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github.com/CodeSequence/ngconf2019-ngrx-workshop CLONE AND FOLLOW THE SETUP INSTRUCTIONS

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A REACTIVE STATE OF MIND WITH ANGULAR AND NGRX

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Mike Ryan @MikeRyanDev

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Mike Ryan @MikeRyanDev Software Engineer at Synapse

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Mike Ryan @MikeRyanDev Software Engineer at Synapse Google Developer Expert

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Mike Ryan @MikeRyanDev Software Engineer at Synapse Google Developer Expert NgRx Core Team

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Brandon Roberts @brandontroberts

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Brandon Roberts @brandontroberts Developer/Technical Writer

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Brandon Roberts @brandontroberts Developer/Technical Writer Angular Team

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Brandon Roberts @brandontroberts Developer/Technical Writer Angular Team NgRx Core Team

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Open source libraries for Angular

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Open source libraries for Angular Built with reactivity in mind

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Open source libraries for Angular Built with reactivity in mind State management and side effects

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Open source libraries for Angular Built with reactivity in mind State management and side effects Community driven

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DAY ONE SCHEDULE • Demystifying NgRx • Setting up the Store • Reducers • Actions • Entities • Selectors

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FORMAT 1. Concept Overview 2. Demo 3. Challenge 4. Solution

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Understand the architectural implications of NgRx and how to build Angular applications with it The Goal

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DEMYSTIFYING NGRX

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“How does NgRx work?”

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“How does NgRx work?”

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• NgRx prescribes an architecture for managing the state and side effects in you Angular application. It works by deriving a stream of updates for your application’s components called the “action stream”. • You apply a pure function called a “reducer” to the action stream as a means of deriving state in a deterministic way. • Long running processes called “effects” use RxJS operators to trigger side effects based on these updates and can optionally yield new changes back to the actions stream.

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Let’s try this a different way

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You already know how NgRx works

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COMPONENTS

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{live screenshot of movie search app}

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{live screenshot of movie search app}

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@Input() movies: Movie[]

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@Input() movie: Movie

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@Output() favorite: EventEmitter

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@Output() favoriteMovie: EventEmitter

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@Output() search: EventEmitter

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@Component({ template: ` ` }) class SearchMoviesPageComponent { movies: Movie[] = []; onSearch(searchTerm: string) { this.moviesService.findMovies(searchTerm) .subscribe(movies => { this.movies = movies; }); } }

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@Component({ template: ` ` }) class SearchMoviesPageComponent { movies: Movie[] = []; onSearch(searchTerm: string) { this.moviesService.findMovies(searchTerm) .subscribe(movies => { this.movies = movies; }); } } STATE

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@Component({ template: ` ` }) class SearchMoviesPageComponent { movies: Movie[] = []; onSearch(searchTerm: string) { this.moviesService.findMovies(searchTerm) .subscribe(movies => { this.movies = movies; }); } }

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@Component({ template: ` ` }) class SearchMoviesPageComponent { movies: Movie[] = []; onSearch(searchTerm: string) { this.moviesService.findMovies(searchTerm) .subscribe(movies => { this.movies = movies; }); } } SIDE EFFECT

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@Component({ template: ` ` }) class SearchMoviesPageComponent { movies: Movie[] = []; onSearch(searchTerm: string) { this.moviesService.findMovies(searchTerm) .subscribe(movies => { this.movies = movies; }); } }

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@Component({ template: ` ` }) class SearchMoviesPageComponent { movies: Movie[] = []; onSearch(searchTerm: string) { this.moviesService.findMovies(searchTerm) .subscribe(movies => { this.movies = movies; }); } } STATE CHANGE

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Connects data to components

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Connects data to components Triggers side effects

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Connects data to components Triggers side effects Handles state transitions

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OUTSIDE WORLD

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OUTSIDE WORLD

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OUTSIDE WORLD

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State flows down, changes flow up NGRX MENTAL MODEL

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Connects data to components Triggers side effects Handles state transitions

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Single Responsibility Principle

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Connects data to components

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@Input() and @Output()

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@Component({ selector: 'movies-list-item', }) export class MoviesListItemComponent { @Input() movie: Movie; @Output() favorite = new EventEmitter(); }

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@Component({ selector: 'movies-list-item', }) export class MoviesListItemComponent { @Input() movie: Movie; @Output() favorite = new EventEmitter(); } Does this component know who is binding to its input?

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@Component({ selector: 'movies-list-item', }) export class MoviesListItemComponent { @Input() movie: Movie; @Output() favorite = new EventEmitter(); }

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@Component({ selector: 'movies-list-item', }) export class MoviesListItemComponent { @Input() movie: Movie; @Output() favorite = new EventEmitter(); } Does this component know who is listening to its output?

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Inputs & Outputs offer Indirection

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There is indirection between consumer of state, how state changes, and side effects NGRX MENTAL MODEL

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REDUCERS CONTAINERS EFFECTS

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ACTIONS REDUCERS CONTAINERS EFFECTS

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ACTIONS REDUCERS CONTAINERS EFFECTS

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interface Action { type: string; }

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this.store.dispatch({ type: 'MOVIES_LOADED_SUCCESS', movies: [{ id: 1, title: 'Enemy', director: 'Denis Villeneuve', }], });

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Global @Output() for your whole app

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EFFECTS REDUCERS CONTAINERS EFFECTS

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EFFECTS REDUCERS CONTAINERS EFFECTS

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@Effect() findMovies$ = this.actions$ .pipe( ofType('SEARCH_MOVIES'), switchMap(action => { return this.moviesService.findMovies(action.searchTerm) .pipe( map(movies => { return { type: 'MOVIES_LOADED_SUCCESS', movies, }; }) ) }), );

