e-book

view-purchase-contract.component.ts

export class ViewPurchaseContractComponent implements OnInit, OnDestroy {

  selectedPurchaseContract$: Observable<PurchaseContractModel>;
  image$: Observable<Blob>;

  constructor(
    private store$: Store<fromStore.AppState>,
  ) { }

  ngOnInit() {

    this.selectedPurchaseContract$ = this.store$.pipe(
      select(fromStore.getSelectedProductWidget),
      filter(product => !!product),
      tap(product => 
        this.store$.dispatch(PurchaseContractActions.
          loadPurchaseContract({ address: product.contractAddress }))),
      // we switch from one observable to another
      switchMap(() => 
         this.store$.select(fromStore.getSelectedPurchaseContract)),
      filter(contract => !!contract),
    );

    this.image$ = this.store$.pipe(
      select(fromStore.getSelectedPurchaseContract),
      filter(contract => !!contract),
      tap(contract =>
        this.store$.dispatch(IpfsImageActions.
          downloadImage({ ipfsHash: contract.ipfsHash }))
      ),
      // we switch from one observable to another
      switchMap(() => this.store$.select(fromStore.getImageBlob)),
      filter(image => !!image)
    );
  }