Lesson 14 :How to get requestId from requestNft function in randomIpfsNft.test.js

[BhaveshJoshi2000]

In the Repo following code is used to get requestId in lesson-14:

try {
          const fee = await randomIpfsNft.getMintFee()

          const tx = await randomIpfsNft.requestNft({ value: fee })
          const txReceipt = await tx.wait(1)

          console.log(txReceipt)

          await vrfCoordinator.fulfillRandomWords(
                     txReceipt.events[1].args.requestId,
                     randomIpfsNft.address
                   )
     } catch (e) {
           console.log(e)
           reject(e)
     }

I am confused why
txReceipt.events[1].args.requestId,
is written instead of
txReceipt.events[0].args.requestId,

A Help would be really appreciated.

[0xpolarzero]

You can do console.log(txReceipt.events) to make it more transparent. The object in which the requestId is returned is the second one (index 1), not the first one (index 0).

I would be curious to know what lies in that first object tho. It seems like it's actually the logs from requesting the tx receipt? I honestly have no idea.

[BhaveshJoshi2000]

@polar0 the first object is of event emitted by requestRandomWords from VRFCoordinatorV2Mock
But that event also have requestId as args, but any of the args passed in that event is not showing in the first object.
I wonder why

[alymurtazamemon]

@BhaveshJoshi2000 As @polar0 shown above, there are two events, one that we are emitting and one that is requestRandomWords function is generating and that one emits before our event. That is the reason we are accessing the event at index 1 because the event generated by requestRandomWords is at index 0.

[BhaveshJoshi2000]

Thanks @alymurtazamemon, but when i checked requestRandomWords in VRFCOordinatorV2Mock ,is also emits the event which has requestId as args.

function requestRandomWords(
    bytes32 _keyHash,
    uint64 _subId,
    uint16 _minimumRequestConfirmations,
    uint32 _callbackGasLimit,
    uint32 _numWords
  ) external override onlyValidConsumer(_subId, msg.sender) returns (uint256) {
    if (s_subscriptions[_subId].owner == address(0)) {
      revert InvalidSubscription();
    }

    uint256 requestId = s_nextRequestId++;
    uint256 preSeed = s_nextPreSeed++;

    s_requests[requestId] = Request({subId: _subId, callbackGasLimit: _callbackGasLimit, numWords: _numWords});

    emit RandomWordsRequested(
      _keyHash,
      requestId,
      preSeed,
      _subId,
      _minimumRequestConfirmations,
      _callbackGasLimit,
      _numWords,
      msg.sender
    );
    return requestId;
  }

but any args which is passed in first event is not there in first events object.
What might be the reason?

[alymurtazamemon]

@BhaveshJoshi2000 I am not sure about it, because we do not care about it. We only need requested from our event.