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Redux data flow with angular

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Gil Fink
Gil Fink

This document discusses combining Redux and Angular for managing application state. Redux is a design pattern that uses a single state tree and pure functions to update state in response to actions. It advocates for a single source of truth, read-only state, and using pure functions called reducers. The ng2-redux library makes it easy to integrate Redux into Angular applications by providing store injection and selectors to observe state changes. It recommends setting up the store and providing it to the main module, then using the @select decorator and dispatch function to access state and dispatch actions from components.

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Redux Data Flow with Angular Gil Fink sparXys CEO @gilfink / www.gilfink.net
SPAs Are Complex
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Then you make a small change…
Redux data flow with angular
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 dispatcher return 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-redux https://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
Questions?
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!

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Redux data flow with angular