Error: User credentials required in Google Cloud Print API

To make my first test, I am looking to get all information about my printer.

What I did:

1. I created a project in: https://console.developers.google.com
2. Inside the project created, I created a credential:
   • create credentials -> OAuth client ID

And I chose Application type: Web, and also configure the restrictions to source and redirection to my localhost.

1. Manually in https://www.google.com/cloudprint, I added my printer, I made a test printing a PDF and was OK.
2. I created a project in reactJS to get the information of my printer I've added.

Component:

• I'm using a component react-google-login to obtain easily the user accessToken: https://github.com/anthonyjgrove/react-google-login
• This component only obtains the access token and save it in localStorage, in a variable called googleToken and it draws a button to call a function to obtain the information about the printer.

import React, < Component >from 'react' import GoogleLogin from 'react-google-login'; import < connect >from 'react-redux' import < getPrinters >from '../actions/settings' class Setting extends Component < responseGoogle(response) < const accessToken = response.accessToken localStorage.setItem('googleToken', accessToken) >render() < return ( 
 onFailure= /> < this.props.getPrinters() >> >test printer 
 ) > > const mapStateToProps = state => < return < state: state >> const mapDispatchToProps = dispatch => < return < getPrinters() < dispatch(getPrinters()) >> > export default connect( mapStateToProps, mapDispatchToProps )(Setting) 

Action or Function to get information printer:

• I'm passing the parameter printerid to get information about that printer.
• In authorization, I'm using OAuth . because in the documentation says that(second paragraph).: https://developers.google.com/cloud-print/docs/appInterfaces
• The next two headers I wrote it because I tried solutions as:

import axios from 'axios' axios.defaults.headers.common['Authorization'] = 'OAuth ' + localStorage.getItem('googleToken') axios.defaults.headers.common['scope'] = 'https://www.googleapis.com/auth/cloudprint' axios.defaults.headers.common['X-CloudPrint-Proxy'] = 'printingTest' const getPrinters = () => < return () => < return axios.get('https://www.google.com/cloudprint/printer' , < params: < printeid: 'PRINTER_ID_REMOVED_INTENTIONALLY' >> ) .then(response => < console.log('response of google cloud print') console.log(response) >) > > export

After all explained before, I got the next error:

User credentials required

Error 403

Note:

I'm using CORS plugin by recommendation of:

because initially, I had cors error.

Any suggestion or recommendation would be very useful, thanks.

2 Answers 2

I've resolved my problem, my main problem about User Credential required were because I was using the incorrect access token and It was because I was getting the access token incorrectly.

I'm going to explain my whole solution because there are few examples of codes with this API.

Solutions:

1. The steps described were Ok until the fourth step where I used the external component react-google-login to trying to get the access token, instead I used googleapis module: Link Github googleapis
2. Also to avoid CORS problem(and not use CORS chrome plugin) I wrote the requests to Google API in server side.(NODEJS)
3. I had also a problem in the frontend when I tried to generate a popup to give permission for printer(problems about CORS), my solution was to use this very simple module for authentication: Link Github oauth-open

General scheme:

Knowing I have all data described in my question post(until the third step).

• The next step in getting a URL and use it to the user can authenticate. As I said before I used the module oauth-open in the frontend to generate the popup and only this module need the URL. To get the URL in the backend I used the endpoint /googleurl , where here I used the method generateAuthUrl of the module googleapis to generate the URL.
• After that In the frontend, I got the authentication_code (that returned the module oauth-open ), I send It to my endpoint /googletoken and here I process the authentication_code to generate access token , refresh token and expiration date with the method getToken of the module googleapis . Finally, these data are stored in the database.

• For print, since the frontend, I send what data I need send to the printer. I used my endpoint /print
• In the backend endpoint, my logic was the next:

Recover tokens and expiration date from database, with the expiration date check if the token has expired, and if It has already expired then gets another token and replace the old access token with the new one, replacing also with the new expiration date , to obtain this new data only is necessary call to method refreshAccessToken of module googleapis .Note: the refresh token never expires.

After having the access token updated, use it to send data to the printer with Google route( . /submit )

Code:

• All the next codes are in only 1 file
• Some data as validation, static variables, error handler, etc, has been removed to better understanding.

Route get URL authentication.

const express = require('express'); const google = require('googleapis'); const router = express.Router(); var OAuth2 = google.auth.OAuth2; const redirect_url = 'http://localhost:3001/setting'; //Your redirect URL var oauth2Client = new OAuth2( 'CLIENT ID', //Replace it with your client id 'CLIEND SECRET', //Replace it with your client secret redirect_url ); var url = oauth2Client.generateAuthUrl(< access_type: 'offline', scope: 'https://www.googleapis.com/auth/cloudprint' >); router.get('/googleurl', (req, res) => < return res.status(200).send(< result: < googleURLToken: url >>); >); 

To get tokens using the authentication code and save these in the database.

const Setting = require('../models/setting'); // My model(Mongoose) router.post('/googletoken', (req, res) => < oauth2Client.getToken(req.body.code, function (err, tokens) < oauth2Client.credentials = tokens; // If refresh token exits save it // because the refresh token it returned only 1 time! IMPORTANT if (tokens.hasOwnProperty('refresh_token')) < let setting = new Setting(); setting.refreshTokenGoogle = tokens.refresh_token; setting.expirationTokenGoogle = tokens.expiry_date; setting.tokenGoogle = tokens.access_token; setting.save() .then((settingCreated) =>< return res.status(200).send(< message: 'OK' >); >) > >); >); 

const axios = require('axios'); const moment = require('moment'); router.post('/print',async (req, res) => < const tickeProperties = < 'version': '1.0', 'print': < 'vendor_ticket_item': [], 'color': < 'type': 'STANDARD_MONOCHROME' >, 'copies': < 'copies': 1 >> >; const accessToken = await getTokenGoogleUpdated(); axios.get( 'https://www.google.com/cloudprint/submit', < params: < printerid : printerID, // Replace by your printer ID title: 'title printer', ticket: tickeProperties, content : 'print this text of example. ', contentType: 'text/plain' >, headers: < 'Authorization': 'Bearer ' + accessToken >> ) .then(response => < return res.status(200).send(< result: response.data >); >) > ); async function getTokenGoogleUpdated() < return await Setting.find(<>) .then(async setting => < const refreshTokenGoogle = setting[0].refreshTokenGoogle; const expirationTokenGoogle = setting[0].expirationTokenGoogle; const tokenGoogle = setting[0].tokenGoogle; const dateToday = new Date(); // 1 minute forward to avoid exact time const dateTodayPlus1Minute = moment(dateToday).add(1, 'm').toDate(); const dateExpiration = new Date(expirationTokenGoogle); // Case date expiration, get new token if (dateExpiration < dateTodayPlus1Minute) < console.log('Updating access token'); oauth2Client.credentials['refresh_token'] = refreshTokenGoogle; return await oauth2Client.refreshAccessToken( async function(err, tokens) < // Save new token and new expiration setting[0].expirationTokenGoogle = tokens.expiry_date; setting[0].tokenGoogle = tokens.access_token; await setting[0].save(); return tokens.access_token; >); > else < console.log('Using old access token'); return tokenGoogle; >>) .catch(err => < console.log(err); >); > 

I hope It helps you if you want to use Google Cloud Print to not waste a lot of time as I did.