Introduction

NGXS Persistence API is an extension based the Repository Design Pattern that offers a gentle introduction to NGXS by simplifying management of entities or plain data while reducing the amount of explicitness.

Key Concepts

The main purpose of this extension is to provide the necessary layer of abstraction for states. Automates the creation of actions, dispatchers, and selectors for each entity type.

Benefits:

• Angular-way (State as a Service)
• Snapshot's from state out-of-the-box (@Computed())
• Support debounce for throttling dispatch (@Debounce())
• Simple manipulation with data from states (NgxsDataRepository<T>)
• Automatic type inference from selection data stream (myState.state$)
• Immutable state context out-of-the-box (NgxsImmutableDataRepository<T>)
• Entity adapter out-of-the-box (NgxsDataEntityCollectionsRepository<V, K>)
• Simple API for testing states (ngxsTestingPlatform([A], (store: Store, a: A) => {...}))
• Persistence state out-of-the-box in sessionStorage, localStorage, custom (@Persistence())
• Automatic action naming by service methods for improved debugging (@DataAction(), @Payload(), @Named())

Minimal peer dependencies:

• Require minimal @ngxs/store v3.6.2
• Require minimal TypeScript v3.7.2

If you are using Angular 8, you can write in the tsconfig.json:

{
    "angularCompilerOptions": {
        "disableTypeScriptVersionCheck": true
    },
    "compilerOptions": {}
}

Browsers support

| IE / Edge | Firefox | Chrome | Safari | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | Edge 12+ (IE + polyfills) | Firefox 42+ | Chrome 42+ | Safari 10+ |

Quick Links

• ✨ Learn about it on the docs
• 🚀 See it in action on Stackblitz
• 😎 Checkout the sample application
• 📝 Learn about updates from the changelog

Simple example

Before

counter.state.ts

import { State, Action, StateContext } from '@ngxs/store';

export class Increment {
    static readonly type = '[Counter] Increment';
}

export class Decrement {
    static readonly type = '[Counter] Decrement';
}

@State<number>({
    name: 'counter',
    defaults: 0
})
export class CounterState {
    @Action(Increment)
    increment(ctx: StateContext<number>) {
        ctx.setState(ctx.getState() + 1);
    }

    @Action(Decrement)
    decrement(ctx: StateContext<number>) {
        ctx.setState(ctx.getState() - 1);
    }
}

app.component.ts

import { Component } from '@angular/core';
import { Select, Store } from '@ngxs/store';

import { CounterState, Increment, Decrement } from './counter.state';

@Component({
    selector: 'app-root',
    template: `
        <ng-container *ngIf="counter$ | async as counter">
            <h1>{{ counter }}</h1>
        </ng-container>

        <button (click)="increment()">Increment</button>
        <button (click)="decrement()">Decrement</button>
    `
})
export class AppComponent {
    @Select(CounterState) counter$: Observable<number>;
    constructor(private store: Store) {}

    increment() {
        this.store.dispatch(new Increment());
    }

    decrement() {
        this.store.dispatch(new Decrement());
    }
}

After

counter.state.ts

import { State } from '@ngxs/store';
import { action, StateRepository } from '@ngxs-labs/data/decorators';
import { NgxsDataRepository } from '@ngxs-labs/data/repositories';

@StateRepository()
@State<number>({
    name: 'counter',
    defaults: 0
})
@Injectable()
export class CounterState extends NgxsDataRepository<number> {
    @DataAction() increment() {
        this.ctx.setState((state) => ++state);
    }

    @DataAction() decrement() {
        this.ctx.setState((state) => --state);
    }
}

app.component.ts

import { Component } from '@angular/core';

import { CounterState } from './counter.state';

@Component({
    selector: 'app-root',
    template: `
        <h1>{{ counter.snapshot }}</h1>
        <button (click)="counter.increment()">Increment</button>
        <button (click)="counter.decrement()">Decrement</button>
    `
})
export class AppComponent {
    constructor(counter: CounterState) {}
}