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@Effect() findMovies$ = this.actions$ .pipe( ofType('SEARCH_MOVIES'), switchMap(action => { return this.moviesService.findMovies(action.searchTerm) .pipe( map(movies => { return { type: 'MOVIES_LOADED_SUCCESS', movies, }; }) ) }), );

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@Effect() findMovies$ = this.actions$ .pipe( ofType('SEARCH_MOVIES'), switchMap(action => { return this.moviesService.findMovies(action.searchTerm) .pipe( map(movies => { return { type: 'MOVIES_LOADED_SUCCESS', movies, }; }) ) }), );

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@Effect() findMovies$ = this.actions$ .pipe( ofType('SEARCH_MOVIES'), switchMap(action => { return this.moviesService.findMovies(action.searchTerm) .pipe( map(movies => { return { type: 'MOVIES_LOADED_SUCCESS', movies, }; }) ) }), );

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@Effect() findMovies$ = this.actions$ .pipe( ofType('SEARCH_MOVIES'), switchMap(action => { return this.moviesService.findMovies(action.searchTerm) .pipe( map(movies => { return { type: 'MOVIES_LOADED_SUCCESS', movies, }; }) ) }), );

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@Effect() findMovies$ = this.actions$ .pipe( ofType('SEARCH_MOVIES'), switchMap(action => { return this.moviesService.findMovies(action.searchTerm) .pipe( map(movies => { return { type: 'MOVIES_LOADED_SUCCESS', movies, }; }) ) }), );

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REDUCERS REDUCERS CONTAINERS EFFECTS

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REDUCERS REDUCERS CONTAINERS EFFECTS

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REDUCER

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REDUCER ACTIONS

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REDUCER ACTIONS INITIAL STATE

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REDUCER ACTIONS INITIAL STATE STATE

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REDUCER ACTIONS INITIAL STATE STATE

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function moviesReducer(state = [], action) { switch (action.type) { case 'MOVIES_LOADED_SUCCESS': { return action.movies; } default: { return state; } } }

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function moviesReducer(state = [], action) { switch (action.type) { case 'MOVIES_LOADED_SUCCESS': { return action.movies; } default: { return state; } } }

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function moviesReducer(state = [], action) { switch (action.type) { case 'MOVIES_LOADED_SUCCESS': { return action.movies; } default: { return state; } } }

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function moviesReducer(state = [], action) { switch (action.type) { case 'MOVIES_LOADED_SUCCESS': { return action.movies; } default: { return state; } } }

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function moviesReducer(state = [], action) { switch (action.type) { case 'MOVIES_LOADED_SUCCESS': { return action.movies; } default: { return state; } } }

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function moviesReducer(state = [], action) { switch (action.type) { case 'MOVIES_LOADED_SUCCESS': { return action.movies; } default: { return state; } } }

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function moviesReducer(state = [], action) { switch (action.type) { case 'MOVIES_LOADED_SUCCESS': { return action.movies; } default: { return state; } } }

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function moviesReducer(state = [], action) { switch (action.type) { case 'MOVIES_LOADED_SUCCESS': { return action.movies; } default: { return state; } } }

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function moviesReducer(state = [], action) { switch (action.type) { case 'MOVIES_LOADED_SUCCESS': { return action.movies; } default: { return state; } } }

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SELECTORS REDUCERS CONTAINERS EFFECTS

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SELECTORS REDUCERS CONTAINERS EFFECTS

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STORE COMPONENTS ???

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function selectMovies(state) { return state.moviesState.movies; }

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Global @Input() for your whole app

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CONTAINERS REDUCERS CONTAINERS EFFECTS

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CONTAINERS REDUCERS CONTAINERS EFFECTS

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@Component({ template: ` ` }) export class SearchMoviesPageComponent { movies$: Observable constructor(private store: Store) { this.movies$ = store.select(selectMovies); } onSearch(searchTerm: string) { this.store.dispatch({ type: 'SEARCH_MOVIES', searchTerm }); } }

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@Component({ template: ` ` }) export class SearchMoviesPageComponent { movies$: Observable constructor(private store: Store) { this.movies$ = store.select(selectMovies); } onSearch(searchTerm: string) { this.store.dispatch({ type: 'SEARCH_MOVIES', searchTerm }); } }

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@Component({ template: ` ` }) export class SearchMoviesPageComponent { movies$: Observable constructor(private store: Store) { this.movies$ = store.select(selectMovies); } onSearch(searchTerm: string) { this.store.dispatch({ type: 'SEARCH_MOVIES', searchTerm }); } }

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@Component({ template: ` ` }) export class SearchMoviesPageComponent { movies$: Observable constructor(private store: Store) { this.movies$ = store.select(selectMovies); } onSearch(searchTerm: string) { this.store.dispatch({ type: 'SEARCH_MOVIES', searchTerm }); } }

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@Component({ template: ` ` }) export class SearchMoviesPageComponent { movies$: Observable constructor(private store: Store) { this.movies$ = store.select(selectMovies); } onSearch(searchTerm: string) { this.store.dispatch({ type: 'SEARCH_MOVIES', searchTerm }); } }

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@Input() movies: Movie[] store.select(selectMovies)

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@Output() search: EventEmitter() this.store.dispatch({ type: 'SEARCH_MOVIES', searchTerm });

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Select and Dispatch are special versions of Input and Output NGRX MENTAL MODEL

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RESPONSIBILITIES

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Containers connect data to components RESPONSIBILITIES

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Containers connect data to components Effects triggers side effects RESPONSIBILITIES

