Google Api与Google Auth Library选型：OAuth2认证该用哪一个？

Let me break down the differences clearly and help you pick the right tool for your OAuth2 flow:

Core Purpose & Scope #

• Google Auth Library: This is a foundational, authentication-focused library. It handles all the heavy lifting for identity verification—think generating OAuth2 tokens, managing refresh tokens, validating ID tokens, and working with service account keys. It doesn't directly interact with specific Google APIs (like Drive or Gmail); its sole job is to make sure your requests are properly authenticated.
• Google API Client: This is a higher-level library that wraps around individual Google APIs (e.g., YouTube Data API, Calendar API). It relies on the Google Auth Library under the hood for authentication, but its main goal is to simplify calling actual API endpoints with pre-built methods and structured requests.

Which to Use for Google OAuth2 Authentication? #

• If your only need is to handle the OAuth2 flow itself (like getting an authorization code, exchanging it for access/refresh tokens, or refreshing expired tokens), go straight with the Google Auth Library. It's lightweight and focused exactly on this task.
• If you plan to use the authenticated credentials to call specific Google APIs (e.g., list files in a user's Drive, send emails via Gmail), use the Google API Client. It integrates seamlessly with the Auth Library, so you can handle authentication and API calls in one unified workflow.

Explaining the setCredentials() vs Credentials Property Difference #

Your observation about the two GitHub repos makes total sense given their designs:

• Google API Client (google-api-nodejs-client): The service-specific instances (like google.drive() or google.gmail()) provide the setCredentials() method as a convenience. This lets you attach credentials directly to the API client, so every subsequent API call you make with that instance automatically uses those credentials. Example:

  const { google } = require('googleapis');
  const calendar = google.calendar({ version: 'v3' });
  // Set credentials for all Calendar API calls
  calendar.setCredentials({ access_token: 'YOUR_ACCESS_TOKEN' });
  // Now call API endpoints without re-specifying credentials
  const events = await calendar.events.list({ calendarId: 'primary' });
  

• Google Auth Library (google-auth-library-nodejs): The core authentication objects (like OAuth2Client) store credentials directly in the credentials property. While it does have a setCredentials() helper method, you can also directly assign to the property if you prefer. Example:

  const { OAuth2Client } = require('google-auth-library');
  const oAuth2Client = new OAuth2Client(CLIENT_ID, CLIENT_SECRET, REDIRECT_URI);
  
  // Option 1: Use the helper method
  oAuth2Client.setCredentials({ access_token: 'YOUR_TOKEN', refresh_token: 'YOUR_REFRESH_TOKEN' });
  
  // Option 2: Directly assign the property
  oAuth2Client.credentials = { access_token: 'YOUR_TOKEN', refresh_token: 'YOUR_REFRESH_TOKEN' };
  

The difference here is just a design choice tailored to each library's use case—one simplifies API call workflows, the other gives you direct control over the authentication layer.

内容的提问来源于stack exchange，提问作者rabashani