• bindActionCreators(creators, dispatch)

• Store API:• store.dispatch(action)

• store.getState()

• store.subscribe(listener)

DEMO: REDUX IN ACTION

Redux Middleware

• Extension point between dispatching an action and the reducer

• Middleware examples:• Logging

• Async operations

• Routing

const middleware = store => next => action => {// do something before dispatcher

let result = next(action);// do something after dispatcherreturn result;

}

const store = createStore(reducer, applyMiddleware(middleware));

DEMO: REDUX MIDDLEWARE

WHAT ABOUT ANGULAR?

Angular and Redux

• Redux can be applied in Angular oriented applications• It’s a data flow pattern

• Popular Angular & Redux libraries:• ng2-redux

• ngrx/store

NG2-REDUXhttps://github.com/angular-redux/ng2-redux

npm install --save ng2-redux

ng2-redux - Setup

• Add the module

• Create the store and provide it in the main module

import { NgReduxModule, NgRedux } from 'ng2-redux';

@NgModule({ imports: [ /* ... */, NgReduxModule ]

})

class AppModule {constructor(ngRedux: NgRedux<IAppState>) {

ngRedux.provideStore(store);}

}

ng2-redux - Usage

• Use the @select decorator and dispatch function:

class App {@select() counter: Observable<number>;

constructor(private ngRedux: NgRedux<IAppState>) {}

increment() {this.ngRedux.dispatch({ type: INCREMENT});

}}

DEMO: REDUX + ANGULAR

Summary

• Redux • Is a data flow design pattern

• Reduces complexity when building big SPAs

• Can be applied in Angular apps

Resources

• Redux:https://github.com/reactjs/redux

• ng2-redux: https://github.com/angular-redux/ng2-redux

• ngrx/store:https://github.com/ngrx/store

• My Blog – http://www.gilfink.net

• Follow me on Twitter – @gilfink

Thank You!