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Containers connect data to components Effects triggers side effects Reducers handle state transitions RESPONSIBILITIES

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Delegate responsibilities to individual modules of code NGRX MENTAL MODEL

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State flows down, changes flow up

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State flows down, changes flow up Indirection between state & consumer

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State flows down, changes flow up Indirection between state & consumer Select & Dispatch => Input & Output

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State flows down, changes flow up Indirection between state & consumer Select & Dispatch => Input & Output Adhere to single responsibility principle

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github.com/CodeSequence/ngconf2019-ngrx-workshop

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Demo

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1. Clone the repo at 
 https://github.com/CodeSequence/ngconf2019-ngrx-workshop 2. Checkout the challenge branch 3. Familiarize yourself with the file structure 4. Where is movies state handled? 5. Where are the movies actions located? 6. How does the movies state flow into the movies component? 7. How are events in the movies component going to the movies reducer? Challenge github.com/CodeSequence/ngconf2019-ngrx-workshop Branch: challenge

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SETTING UP THE STORE

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State contained in a single state tree State in the store is immutable Slices of state are updated with reducers STORE

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export interface MoviesState { activeMovieId: string | null; movies: Movie[]; }

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export const initialState: MoviesState = { activeMovieId: null, movies: initialMovies, };

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export function moviesReducer( state = initialState, action: Action ): MoviesState { switch (action.type) { default: return state; } }

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import * as fromMovies from “./movies/movies.reducer”; import * as fromBooks from “./books/books.reducer”; export interface AppState { movies: fromMovies.MoviesState; books: fromBooks.BooksState; } export const reducers: ActionReducerMap = { movies: fromMovies.reducer, books: fromBooks.reducer };

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@NgModule({ imports: [ // imports … StoreModule.forRoot(reducers), StoreDevtoolsModule.instrument({ maxAge: 5 }), ], }) export class AppModule {}

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export class MoviesComponent implements OnInit { movies$: Observable; constructor(private store: Store) { this.movies$ = store.select( (state: AppState) => state.movies ); } }

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STATE FLOWS DOWN

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Demo

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1. Open books.reducer.ts 2. Define an interface for BooksState that has activeBookId and books properties 3. Define an initialState object that implements the BooksState interface 4. Create a reducer that defaults to initialState with a default case in a switch statement that returns state Challenge, pt 1 PR: 00-setup github.com/CodeSequence/ngconf2019-ngrx-workshop

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1. Open shared/state/index.ts and add books to the State interface and the books reducer to the reducers object 2. Open books-page.component.ts and inject the Store service into the constructor 3. Add an observable property to the component that gets all of the books from state using the select operator 4. Update books-page.component.html to use the async pipe to get the list of books Challenge, pt 2 PR: 00-setup github.com/CodeSequence/ngconf2019-ngrx-workshop

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REDUCERS

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Produce new states Receive the last state and next action Switch on the action type REDUCERS Use pure, immutable operations

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export function reducer(state = initialState, action: Action): MoviesState { switch (action.type) { case "select": return { activeMovieId: action.movieId, movies: state.movies }; case "create": return { activeMovieId: state.selectedMovieId, movies: createMovie(state.movies, action.movie) }; default: return state; } }

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const createMovie = (movies, movie) => [ ...movies, movie ]; const updateMovie = (movies, movie) => movies.map(w => { return w.id === movie.id ? Object.assign({}, movie, w) : w; }); const deleteMovie = (movies, movie) => movies.filter(w => movie.id !== w.id);

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class MoviesComponent { createMovie(movie) { this.store.dispatch({ type: "create", movie }); } }

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Demo

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1. Update the books reducer to handle “select”, “clear select”, “create”, “update”, and “delete” actions 2. Use the helper functions already in books.reducer.ts 3. Update books-page.component.ts to dispatch “select”, “clear select”, “create”, “update”, and “delete” actions from the component 4. Remove the BooksService from the component Challenge PR: 01-reducers github.com/CodeSequence/ngconf2019-ngrx-workshop

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ACTIONS

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Unified interface to describe events Just data, no functionality Has at a minimum a type property ACTIONS Strongly typed using classes and enums

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Unique events get unique actions Actions are grouped by their source Actions are never reused GOOD ACTION HYGIENE

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class MoviesComponent { createMovie(movie) { this.store.dispatch({ type: "create", movie }); } }

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export enum MoviesActionTypes { SelectMovie = "[Movies Page] Select Movie”, AddMovie = "[Movies Page] Add Movie", UpdateMovie = "[Movies Page] Update Movie", DeleteMovie = "[Movies Page] Delete Movie” }

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export class SelectMovie implements Action { readonly type = MoviesActionTypes.SelectMovie; constructor(public movie) {} }

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export class AddMovie implements Action { readonly type = MoviesActionTypes.AddMovie; constructor(public movie: MovieModel) {} } export class UpdateMovie implements Action { readonly type = MoviesActionTypes.UpdateMovie; constructor(public movie: MovieModel) {} } export class DeleteMovie implements Action { readonly type = MoviesActionTypes.DeleteMovie; constructor(public movie: MovieModel) {} }

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export type MoviesActions = | SelectMovie | AddMovie | UpdateMovie | DeleteMovie;

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export function moviesReducer( state = initialState, action: MoviesActions ): MoviesState { switch (action.type) { case MoviesActionTypes.MovieSelected: ... case MoviesActionTypes.AddMovie: ... case MoviesActionTypes.UpdateMovie: ... case MoviesActionTypes.DeleteMovie: ... default: return state; } }

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createMovie(movie) { this.store.dispatch({ type: "create", movie }); }

