@ngxp/store-service
Adds an abstraction layer between Angular components and the @ngrx store and effects. This decouples the components from the store, selectors, actions and effects and makes it easier to test components.
Table of contents
Installation
Get the latest version from NPM
npm install @ngxp/store-serviceComparison
Before
Component
import { Component } from '@angular/core';
import { Observable } from 'rxjs';
import { Book } from 'src/app/shared/books/book.model';
// Tight coupling to ngrx, state model, selectors and actions
import { Store } from '@ngrx/store';
import { Actions, ofType } from '@ngrx/effects';
import { AppState } from 'src/app/store/appstate.model';
import { getAllBooks, getBook } from 'src/app/store/books/books.selectors';
import { addBookAction, booksLoadedAction } from 'src/app/store/books/books.actions';
@Component({
selector: 'nss-book-list',
templateUrl: './book-list.component.html',
styleUrls: ['./book-list.component.scss']
})
export class BookListComponent {
books$: Observable<Book[]>;
book$: Observable<Book>;
booksLoaded: boolean = false;
constructor(
private store: Store<AppState>
private actions: Actions
) {
this.books$ = this.store.select(getAllBooks);
this.book$ = this.store.select(getBook, { id: 0 });
this.actions
.pipe(
ofType(booksLoadedAction),
map(() => this.loaded = true)
)
.suscribe();
}
addBook(book: Book) {
this.store.dispatch(addBookAction({ book }));
}
}After
Component
import { Component } from '@angular/core';
import { Observable } from 'rxjs';
import { Book } from 'src/app/shared/books/book.model';
import { BookStoreService } from 'src/app/shared/books/book-store.service';
// Reduced to just one dependency. Loose coupling
@Component({
selector: 'nss-book-list',
templateUrl: './book-list.component.html',
styleUrls: ['./book-list.component.scss']
})
export class BookListComponent {
books$: Observable<Book[]>;
book$: Observable<Book>;
booksLoaded: boolean = false;
constructor(
private bookStore: BookStoreService // <- StoreService
) {
this.books$ = this.bookStore.getAllBooks(); // <- Selector
this.book$ = this.bookStore.getBook({ id: 0 }); // <- Selector
this.bookStore.booksLoaded$ // <-- Observer / Action stream of type
.pipe(
map(() => this.loaded = true)
)
.subscribe();
}
addBook(book: Book) {
this.bookStore.addBook({ book }); // <- Action
}
}BookStoreService
import { Injectable } from '@angular/core';
import { select, StoreService, dispatch, observe } from '@ngxp/store-service';
import { Book } from 'src/app/shared/books/book.model';
import { getBooks } from 'src/app/store/books/books.selectors';
import { State } from 'src/app/store/store.model';
import { addBookAction, booksLoadedAction } from 'src/app/store/books/books.actions';
@Injectable()
export class BookStoreService extends StoreService<State> {
getAllBooks = select(getBooks); // <- Selector
getBook = select(getBook); // <- Selector
addBook = dispatch(addBookAction); // <- Action
booksLoaded$ = observe([booksLoadedAction]); // <- Observer / Action stream
}Documentation
StoreService
The BookStoreService Injectable class has to extend the StoreService<State> class where State is your ngrx state model.
import { StoreService } from '@ngxp/store-service';
import { AppState } from 'app/store/state.model';
@Injectable()
export class BookStoreService extends StoreService<AppState> {
...
}Selectors
To use selectors you wrap the ngrx selector inside the select(...) function:
// Define the selector function
export const selectAllBooks = createSelector(
(state: State) => state.books;
};
//Or with props
export const selectBook = createSelector(
(state: State, props: { id: number }) => state.books[id];
};
...
// Use the selector function inside the select(...) function
allBooks = select(selectAllBooks); // () => Observable<Book[]>
book = select(selectBook); // (props: { id: number }) => Observable<Book>The select(...) function automatically infers the correct typing according to the props and return type of the selector.
Actions
To dispatch actions add a property with the dispatch(...) function.
// Defined the Action as a class
export const loadBooksAction = createAction('[Books] Load books');
export const addBookAction = createAction('[Books] Add book' props<{ book: Book}>())
...
loadBooks = dispatch(loadBooksAction); // () => void
addBook = dispatch(addBookAction); // (props: { book: Book }) => voidThe dispatch(...) function automatically infers the parameters according to the props of the action.
Observers
Observers are a way to listen for specific action types on the Actions stream from @ngrx/effects.
booksLoaded$ = observe([booksLoadedAction]);Multiple types
You can provide multiple types, just like in the ofType(...) pipe.
booksLoaded$ = observe([booksLoadedAction, booksLoadFailedAction]);Custom mapper
The observe(...) function has an additional parameter to provide a custom customMapper mapping function.
