[英]Backbone Javascript: Wait for a function to finish before running another one
[英]How to wait for function to finish before running another one or rest of the code?
我想不通這個。 我有一個 function 連接到 SFTP 服務器並下載文件。 然后,我有第二個 function 讀取內容,將數據放入數組中,然后返回數組。
問題是第二個 function 總是先運行。 我嘗試了不同的方法,但我無法讓它工作。 與 SFTP 的連接非常慢,可能需要 10 多秒才能完成。 但我需要以某種方式等待它完成,然后再做任何其他事情。
const SFTPConfig = require('../config/keys').sftpconfig;
const getCSATFiles = async function(targetDate) {
try {
let Client = require('ssh2-sftp-client');
let sftp = new Client();
const date = moment(targetDate);
var dir = `../csv/${targetDate}/`;
if (!fs.existsSync(dir)) {
fs.mkdirSync(dir);
}
sftp
.connect(SFTPConfig, 'once')
.then(() => {
return sftp.list('/In/Archives/');
})
.then(data => {
data.forEach(item => {
const fileName = item.name;
const remotePath = '/In/Archives/' + fileName;
const localePath = path.join(dir + fileName);
if (
moment(item.modifyTime)
.format('YYYY-MM-DD hh:mm')
.toString()
.slice(0, 10) ===
date
.format('YYYY-MM-DD hh:mm')
.toString()
.slice(0, 10)
) {
sftp
.fastGet(remotePath, localePath, {})
.then(() => {
console.log('finished getting the files!');
sftp.end();
})
.catch(err => {
sftp.end();
console.log(err, 'fastGet method error');
});
}
});
});
} catch (error) {
console.log(error);
}
};
const readCSVFiles = async function(targetDate) {
try {
const casesBO = [];
var dir = `../csv/${targetDate}/`;
if (!fs.existsSync(dir)) {
fs.mkdirSync(dir);
}
const allLocalFiles = path.join(__dirname, dir);
const readDir = util.promisify(fs.readdir);
const files = await readDir(allLocalFiles);
for (let file of files) {
fs.createReadStream(allLocalFiles + file)
.pipe(csv.parse({ headers: true, delimiter: ';' }))
.on('error', error => console.error(error))
.on('data', row => {
if (row['[REGION2]'] !== 'FR') {
casesBO.push(row['[CALLERNO_EMAIL_SOCIAL]']);
console.log(
`${row['[AGENT]']} is ${row['[REGION2]']} and case = ${
row['[CALLERNO_EMAIL_SOCIAL]']
}`
);
}
})
.on('end', rowCount => {
console.log(`Parsed ${rowCount} rows`);
});
}
return casesBO;
} catch (error) {
console.log(error);
}
};
const testFunc = async () => {
const csatfiles = await getCSATFiles('2021-02-03');
const boData = await readCSVFiles('2021-02-03');
console.log(boData);
};
testFunc();
#1 正如@messerbill 建議的那樣,您需要從 function 中返回 promise。 #2 你的 promise 里面有一個循環,它有更多的承諾。 在這種情況下,您需要收集這些承諾並使用 Promise.all 來解決它們,然后再運行第二次 function。 我在下面需要更改的行上發表了評論。 嘗試這個:
const SFTPConfig = require('../config/keys').sftpconfig;
const getCSATFiles = function(targetDate) {
try {
let Client = require('ssh2-sftp-client');
let sftp = new Client();
const date = moment(targetDate);
var dir = `../csv/${targetDate}/`;
if (!fs.existsSync(dir)) {
fs.mkdirSync(dir);
}
// I return the promise here
return sftp
.connect(SFTPConfig, 'once')
.then(() => {
return sftp.list('/In/Archives/');
})
.then(data => {
// I set up my promises as a blank array
const promises = [];
data.forEach(item => {
const fileName = item.name;
const remotePath = '/In/Archives/' + fileName;
const localePath = path.join(dir + fileName);
if (
moment(item.modifyTime)
.format('YYYY-MM-DD hh:mm')
.toString()
.slice(0, 10) ===
date
.format('YYYY-MM-DD hh:mm')
.toString()
.slice(0, 10)
) {
// I collect the promises here
promises.push(sftp
.fastGet(remotePath, localePath, {})
.then(() => {
console.log('finished getting the files!');
sftp.end();
})
.catch(err => {
sftp.end();
console.log(err, 'fastGet method error');
}));
}
});
// I resolve them here
return Promise.all(promises);
});
} catch (error) {
console.log(error);
}
};
const readCSVFiles = async function(targetDate) {
try {
const casesBO = [];
var dir = `../csv/${targetDate}/`;
if (!fs.existsSync(dir)) {
fs.mkdirSync(dir);
}
const allLocalFiles = path.join(__dirname, dir);
const readDir = util.promisify(fs.readdir);
const files = await readDir(allLocalFiles);
for (let file of files) {
fs.createReadStream(allLocalFiles + file)
.pipe(csv.parse({ headers: true, delimiter: ';' }))
.on('error', error => console.error(error))
.on('data', row => {
if (row['[REGION2]'] !== 'FR') {
casesBO.push(row['[CALLERNO_EMAIL_SOCIAL]']);
console.log(
`${row['[AGENT]']} is ${row['[REGION2]']} and case = ${
row['[CALLERNO_EMAIL_SOCIAL]']
}`
);
}
})
.on('end', rowCount => {
console.log(`Parsed ${rowCount} rows`);
});
}
return casesBO;
} catch (error) {
console.log(error);
}
};
const testFunc = async () => {
const csatfiles = await getCSATFiles('2021-02-03');
const boData = await readCSVFiles('2021-02-03');
console.log(boData);
};
testFunc();
您需要注意,您要在 function 主體內返回要解析的 promise,以便在正確的時間解析 promise。
async function promiseNotReturned() { new Promise(resolve => setTimeout(resolve.bind(null), 5000)) } async function promiseReturned() { return new Promise(resolve => setTimeout(resolve.bind(null), 5000)) } async function run() { await promiseNotReturned() console.log("does not wait for 5 seconds") await promiseReturned() console.log("waits for 5 seconds") } run()
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