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createMovie(movie) { this.store.dispatch(new MoviesActions.AddMovie(movie)); }

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Demo

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1. Open books-page.actions.ts and create an enum to hold the various action types 2. Create strongly typed actions that adhere to good action hygiene for selecting a book, clearing the selection, creating a book, updating a book, and deleting a book. 3. Export the actions as a union type 4. Update books-page.components.ts and books.reducer.ts to use the new actions Challenge PR: 02-actions github.com/CodeSequence/ngconf2019-ngrx-workshop

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ENTITIES

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Working with collections should be fast Collections are very common Common set of basic state operations ENTITY Common set of basic state derivations

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interface EntityState { ids: string[] | number[]; entities: { [id: string | number]: Model }; }

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export interface MoviesState extends EntityState { activeMovieId: string | null; } export const adapter = createEntityAdapter(); export const initialState: Movie = adapter.getInitialState( { activeMovieId: null } );

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export interface MoviesState extends EntityState { activeMovieId: string | null; } export const adapter = createEntityAdapter(); export const initialState: Movie = adapter.getInitialState( { activeMovieId: null } );

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export interface MoviesState extends EntityState { activeMovieId: string | null; } export const adapter = createEntityAdapter(); export const initialState: Movie = adapter.getInitialState( { activeMovieId: null } );

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export interface MoviesState extends EntityState { activeMovieId: string | null; } export const adapter = createEntityAdapter(); export const initialState: Movie = adapter.getInitialState( { activeMovieId: null } );

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case MoviesActionTypes.AddMovie: return { activeMovieId: state.selectedMovieId, movies: createMovie(state.movies, action.movie) };

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case MoviesActionTypes.AddMovie: return adapter.addOne(action.movie, state);

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this.movies$ = store.select((state: any) => state.movies.ids.map(id => state.movies.entities[id]) );

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Demo

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1. Add an “Enter” action to books-page.actions.ts and dispatch it in the getBooks() method of books.component.ts 2. Update books.reducer.ts to use EntityState to define BooksState 3. Create an unsorted entity adapter for BooksState and use it to initialize initialState 4. Update the reducer to use the adapter methods 5. Add a case statement for the “Enter” action that adds all of the initialBooks to the state 6. Update the books$ selector in books-page.component.ts to use the ids and entities properties of the books state to get the list of books Challenge PR: 03-entity github.com/CodeSequence/ngconf2019-ngrx-workshop

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SELECTORS

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Allow us to query our store for data Recompute when their inputs change Fully leverage memoization for performance SELECTORS Selectors are fully composable

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export const selectActiveMovieId = (state: MoviesState) => state.activeMovieId; // get and export the selectors export const { selectIds, selectEntities, selectAll } = adapter.getSelectors();

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export const selectActiveMovie = createSelector( selectActiveMovieId, selectEntities, (activeMovieId, movieEntities) => movieEntities[activeMovieId], );

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export const selectMoviesState = (state: AppState) => state.movies; export const selectAllMovies = createSelector( selectMoviesState, fromMovies.selectAll, ); export const selectActiveMovie = createSelector( selectMoviesState, fromMovies.selectActiveMovie, );

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this.movies$ = store.select((state: any) => state.movies.ids.map(id => state.movies.entities[id]) );

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this.movies$ = store.select(selectAllMovies);

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Demo

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1. Open books.reducer.ts and use the entity adapter to create selectors for selectAll and selectEntities 2. Write a selector in books.reducer.ts that gets activeBookId 3. Use createSelector to create a selectActiveBook selector using selectEntities and selectActiveBookId 4. Use createSelector to create a selectEarningsTotal selector to calculate the gross total earnings of all books using selectAll 5. Create global versions of selectAllBooks, selectActiveBook, and selectBookEarningsTotal in state/index.ts using createSelector 6. Update books-page.component.ts and its template to use the selectAllBooks, selectActiveBook, and selectEarningsTotal selectors Challenge PR: 04-selectors github.com/CodeSequence/ngconf2019-ngrx-workshop

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State flows down, changes flow up

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State flows down, changes flow up Indirection between state & consumer

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State flows down, changes flow up Indirection between state & consumer Select & Dispatch => Input & Output

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State flows down, changes flow up Indirection between state & consumer Select & Dispatch => Input & Output Adhere to single responsibility principle

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State contained in a single state tree State in the store is immutable Slices of state are updated with reducers STORE

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Produce new states Receive the last state and next action Switch on the action type REDUCERS Use pure, immutable operations

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Unified interface to describe events Just data, no functionality Has at a minimum a type property ACTIONS Strongly typed using classes and enums

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Working with collections should be fast Collections are very common Common set of basic state operations ENTITY Common set of basic state derivations

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Allow us to query our store for data Recompute when their inputs change Fully leverage memoization for performance SELECTORS Selectors are fully composable

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DAY TWO SCHEDULE • Effects++ • Advanced Actions • Testing Reducers • Testing Effects • Wrap Up

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github.com/CodeSequence/ngconf2019-ngrx-workshop CLONE AND FOLLOW THE SETUP INSTRUCTIONS

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A REACTIVE STATE OF MIND WITH ANGULAR AND NGRX

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Mike Ryan @MikeRyanDev

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Mike Ryan @MikeRyanDev Software Engineer at Synapse

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Mike Ryan @MikeRyanDev Software Engineer at Synapse Google Developer Expert

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Mike Ryan @MikeRyanDev Software Engineer at Synapse Google Developer Expert NgRx Core Team

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Brandon Roberts @brandontroberts

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Brandon Roberts @brandontroberts Developer/Technical Writer

