Extending scopes for Google API key

Question

I have an API key for my node js application to access Google spreadsheets. Now I would like to access also Gmail API. So I activated the Gmail API in the cloud console but when I add the scope

'https://www.googleapis.com/auth/gmail' to my google.auth() request I get an error message:

"invalid credentials'.

What else is required to use the Gmail API with that API key?

Because the API key is for the whole project I assumed that it will authorize also newly activated APIs. I created a new key for the API, but it did not help. Do I have to create a new API key?

Answer 1

It seems like you're encountering an issue with authentication when trying to access the Gmail API in your Node.js application using your existing API key. Let's address this problem step by step:

API Key vs. OAuth 2.0: First, it's essential to understand the distinction between API keys and OAuth 2.0 authentication. API keys are primarily used for identifying your project when making API requests, while OAuth 2.0 is used for user authentication and authorization.

OAuth 2.0 for Gmail API: The Gmail API requires OAuth 2.0 authentication because it involves accessing user data (email content). Therefore, you need to obtain OAuth 2.0 credentials (client ID and client secret) to authenticate your application with the Gmail API.

Creating OAuth 2.0 Credentials: To create OAuth 2.0 credentials for your Node.js application to access the Gmail API, follow these steps:

a. Go to the Google Cloud Console: https://console.cloud.google.com/.

b. Select your project.

c. Navigate to the "APIs & Services" > "Credentials" page.

d. Click on "Create credentials" and select "OAuth client ID."

e. Choose "Web application" as the application type.

f. Enter the authorized redirect URIs for your application. For development purposes, you can use http://localhost:PORT/auth/google/callback.

g. After creating the OAuth client ID, you'll receive a client ID and client secret. Save these credentials securely.

Implement OAuth 2.0 in Node.js: In your Node.js application, use a library like google-auth-library to handle OAuth 2.0 authentication. Here's a basic example of how to authenticate with Gmail API using OAuth 2.0 in Node.js:

const { google } = require('googleapis'); const { OAuth2Client } = require('google-auth-library');

const oauth2Client = new OAuth2Client({ clientId: 'YOUR_CLIENT_ID', clientSecret: 'YOUR_CLIENT_SECRET', redirectUri: 'http://localhost:PORT/auth/google/callback', });

// Generate an authentication URL const authUrl = oauth2Client.generateAuthUrl({ access_type: 'offline', scope: 'https://www.googleapis.com/auth/gmail.readonly', // Adjust scope as needed });

// Redirect users to authUrl and handle the callback to obtain access token

// Initialize Gmail API using OAuth2Client const gmail = google.gmail({ version: 'v1', auth: oauth2Client });

// Use Gmail API methods to interact with Gmail

Authorization Error Handling: If you're still encountering "invalid credentials" errors, ensure that you're providing the correct client ID and client secret obtained from the Google Cloud Console. Also, make sure that the authorized redirect URIs match the ones specified in your OAuth 2.0 credentials.

By following these steps and implementing OAuth 2.0 authentication in your Node.js application, you should be able to access the Gmail API successfully. Remember to handle user consent and token management securely in your application.