如何让我的 Hapi 路由在返回值之前等待数据？

Question

我正在使用 Hapi.js 并且有一个我想用来获取数据然后返回结果的路由。

我曾尝试使用 async/await，但我一定做错了，因为当我调用的函数最终将结果打印到控制台时，路由正在返回，而无需等待该函数返回值。

'use strict';

const Hapi = require('@hapi/hapi');
const HandyStorage = require('handy-storage');
var ethBalance ='';

// Connection to public blockchain via Infura.io
const Web3 = require("web3");
const web3 = new Web3(new Web3.providers.HttpProvider("https://mainnet.infura.io/v3/cf44bc52af3743bcad5f0b66813f8740"));

// Initialize Handy Storage
const storage = new HandyStorage({
    beautify: true
});

//Get ETH address from Handy Storage
storage.connect('./preferences.json');
var walletAddress = storage.state.wallet;

// Get wallet balance
const getWalletBalance = async () => {

    web3.eth.getBalance(`${walletAddress}`, async function(err, result) {
        if (err) {
        console.log('There was an error: ' + err);
        return ({ error: 'The wallet balance call failed.' });
        } else {
            ethBalance = await web3.utils.fromWei(result, "ether");
            console.log("This should be first: The wallet balance via API call is " + ethBalance + " ETH.");
            return ethBalance; // I expect the walletbalance route to wait for this to be returned
        }
    });
};

// API Server
const init = async () => {

    // Connection settings
    const server = Hapi.server({
        port: 3000,
        host: 'localhost'
    });

    // Get wallet balance
    server.route({
        method: 'GET',
        path: '/walletbalance/',
        handler: async (request, h) => {
            let result = null;
            try {
                result = await getWalletBalance();
                console.log('This should be second, after the getWalletBalance function has printed to the console.'); // this prints first, so await isn't working as expected
                return ({ ethBalance: result });
            } catch (err) {
                console.log('Error in walletbalance route');
            }
        }
    });

    // 404 error handling
    server.route({
        method: '*',
        path: '/{any*}',
        handler: function (request, h) {

            return ({
                message: 'Error!'
            });
        }
    });

    await server.start();
    console.log('Server running on %s', server.info.uri);
};

process.on('unhandledRejection', (err) => {
    console.log(err);
    process.exit(1);
});

init();

知道我在哪里出错了吗？这是我第一次使用 async/await。

ETA：我的控制台如下所示：

[nodemon] starting `node index.js`
Server running on http://localhost:3000
This should be second, after the getWalletBalance function has printed to the console.
This should be first: The wallet balance via API call is 4061.894069996147660079 ETH.

这是我使用钱包余额路由时返回的 JSON：

{}

Answer 1

根据我得到的答案，我能够得到我想要的结果：

'use strict';

const Hapi = require('@hapi/hapi');
const HandyStorage = require('handy-storage');
var ethBalance ='';

// Connection to public blockchain via Infura.io
const Web3 = require("web3");
const web3 = new Web3(new Web3.providers.HttpProvider("https://mainnet.infura.io/v3/cf44bc52af3743bcad5f0b66813f8740"));

// Initialize Handy Storage
const storage = new HandyStorage({
    beautify: true
});

//Get ETH address from Handy Storage
storage.connect('./preferences.json');
var walletAddress = storage.state.wallet;

// Get wallet balance
async function getWalletBalance(){
    let ethBalance = await web3.eth.getBalance(`${walletAddress}`);
      if (ethBalance.err) { 
        console.log('error in the called function');
        } else {
        return ethBalance;
  }
}

// API Server
const init = async () => {

    // Connection settings
    const server = Hapi.server({
        port: 3000,
        host: 'localhost'
    });

    // Get wallet balance
    server.route({
        method: 'GET',
        path: '/walletbalance/',
        handler: async (request, h) => {
            try {
                const result = await getWalletBalance();
                const ethBalanceInWei = web3.utils.fromWei(result, "ether");
                return ({ balance: ethBalanceInWei });
            } catch (err) {
                console.log('Error in walletbalance route');
            }
        }
    });

    // 404 error handling
    server.route({
        method: '*',
        path: '/{any*}',
        handler: function (request, h) {

            return ({
                message: 'Error!'
            });
        }
    });

    await server.start();
    console.log('Server running on %s', server.info.uri);
};

process.on('unhandledRejection', (err) => {
    console.log(err);
    process.exit(1);
});

init();

感谢您的帮助！这让我朝着正确的方向前进。

Answer 2

基本上你的getWalletBalance 函数使用了多个概念。回调风格的函数和你正在使用的内部等待。我已经对您的代码进行了一些重组。希望这能解决您面临的问题。

'use strict';

const Hapi = require('@hapi/hapi');
const HandyStorage = require('handy-storage');
var ethBalance ='';

// Connection to public blockchain via Infura.io
const Web3 = require("web3");
const web3 = new Web3(new Web3.providers.HttpProvider("https://mainnet.infura.io/v3/cf44bc52af3743bcad5f0b66813f8740"));

// Initialize Handy Storage
const storage = new HandyStorage({
    beautify: true
});

//Get ETH address from Handy Storage
storage.connect('./preferences.json');
var walletAddress = storage.state.wallet;

function getWalletBalance() {
  return Promise((resolve, reject) => {
    web3.eth.getBalance(`${walletAddress}`, (err, result) => {
      if (err) {
        console.log('There was an error: ' + err);
        reject({ error: 'The wallet balance call failed.' });
        } else {
          resolve(result);
        }
    });
  });
}

// API Server
const init = async () => {

    // Connection settings
    const server = Hapi.server({
        port: 3000,
        host: 'localhost'
    });

    // Get wallet balance
    server.route({
        method: 'GET',
        path: '/walletbalance/',
        handler: async (request, h) => {
            try {
                const result = await getWalletBalance();
                ethBalance = await web3.utils.fromWei(result, "ether");
                return ethBalance;
            } catch (err) {
                console.log('Error in walletbalance route');
            }
        }
    });

    // 404 error handling
    server.route({
        method: '*',
        path: '/{any*}',
        handler: function (request, h) {

            return ({
                message: 'Error!'
            });
        }
    });

    await server.start();
    console.log('Server running on %s', server.info.uri);
};

process.on('unhandledRejection', (err) => {
    console.log(err);
    process.exit(1);
});

init();