e-book

purchase-contract-service.ts

public confirmPurchase(contractAddress: string, 
                etherValue: string): Observable<string> {

const contract: Contract = 
  new ethers.Contract(contractAddress, this.abi, 
                        this.provider.getSigner());
const wei = utils.parseEther(etherValue);

const token = contract.buyerPurchase({
  value: wei
});

return from(token)
  .pipe(
    switchMap((tx: any) => {

      console.log('buyerConfirmPurchase Tx:', tx);
      // Wait for transaction to be mined
      // Returned a Promise which would resolve to 
      // the TransactionReceipt once it is mined.
      return from(tx.wait()).pipe(
        tap((txReceipt: any) => console.log('txReceipt: ', txReceipt)),

        // The receipt will have an "events" Array, which will have
        // the emitted event from the Contract. The "LogPurchaseConfirmed"
        // call is the last event.
        map(txReceipt => txReceipt.events.pop()),
        tap(txEvent => console.log('event: ', txEvent.event)),
        mapTo(contractAddress),

      );
    }));
  }