Initially this will be:
action => actionTo use a custom mapper, provide it as second argument in the observe(...) function.
export const toData = action => action.data;
...
dataLoaded$ = observe([dataLoadedAction], toData);Deprecated Annotations
Before Version 12 the Store Service used annotations instead of functions. This old way still works but is deprecated and will be removed in the future.
import { Select, StoreService, Dispatch, Selector, Dispatcher, Observe } from '@ngxp/store-service';
@Select(getBooks)
getAllBooks: Selector<typeof getBooks>;
@Dispatch(addBookAction)
addBook: Dispatcher<typeof addBookAction>;
@Observe([dataLoadedAction], toData)
dataLoaded$: Observable<Book[]>;Testing
Testing your components and the StoreService is easy. The @ngxp/store-service/testing package provides useful test-helpers to reduce testing friction.
Testing Components
Testing Selectors
To test selectors you provide the StoreService using the provideStoreServiceMock method in the testing module of your component. Then get the StoreServiceMock<T> instance using the getStoreServiceMock helper function.
import { provideStoreServiceMock, StoreServiceMock, getStoreServiceMock } from '@ngxp/store-service/testing';
...
let bookStoreService: StoreServiceMock<BookStoreService>;
...
TestBed.configureTestingModule({
declarations: [
BookListComponent
],
providers: [
provideStoreServiceMock(BookStoreService)
]
})
...
bookStoreService = getStoreServiceMock(BookStoreService);The StoreServiceMock class replaces all selector functions on the store service class with a BehaviorSubject. So now you can do the following to emit new values to the observables:
bookStoreService.getAllBooks().next(newBooks);The BehaviorSubject is initialized with the value being undefined. If you want a custom initial value, the provideStoreServiceMock method offers an optional parameter. This is an object of key value pairs where the key is the name of the selector function, e.g. getAllBooks.
import { provideStoreServiceMock, StoreServiceMock, getStoreServiceMock } from '@ngxp/store-service/testing';
...
let bookStoreService: StoreServiceMock<BookStoreService>;
...
TestBed.configureTestingModule({
declarations: [
BookListComponent
],
providers: [
provideStoreServiceMock(BookStoreService, {
getAllBooks: []
})
]
})
...
bookStoreService = getStoreServiceMock(BookStoreService);The BehaviorSubject for getAllBooks is now initialized with an empty array instead of undefined.
Testing Actions
To test if a component calls the dispatch methods you provide the StoreService using the provideStoreServiceMock method in the testing module of your component. Then get the StoreServiceMock<T> instance using the getStoreServiceMock helper function.
You can then spy on the method as usual.
import { provideStoreServiceMock, StoreServiceMock } from '@ngxp/store-service/testing';
...
let bookStoreService: StoreServiceMock<BookStoreService>;
...
TestBed.configureTestingModule({
declarations: [
NewBookComponent
]
imports: [
provideStoreServiceMock(BookStoreService)
]
})
...
it('adds a new book', () => {
const book: Book = getBook();
const addBookSpy = jest.spyOn(bookStoreService, 'addBook');
component.book = book;
component.addBook();
expect(addBookSpy).toHaveBeenCalledWith({ book });
});Testing Observers
To test observers inside components you provide the StoreService using the provideStoreServiceMock method in the testing module of your component. Then get the StoreServiceMock<T> instance using the getStoreServiceMock helper function.
import { provideStoreServiceMock, StoreServiceMock, getStoreServiceMock } from '@ngxp/store-service/testing';
...
let bookStoreService: StoreServiceMock<BookStoreService>;
...
TestBed.configureTestingModule({
declarations: [
BookListComponent
],
providers: [
provideStoreServiceMock(BookStoreService)
]
})
...
bookStoreService = getStoreServiceMock(BookStoreService);The StoreServiceMock class replaces all observer properties on the store service class with a BehaviorSubject. So now you can do the following to emit new values to the subscribers:
bookStoreService.booksLoaded$().next(true);The BehaviorSubject is initialized with the value being undefined. If you want a custom initial value, the provideStoreServiceMock method offers an optional parameter. This is an object of key value pairs where the key is the name of the observer property, e.g. booksLoaded$.
import { provideStoreServiceMock, StoreServiceMock, getStoreServiceMock } from '@ngxp/store-service/testing';
...
let bookStoreService: StoreServiceMock<BookStoreService>;
...
TestBed.configureTestingModule({
declarations: [
BookListComponent
],
providers: [
provideStoreServiceMock(BookStoreService, {
booksLoaded$: false
})
]
})
...
bookStoreService = getStoreServiceMock(BookStoreService);The BehaviorSubject for booksLoaded$ is now initialized with false instead of undefined.
Testing StoreService
To test the StoreService itself you use the provided test helpers from @ngrx/store/testing and @ngrx/effects/testing.
