Ожидаемые данные возвращаются асинхронно, поэтому вам нужно будет обрабатывать их асинхронно, используя callbacks или async await.
Вот пример использования обратных вызовов.
const express = require('express')
const app = express()
const fs = require('fs')
const readline = require('readline')
const {google} = require('googleapis')
app.get('/', function(req, res) {
res.setHeader('Content-Type', 'application/json')
// let data = getLabels()
getLabels((labels) => {
console.log(labels)
res.json(labels)
})
//console.log('data: ' + data)
//res.json(data)
})
app.get('/hello', function (req, res) {
res.send('hello there')
})
app.listen(3001, () => console.log('server up on 3001'))
const SCOPES = ['https://mail.google.com/',
'https://www.googleapis.com/auth/gmail.modify',
'https://www.googleapis.com/auth/gmail.compose',
'https://www.googleapis.com/auth/gmail.send'
];
const TOKEN_PATH = 'credentials.json';
function getLabels(callback) {
fs.readFile('client_secret.json', (err, content) => {
if (err) return console.log('Error loading client secret file:', err);
// so here, instead of passing it listLabels directly, we will pass it just a regular callback, and call listlabels inside that callback. This way we can choose what to do with listlabels return value.
authorize(JSON.parse(content), (auth) => {
listLabels(auth, (listOfLabels) => {
console.log(listOfLabels) // we should have the list here
callback(listOfLabels)
}) //match the original arguments
});
});
}
function authorize(credentials, callback) {
const {client_secret, client_id, redirect_uris} = credentials.installed;
const oAuth2Client = new google.auth.OAuth2(
client_id, client_secret, redirect_uris[0]);
// Check if we have previously stored a token.
fs.readFile(TOKEN_PATH, (err, token) => {
if (err) return getNewToken(oAuth2Client, callback);
oAuth2Client.setCredentials(JSON.parse(token));
callback(oAuth2Client);
});
}
function getNewToken(oAuth2Client, callback) {
const authUrl = oAuth2Client.generateAuthUrl({
access_type: 'offline',
scope: SCOPES,
});
console.log('Authorize this app by visiting this url:', authUrl);
fs.writeFile('getCredentials.txt', authUrl, (err) => {
if (err) throw err;
console.log('getCredentials.txt saved!')
})
const rl = readline.createInterface({
input: process.stdin,
output: process.stdout,
});
rl.question('Enter the code from that page here: ', (code) => {
rl.close();
oAuth2Client.getToken(code, (err, token) => {
if (err) return callback(err);
oAuth2Client.setCredentials(token);
// Store the token to disk for later program executions
fs.writeFile(TOKEN_PATH, JSON.stringify(token), (err) => {
if (err) return console.error(err);
console.log('Token stored to', TOKEN_PATH);
});
callback(oAuth2Client);
});
});
}
function listLabels(auth, callback) {
const gmail = google.gmail({version: 'v1', auth});
console.log('here')
gmail.users.messages.list({
userId: 'me',
maxResults: 10
}, (err, {data}) => {
if (err) return console.log('The API returned an error: ' + err);
console.log('data in listlabels ' + JSON.stringify(data))
//return data
let dataForExpress
let messages = data.messages
messages.forEach(function (message, index) {
console.log("Inside foreach, message and index :", message, index)
gmail.users.messages.get({
userId: 'me',
id: message.id,
format: 'raw'
}, (err, {data}) => {
if (err) return console.log('Error: ' + err)
console.log(data)
dataForExpress.push(data)
if dataForExpress.length == messages.length { // we done
callback(dataForExpress)
}
});
})
})
}