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Brandon Roberts @brandontroberts Developer/Technical Writer Angular Team

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Brandon Roberts @brandontroberts Developer/Technical Writer Angular Team NgRx Core Team

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State flows down, changes flow up

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State flows down, changes flow up Indirection between state & consumer

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State flows down, changes flow up Indirection between state & consumer Select & Dispatch => Input & Output

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State flows down, changes flow up Indirection between state & consumer Select & Dispatch => Input & Output Adhere to single responsibility principle

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REDUCERS CONTAINERS EFFECTS

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REDUCERS CONTAINERS EFFECTS

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1. Clone the repo at 
 https://github.com/CodeSequence/ngconf2019-ngrx-workshop 2. Checkout the 04-selectors branch 3. Familiarize yourself with the file structure 4. Where is books state handled? 5. Where are the books actions located? 6. How does the books state flow into the movies component? 7. How are events in the books page component going to the books reducer? Challenge github.com/CodeSequence/ngconf2019-ngrx-workshop Branch: 04-selectors

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EFFECTS

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REDUCERS CONTAINERS EFFECTS

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REDUCERS CONTAINERS EFFECTS

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Processes that run in the background Connect your app to the outside world Often used to talk to services EFFECTS Written entirely using RxJS streams

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export enum MoviesApiActionTypes { MoviesLoaded = ‘[Movies API] Movies Loaded', MovieAdded = ‘[Movies API] Movie Added', MovieUpdated = ‘[Movies API] Movie Updated', MovieDeleted = ‘[Movies API] Movie Deleted' }

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@Injectable() export class MoviesEffects { constructor( private actions$: Actions< BooksPageActions.BooksActions >, private moviesService: MoviesService ) {} }

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export class MoviesEffects { @Effect() loadMovies$ = this.actions$.pipe( ofType(MoviesActionTypes.LoadMovies), mergeMap(() => this.moviesService.all().pipe( map( (res: MovieModel[]) => new MovieApiActions.MoviesLoaded(res) ), catchError(() => EMPTY) ) ) ); }

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export class MoviesEffects { @Effect() loadMovies$ = this.actions$.pipe( ofType(MoviesActionTypes.LoadMovies), mergeMap(() => this.moviesService.all().pipe( map( (res: MovieModel[]) => new MovieApiActions.MoviesLoaded(res) ), catchError(() => EMPTY) ) ) ); }

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export class MoviesEffects { @Effect() loadMovies$ = this.actions$.pipe( ofType(MoviesActionTypes.LoadMovies), mergeMap(() => this.moviesService.all().pipe( map( (res: MovieModel[]) => new MovieApiActions.MoviesLoaded(res) ), catchError(() => EMPTY) ) ) ); }

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export class MoviesEffects { @Effect() loadMovies$ = this.actions$.pipe( ofType(MoviesActionTypes.LoadMovies), mergeMap(() => this.moviesService.all().pipe( map( (res: MovieModel[]) => new MovieApiActions.MoviesLoaded(res) ), catchError(() => EMPTY) ) ) ); }

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EffectsModule.forFeature([MoviesEffects]);

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const BASE_URL = "http://localhost:3000/movies"; @Injectable({ providedIn: "root" }) export class MoviesService { constructor(private http: HttpClient) {} load(id: string) { return this.http.get(`${BASE_URL}/${id}`); } }

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export function moviesReducer( state = initialState, action: MoviesActions | MoviesApiActions): MoviesState { switch (action.type) { case MoviesApiActionTypes.MoviesLoaded: return adapter.addAll(action.movies, state); case MoviesApiActionTypes.MovieAdded: return adapter.addOne(action.movie, state); case MoviesActions.UpdateMovie: return adapter.upsertOne(action.movie, state); case MoviesActions.DeleteMovie: return adapter.removeOne(action.movie.id, state); default: return state; } }

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Demo

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1. Update books-api.actions.ts to export an action for BooksLoaded along with an action union type 2. Create a file at app/books/books-api.effects.ts and add an effect class to it with an effect called loadBooks$ that calls BooksService.all() and maps the result into a BooksLoaded action 3. Register the effect using EffectsModule.forFeature([]) in books.module.ts 4. Update the books reducer to handle the BooksLoaded action by replacing the Enter action handler Challenge PR: 05-effects github.com/CodeSequence/ngconf2019-ngrx-workshop

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ADVANCED EFFECTS

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export class MoviesEffects { @Effect() loadMovies$ = this.actions$.pipe( ofType(MoviesActionTypes.LoadMovies), mergeMap(() => this.moviesService.all().pipe( map( (res: MovieModel[]) => new MovieApiActions.MoviesLoaded(res) ), catchError(() => EMPTY) ) ) ); }

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export class MoviesEffects { @Effect() loadMovies$ = this.actions$.pipe( ofType(MoviesActionTypes.LoadMovies), mergeMap(() => this.moviesService.all().pipe( map( (res: MovieModel[]) => new MovieApiActions.MoviesLoaded(res) ), catchError(() => EMPTY) ) ) ); }

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WHAT MAP OPERATOR SHOULD I USE?

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Subscribe immediately, never cancel or discard mergeMap Subscribe after the last one finishes concatMap Discard until the last one finishes exhaustMap Cancel the last one if it has not completed switchMap

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Subscribe immediately, never cancel or discard mergeMap Discard until the last one finishes exhaustMap Cancel the last one if it has not completed switchMap RACE CONDITIONS!

