@jeiraon/state-holder

State Holder

state holder is a "mini store like" using RxJs

Install

npm install @jeiraon/state-holder

rxjs is set as a peerDependencies to avoid conflict with your main project. In most use case, you should already have it installed so it will use the same version. Otherwise, you can install it.

npm install rxjs@^6.6.0

Configuration

You can turn on the action logs by using

stateHolderConfig.logger = false; // default false
stateHolderConfig.allowDistinctToPass = false; // default false
stateHolderConfig.allowNullableToPass = false; // default false

Each time an action is dispatched, you will be able to see the logs in your browser's console in the following form { action, state }

Example

Basic

Creating a new basic state holder

// structure of the state
interface SampleState {
    text: string;
}
// init state (when instantiating the class)
const initSampleState: SampleState = {
    text: '',
}
// create an action
const setTextAction = createAction(
        'Set text',
        (state: SampleState, { text }: { text: string }): SampleState => ({ ...state, text })
);
// create a selector
const textSelector = createSelector((state: SampleState): string => state.text);
// instiate a new basic state holder
const state = createBasicState(initSampleState);
// dispatch and select example
state.dispatch(setTextAction, { text: 'sample' });
state.select$(textSelector).subscribe({next: (v) => console.log(v)})

Using the state holder anywhere you need to change or select a specific state

// dispatch and select example
state.dispatch(setTextAction, { text: 'sample' });
state.select$(textSelector).subscribe({next: (v) => console.log(v)})

Using angular Service for more complexe behaviours

// structure of the state
interface ProductState {
    products: string[];
}
// init state (when instantiating the class)
const initProductState: ProductState = {
    products: [],
};
// create an action
const addProductAction = createAction(
        'Add product',
        (state: ProductState, { product }: { product: string }): ProductState => ({
            ...state,
            products: [
                ...state.products,
                product
            ]
        })
);
// create a selector
const productSelector = createSelector((state: ProductState): string[] => state.products);

In a service

@Injectable({
  providedIn: 'root',
})
class ProductService extends StateHolder<ProductState> {
    constructor(http: HttpClient){
        super(initProductState);
    }

    public getProductById(id: string): void {
        this.http.get<string>(`localhost:3000/product/${id}`)
            .pipe(take(1))
            .subscribe((product:string) => {
                this.dispatch(addProductAction, { product });
            })
    }
}

In a component

@Component({
  templateUrl: './product-list.component.html',
  styleUrls: ['./product-list.component.scss']
})
export class ProductListComponent implements OnInit {
    // use `async` pipe in html to subscribe to it and use the data
    public products$: Observable<string[]> = this.productService.select$(productSelector);

    constructor(public productService: ProductService) {}

    ngOnInit(): void {}
}

Parameterized Selector

// Primitive (number, string)
const selectSample = createSelector((state: SampleState, id: number) => state.samples[id]);
state.select$(selectSample, 0).subscribe({ next: s => console.log(s) });

// Array
const selectSamples = createSelector((state: SampleState, ids: number[]) => {
    const samples = [];
    for (const id of ids) {
        samples.push(state.samples[id]);
    }
    return samples;
});

state.select$(selectSamples, [0, 2]).subscribe({ next: s => console.log(s)});

// Object
const selectSamples = createSelector((state: SampleState, { id, key }: { id: number, key: string }) => {
    return {
        id: state.samples[id],
        key: state.dict[key]
    };
});

state.select$(selectSamples, { id: 0, key: 'first' }).subscribe({next: s => console.log(s)});

Dependency

rxjs: ^6.6.0

Note

I like to extend my Angular services with the state-holder when I do need a big Store like NgRx in my app.

CommonJS is not supported., This module has been build for ESNext

Todo

• [x] : Basic implementation
• [x] : Arguments to selector (eg: to get by id)
• [ ] : Add utilitaries functions to help when selecting or disptaching actions
• [ ] : ...