node.js - Hyperledger Fabric registerChaincodeEvent() 方法未从链代码获取事件

Question

在成功部署我的链代码并能够从其数据中执行某些操作后(返回的所有数据都是正确的)，我无法检查是否发出了事件。Invoke() 中的函数是 queryAllMachines()，如果我只调用这个函数，它会返回一组机器(在 InitLedger() 方法中插入的一组机器)

我遵循文档，我的链代码(在 go 中)应该在其 queryAllMachines() 函数内的此代码行中发出一个事件:

func (s *testContract) queryAllMachines(APIstub shim.ChaincodeStubInterface) sc.Response {
    fmt.Println("inside queryAllMachines\n")
    ...
    err = APIstub.SetEvent("evtsender", []byte("adadsads"))
    if err != nil {
        return shim.Error("event not set")
    }
    fmt.Printf("No errors\n")
}

此代码始终打印“无错误”，因此我认为事件已正确发出。

然后在我的 .js 文件中查询我有请求:

let request = {
        chaincodeId: 'oraclize-test-integration',
        fcn: 'queryAllMachines',
        args: [''],
        txId: tx_object
    };

然后这是我的 .js 文件中我遇到问题的部分以及我想启动 registerChaincodeEvent() 的部分:

let event_monitor = new Promise((resolve, reject) => {
        let regid = null;
        let handle = setTimeout(() => {
            if (regid) {
                // might need to do the clean up this listener
                channel_event_hub.unregisterChaincodeEvent(regid);
                console.log('Timeout - Failed to receive the chaincode event');
            }
            reject(new Error('Timed out waiting for chaincode event'));
        }, 20000);

        regid = channel_event_hub.registerChaincodeEvent('oraclize-test-integration', 'evtsender',
            (event, block_num, txnid, status) => {
                // This callback will be called when there is a chaincode event name
                // within a block that will match on the second parameter in the registration
                // from the chaincode with the ID of the first parameter.
                console.log('Successfully got a chaincode event with transid:' + txnid + ' with status:' + status);

                // might be good to store the block number to be able to resume if offline
                storeBlockNumForLater(block_num);

                // to see the event payload, the channel_event_hub must be connected(true)
                let event_payload = event.payload.toString('utf8');
                if (event_payload.indexOf('CHAINCODE') > -1) {
                    clearTimeout(handle);
                    // Chaincode event listeners are meant to run continuously
                    // Therefore the default to automatically unregister is false
                    // So in this case we want to shutdown the event listener once
                    // we see the event with the correct payload
                    channel_event_hub.unregisterChaincodeEvent(regid);
                    console.log('Successfully received the chaincode event on block number ' + block_num);
                    resolve('RECEIVED');
                } else {
                    console.log('Successfully got chaincode event ... just not the one we are looking for on block number ' + block_num);
                }
            }, (error) => {
                clearTimeout(handle);
                console.log('Failed to receive the chaincode event ::' + error);
                reject(error);
            }
            // no options specified
            // startBlock will default to latest
            // endBlock will default to MAX
            // unregister will default to false
            // disconnect will default to false
        );
    });

    // build the promise to send the proposals to the orderer
    let send_trans = channel.sendTransaction({
        proposalResponses: query_responses[0],
        proposal: query_responses[1]
    });

    // now that we have two promises all set to go... execute them
    return Promise.all([event_monitor, send_trans]);

出现的错误是:

Timeout - Failed to receive the chaincode event (node:9180) UnhandledPromiseRejectionWarning: Unhandled promise rejection (rejection id: 3): Error: Timed out waiting for chaincode event (node:9180) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with anon-zero exit code.

因此函数在这部分代码中超时，即使我启动另一个成功执行调用 queryAllMachines() 函数的 .js 文件也是如此:

let handle = setTimeout(() => {
            if (regid) {
                // might need to do the clean up this listener
                channel_event_hub.unregisterChaincodeEvent(regid);
                console.log('Timeout - Failed to receive the chaincode event');
            }
            reject(new Error('Timed out waiting for chaincode event'));
        }, 20000);

Answer 1

最新的高级 API 使它变得简单，

        const listener = await contract.addContractListener('asset creation-listener', 'saveAsset123456789', (err, event, blockNumber, transactionId, status) => {
            if (err) {
                console.error(err);
                return;
            }
            console.log(`The event payload is :${event.payload}`)
            console.log(`Block Number: ${blockNumber} Transaction ID: ${transactionId} Status: ${status}`);
        })

查看 this 文档以获取更多信息