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CONCATMAP IS THE SAFEST OPERATOR …but there is a risk of back pressure

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https://stackblitz.com/edit/angular-kbvxzz BACKPRESSURE DEMO

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Deleting items mergeMap Updating or creating items concatMap Non-parameterized queries exhaustMap Parameterized queries switchMap

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@Effect() enterMoviesPage$ = this.actions$.pipe( ofType(MoviesPageActions.Types.Enter), exhaustMap(() => this.movieService.all().pipe( map(movies => new MovieApiActions.LoadMoviesSuccess(movies)), catchError(() => of(new MovieApiActions.LoadMoviesFailure())) ) ) );

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@Effect() updateMovie$ = this.actions$.pipe( ofType(MoviesPageActions.Types.UpdateMovie), concatMap(action => this.movieService.update(action.movie.id, action.changes).pipe( map(movie => new MovieApiActions.UpdateMovieSuccess(movie)), catchError(() => of(new MovieApiActions.UpdateMovieFailure(action.movie)) ) ) ) );

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Demo

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1. Add “Book Created”, “Book Updated”, and “Book Deleted” actions to books- api.actions.ts and update books.reducer.ts to handle these new actions 2. Open books-api.effects.ts and update the loadBooks$ effect to use the exhaustMap operator 3. Add an effect for creating a book using the BooksService.create() method and the concatMap operator 4. Add an effect for updating a book using the BooksService.update() method and the concatMap operator 5. Add an effect for deleting a book using the BooksService.delete() method and the mergeMap operator Challenge PR: 06-advanced-effects github.com/CodeSequence/ngconf2019-ngrx-workshop

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ADVANCED ACTIONS

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import { Action } from "@ngrx/store"; import { Book } from "src/app/shared/models/book.model"; export enum BooksApiActionTypes { BooksLoaded = "[Books API] Books Loaded Success", BookCreated = "[Books API] Book Created", BookUpdated = "[Books API] Book Updated", BookDeleted = "[Books API] Book Deleted" } export class BooksLoaded implements Action { readonly type = BooksApiActionTypes.BooksLoaded; constructor(public books: Book[]) {} } export class BookCreated implements Action { readonly type = BooksApiActionTypes.BookCreated; constructor(public book: Book) {} } export class BookUpdated implements Action { readonly type = BooksApiActionTypes.BookUpdated; constructor(public book: Book) {} } export class BookDeleted implements Action { readonly type = BooksApiActionTypes.BookDeleted; constructor(public book: Book) {} } export type BooksApiActions = | BooksLoaded | BookCreated | BookUpdated | BookDeleted;

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import { Action } from "@ngrx/store"; import { Book } from "src/app/shared/models/book.model"; export enum BooksApiActionTypes { BooksLoaded = "[Books API] Books Loaded Success", BookCreated = "[Books API] Book Created", BookUpdated = "[Books API] Book Updated", BookDeleted = "[Books API] Book Deleted" } export class BooksLoaded implements Action { readonly type = BooksApiActionTypes.BooksLoaded;

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import { Action } from "@ngrx/store"; import { Book } from "src/app/shared/models/book.model"; export enum BooksApiActionTypes { BooksLoaded = "[Books API] Books Loaded Success", BookCreated = "[Books API] Book Created", BookUpdated = "[Books API] Book Updated", BookDeleted = "[Books API] Book Deleted" } export class BooksLoaded implements Action { readonly type = BooksApiActionTypes.BooksLoaded;

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import { Action } from "@ngrx/store"; import { Book } from "src/app/shared/models/book.model"; export enum BooksApiActionTypes { BooksLoaded = "[Books API] Books Loaded Success", BookCreated = "[Books API] Book Created", BookUpdated = "[Books API] Book Updated", BookDeleted = "[Books API] Book Deleted" } export class BooksLoaded implements Action { readonly type = BooksApiActionTypes.BooksLoaded;

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export class BooksLoaded implements Action { readonly type = BooksApiActionTypes.BooksLoaded; constructor(public books: Book[]) {} } export class BookCreated implements Action { readonly type = BooksApiActionTypes.BookCreated; constructor(public book: Book) {} } export class BookUpdated implements Action { readonly type = BooksApiActionTypes.BookUpdated;

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export class BooksLoaded implements Action { readonly type = BooksApiActionTypes.BooksLoaded; constructor(public books: Book[]) {} } export class BookCreated implements Action { readonly type = BooksApiActionTypes.BookCreated; constructor(public book: Book) {} } export class BookUpdated implements Action { readonly type = BooksApiActionTypes.BookUpdated;

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export class BooksLoaded implements Action { readonly type = BooksApiActionTypes.BooksLoaded; constructor(public books: Book[]) {} } export class BookCreated implements Action { readonly type = BooksApiActionTypes.BookCreated; constructor(public book: Book) {} } export class BookUpdated implements Action { readonly type = BooksApiActionTypes.BookUpdated;

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export const loadMoviesFailure = createAction( "[Movies API] Load Movies Failure" ); MovieApiActions.loadMoviesFailure();

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export const updateMovieSuccess = createAction( "[Movies API] Update Movie Success", props<{ movie: Movie }>() ); MovieApiActions.updateMoviesSuccess({ movie });

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export type Union = ReturnType< | typeof loadMoviesSuccess | typeof loadMoviesFailure // ... >;

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@Effect() enterMoviesPage$ = this.actions$.pipe( ofType(MoviesPageActions.enter.type), exhaustMap(() => this.movieService.all().pipe( map(movies => MovieApiActions.loadMoviesSuccess({ movies })), catchError(() => of(MovieApiActions.loadMoviesFailure())) ) ) );