Testing StoreService Selectors
You can provide mocks for selectors with the provideMockStore from @ngrx/store/testing a. See (@ngrx/store Testing)[https://ngrx.io/guide/store/testing] for their documentation.
Mock the selectors using the provideMockStore function and check if the StoreService returns an Observable with the mocked value.
import { MockStore, provideMockStore, getStoreServiceMock } from '@ngrx/store/testing';
import { BookStoreService } from 'src/app/shared/books/book-store.service';
import { selectBook, selectBooks } from '../../store/books/books.selectors';
describe('BookStoreService', () => {
let bookStoreService: BookStoreService;
let mockStore: MockStore<{ books: BookState }>;
const books: Book[] = [
{
author: 'Joost',
title: 'Testing the StoreService',
year: 2019
}
];
beforeEach(waitForAsync(() => {
TestBed.configureTestingModule({
providers: [
BookStoreService,
provideMockStore({
selectors: [
{
selector: selectBooks,
value: books
},
{
selector: selectBook,
value: books[0]
}
]
})
]
});
}));
beforeEach(() => {
bookStoreService = getStoreServiceMock(BookStoreService);
mockStore = TestBed.inject(Mockstore);
});
it('executes the getBooks Selector', () => {
const expected = cold('a', { a: books });
expect(bookStoreService.getAllBooks()).toBeObservable(expected);
});
it('executes the getBook Selector', () => {
const expected = cold('a', { a: books[0] });
expect(bookStoreService.getBook({ id: 0 })).toBeObservable(expected);
});
});Testing StoreService Actions
You can provide mocks for selectors with the provideMockStore from @ngrx/store/testing a. See (@ngrx/store Testing)[https://ngrx.io/guide/store/testing] for their documentation.
Mock the selectors using the provideMockStore function and check if the StoreService returns an Observable with the mocked value.
To test if the StoreService dispatches the correct actions the MockStore from @ngrx has a property called scannedActions$. This is an Observable of all dispatched actions to check if an action was dispatched correctly.
import { MockStore, provideMockStore, getStoreServiceMock } from '@ngrx/store/testing';
import { cold } from 'jest-marbles';
import { BookStoreService } from 'src/app/shared/books/book-store.service';
import { addBookAction, loadBooksAction } from '../../store/books/books.actions';
describe('BookStoreService', () => {
let bookStoreService: BookStoreService;
let mockStore: MockStore<{ books: BookState }>;
beforeEach(waitForAsync(() => {
TestBed.configureTestingModule({
providers: [
BookStoreService,
provideMockStore()
]
});
}));
beforeEach(() => {
bookStoreService = getStoreServiceMock(BookStoreService);
mockStore = TestBed.inject(MockStore);
});
it('dispatches a new addBookAction', () => {
const book: Book = getBook();
bookStoreService.addBook({ book });
const expected = cold('a', { a: addBookAction({ book }) });
expect(mockStore.scannedActions$).toBeObservable(expected);
});
it('dispatches a new loadBooksAction', () => {
bookStoreService.loadBooks();
const expected = cold('a', { a: loadBooksAction() });
expect(mockStore.scannedActions$).toBeObservable(expected);
});
});Testing StoreService Observers
To test the observers / actions stream, you import the provideMockActions from @ngrx/effects/testing inside the testing module.
Then check if the Observer filters the correct actions.
import { getStoreServiceMock } from '@ngxp/store-service/testing';
import { provideMockActions } from '@ngrx/effects/testing';
import { BehaviorSubject } from 'rxjs';
import { BookStoreService } from 'src/app/shared/books/book-store.service';
import { booksLoadedAction } from '../../store/books/books.actions';
describe('BookStoreService', () => {
let bookStoreService: BookStoreService;
const mockActions = new BehaviorSubject(undefined);
beforeEach(waitForAsync(() => {
TestBed.configureTestingModule({
providers: [
BookStoreService,
provideMockActions(mockActions)
]
});
}));
beforeEach(() => {
bookStoreService = getStoreServiceMock(BookStoreService);
});
it('filters the BooksLoadedActions in booksLoaded$', () => {
const expectedValue: Book[] = [{
author: 'Author',
title: 'Title',
year: 2018
}];
const action = booksLoadedAction({ books: expectedValue });
mockActions.next(action);
const expected = cold('a', { a: action });
expect(bookStoreService.booksLoaded$()).toBeObservable(expected);
});
});Examples
For detailed examples of all this have a look at the Angular Project in the apps/store-service-sample folder.
Example Store Service
Have a look at the BookStoreService
Example Tests
For examples on Component Tests please have look at the test for the BookListComponent and the NewBookComponent
Testing the StoreService is also very easy. For an example have a look at the BookStoreService