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export function reducer( state: State = initialState, action: MovieApiActions.Union | MoviesPageActions.Union ): State { switch (action.type) { case MoviesPageActions.enter.type: { return { ...state, activeMovieId: null }; } default: { return state; } } }

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Demo

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1. Update books-page.actions.ts to use the createAction helper and the props factory function 2. Use the ReturnType utility type to replace the action union 3. Update books-api.actions.ts to use the createAction helper and the props factory function 4. Use the ReturnType utility type to replace the action union 5. Update books-page.component.ts, books-api.effects.ts, and books.reducer.ts to use the new action format Challenge PR: 07-action-creators github.com/CodeSequence/ngconf2019-ngrx-workshop

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EFFECTS EXAMPLES

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@Effect() tick$ = interval(/* Every minute */ 60 * 1000).pipe( map(() => Clock.tickAction(new Date())) );

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@Effect() = fromWebSocket(“/ws").pipe(map(message => { switch (message.kind) { case “book_created”: { return WebSocketActions.bookCreated(message.book); } case “book_updated”: { return WebSocketActions.bookUpdated(message.book); } case “book_deleted”: { return WebSocketActions.bookDeleted(message.book); } } }))

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@Effect() createBook$ = this.actions$.pipe( ofType(BooksPageActions.createBook.type), mergeMap(action => this.booksService.create(action.book).pipe( map(book => BooksApiActions.bookCreated({ book })), catchError(error => of(BooksApiActions.createFailure({ error, book: action.book, }))) ) ) );

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@Effect() promptToRetry$ = this.actions$.pipe( ofType(BooksApiActions.createFailure), mergeMap(action => this.snackBar .open("Failed to save book.", "Try Again", { duration: /* 12 seconds */ 12 * 1000 }) .onAction() .pipe( map(() => BooksApiActions.retryCreate(action.book)) ) ) );

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@Effect() promptToRetry$ = this.actions$.pipe( ofType(BooksApiActions.createFailure), mergeMap(action => this.snackBar .open("Failed to save book.", "Try Again", { duration: /* 12 seconds */ 12 * 1000 }) .onAction() .pipe( map(() => BooksApiActions.retryCreate(action.book)) ) ) ); Failed to save book. TRY AGAIN

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@Effect() createBook$ = this.actions$.pipe( ofType( BooksPageActions.createBook, BooksApiActions.retryCreate, ), mergeMap(action => this.booksService.create(action.book).pipe( map(book => BooksApiActions.bookCreated({ book })), catchError(error => of(BooksApiActions.createFailure({ error, book: action.book, }))) ) ) );

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@Effect({ dispatch: false }) openUploadModal$ = this.actions$.pipe( ofType(BooksPageActions.openUploadModal), tap(() => { this.dialog.open(BooksCoverUploadModalComponent); }) );

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@Effect() uploadCover$ = this.actions$.pipe( ofType(BooksPageActions.uploadCover), concatMap(action => this.booksService.uploadCover(action.cover).pipe( map(result => BooksApiActions.uploadComplete(result)), takeUntil( this.actions$.pipe( ofType(BooksPageActions.cancelUpload) ) ) ) ) );

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Testing Reducers TESTING REDUCERS

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it("should return the initial state when initialized", () => { const state = reducer(undefined, { type: "@@init" } as any); expect(state).toBe(initialState); });

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const movies: Movie[] = [ { id: "1", name: "Green Lantern", earnings: 0 } ]; const action = MovieApiActions.loadMoviesSuccess({ movies }); const state = reducer(initialState, action);

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const movie: Movie = { id: "1", name: "mother!", earnings: 1000 }; const firstAction = MovieApiActions.createMovieSuccess({ movie }); const secondAction = MoviesPageActions.deleteMovie({ movie }); const state = [firstAction, secondAction].reduce( reducer, initialState );

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const movies: Movie[] = [ { id: "1", name: "Green Lantern", earnings: 0 } ]; const action = MovieApiActions.loadMoviesSuccess({ movies }); const state = reducer(initialState, action); expect(selectAllMovies(state)).toEqual(movies);

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expect(state).toEqual({ ids: ["1"], entities: { "1": { id: "1", name: "Green Lantern", earnings: 0 } } });

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SNAPSHOT TESTING

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expect(state).toMatchSnapshot();

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exports[ `Movie Reducer should load all movies when the API loads them all successfully 1` ] = ` Object { "activeMovieId": null, "entities": Object { "1": Object { "earnings": 0, "id": "1", "name": "Green Lantern", }, }, "ids": Array [ "1", ], } `; in: shared/state/__snapshots__/movie.reducer.spec.ts.snap

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Avoid writing out manual assertions Verify how state transitions impact state Can be used with components SNAPSHOT TESTING Creates snap files that get checked in

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Demo

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1. Write a test that verifies the books reducer returns the initial state when no state is provided using the toBe matcher 2. Write tests that verifies the books reducer correctly transitions state for loading all books, creating a book, and deleting a book using the toMatchSnapshot matcher 3. Write tests that verifies the behavior of the selectActiveBook and selectAll selectors Challenge PR: 08-reducer-testing github.com/CodeSequence/ngconf2019-ngrx-workshop

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TESTING EFFECTS

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OBSERVABLE TIMELINES

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import { timer } from "rxjs"; import { mapTo } from "rxjs/operators"; timer(50).pipe(mapTo("a"));

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timer(50).pipe(mapTo("a")); -----a|

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timer(30).pipe(mergeMap(() => throwError(‘Error!'))) ---#

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const source$ = timer(50).pipe(mapTo("a")); const expected$ = cold("-----a|"); expect(source$).toBeObservable(expected$);

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const source$ = timer(30).pipe( mergeMap(() => throwError("Error!")) ); const expected$ = cold("---#", {}, "Error!"); expect(source$).toBeObservable(expected$);

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10ms of time - Emission of any value a b c … Error # Completion |

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COLD AND HOT OBSERVABLES

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Cable TV COLD HOT

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Hot Observable Actions Cold Observables HttpClient Hot Observable Store Cold Observable fromWebSocket

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let actions$: Observable; beforeEach(() => { TestBed.configureTestingModule({ providers: [provideMockActions(() => actions$)] }); }); actions$ = hot("---a---", { a: BooksPageActions.enter });

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const inputAction = MoviesPageActions.createMovie({ movie: { name: mockMovie.name, earnings: 25 } }); const outputAction = MovieApiActions.createMovieSuccess({ movie: mockMovie }); actions$ = hot("--a---", { a: inputAction }); const response$ = cold("--b|", { b: mockMovie }); const expected$ = cold("----c--", { c: outputAction }); mockMovieService.create.mockReturnValue(response$); expect(effects.createMovie$).toBeObservable(expected$);

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Make assertions about time Describe Rx behavior with diagrams Verify observables behave as described JASMINE MARBLES Works with hot and cold observables

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Demo

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1. Open books-api.effects.spec.ts and declare variables for the actions$, instance of the effects, and a mock bookService 2. Use the TestBed to setup providers for the effects, actions, and the book service 3. Verify the behavior of the createBook$ effect using mock actions and test observables Challenge PR: 09-effects-testing github.com/CodeSequence/ngconf2019-ngrx-workshop

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FOLDER LAYOUT

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Locating our code is easy Identify code at a glance Flat file structure for as long as possible LIFT Try to stay DRY - don’t repeat yourself

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src/ shared/ // Shared code modules/ ${feature}/ // Feature code

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modules/ ${feature}/ actions/ ${action-category}.actions.ts index.ts components/ ${component-name}/ ${component-name}.component.ts ${component-name}.component.spec.ts services/ ${service-name}.service.ts ${service-name}.service.spec.ts effects/ ${effect-name}.effects.ts ${effect-name}.effects.spec.ts ${feature}.module.ts

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modules/ book-collection/ actions/ books-page.actions.ts index.ts components/ books-page/ books-page.component.ts books-page.component.spec.ts services/ books.service.ts books.service.spec.ts effects/ books.effects.ts books.effects.spec.ts book-collection.module.ts

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import * as BooksPageActions from "./books-page.actions"; import * as BooksApiActions from "./books-api.actions"; export { BooksPageActions, BooksApiActions }; ACTION BARRELS

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import { BooksPageActions } from "app/modules/book-collection/actions";

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src/ shared/ state/ ${state-name}/ ${state-key}/ ${state-key}.reducer.ts ${state-key}.spec.ts index.ts ${feature-name}.state.ts ${feature-name}.state.spec.ts ${feature-name}.state.module.ts index.ts effects/ ${effect-name}/ ${effect-name}.effects.ts ${effect-name}.effects.spec.ts ${effect-name}.actions.ts ${effect-name}.module.ts index.ts

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src/ shared/ state/ core/ books/ books.reducer.ts books.spec.ts core.state.ts core.state.spec.ts core.state.module.ts index.ts effects/ clock/ clock.effects.ts clock.effects.spec.ts clock.actions.ts clock.module.ts

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Put state in a shared place separate from features Effects, components, and actions belong to features Some effects can be shared FOLDER STRUCTURE Reducers reach into modules’ action barrels

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“How does NgRx work?”

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“How does NgRx work?”

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State flows down, changes flow up

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State flows down, changes flow up Indirection between state & consumer

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State flows down, changes flow up Indirection between state & consumer Select & Dispatch => Input & Output

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State flows down, changes flow up Indirection between state & consumer Select & Dispatch => Input & Output Adhere to single responsibility principle

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State contained in a single state tree State in the store is immutable Slices of state are updated with reducers STORE

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Produce new states Receive the last state and next action Switch on the action type REDUCERS Use pure, immutable operations

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Unified interface to describe events Just data, no functionality Has at a minimum a type property ACTIONS Strongly typed using createAction

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Working with collections should be fast Collections are very common Common set of basic state operations ENTITY Common set of basic state derivations

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Processes that run in the background Connect your app to the outside world Often used to talk to services EFFECTS Written entirely using RxJS streams

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Avoid writing out manual assertions Verify how state transitions impact state Can be used with components SNAPSHOT TESTING Creates snap files that get checked in

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Make assertions about time Describe Rx behavior with diagrams Verify observables behave as described JASMINE MARBLES Works with hot and cold observables

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“How does NgRx work?”

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“How does NgRx work?”

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HELP US IMPROVE https://bit.ly/2ROXvn0

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FOLLOW ON TALKS “Good Action Hygiene” by Mike Ryan https://youtu.be/JmnsEvoy-gY “Reactive Testing Strategies with NgRx” by Brandon Roberts & Mike Ryan https://youtu.be/MTZprd9tI6c “Authentication with NgRx” by Brandon Roberts https://youtu.be/46IRQgNtCGw “You Might Not Need NgRx” by Mike Ryan https://youtu.be/omnwu_etHTY “Just Another Marble Monday” by Sam Brennan & Keith Stewart https://youtu.be/dwDtMs4mN48

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@ngrx/schematics

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@ngrx/schematics @ngrx/router-store

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@ngrx/schematics @ngrx/router-store @ngrx/data

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@ngrx/schematics @ngrx/router-store @ngrx/data ngrx.io

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@MikeRyanDev @brandontroberts

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THANK YOU