Introduction to Google Auth OAuthlib

Google Auth OAuthlib is a Python library that can be used to authenticate users via OAuth 2.0. This powerful toolkit helps developers connect their applications to Google’s APIs with ease. In this guide, we will explore the various APIs provided by this library and demonstrate how you can use them through several code snippets.

Getting Started

First, you’ll need to install the library:

  pip install google-auth google-auth-oauthlib google-auth-httplib2

Authorizing Requests

To authorize requests to Google’s APIs, you will need to obtain OAuth 2.0 credentials and use them to create an authorized session. Below is an example of how you can achieve this:

  import google.oauth2.credentials
  from google_auth_oauthlib.flow import InstalledAppFlow
  from google.auth.transport.requests import Request

  # Use your own credentials.json file
  flow = InstalledAppFlow.from_client_secrets_file(
      'path/to/credentials.json',
      scopes=['https://www.googleapis.com/auth/drive.metadata.readonly']
  )

  credentials = flow.run_local_server(port=0)

  # Save credentials for the next run
  with open('token.json', 'w') as token:
      token.write(credentials.to_json())

Using Authorized Session

Once you have obtained the credentials, you can use them to make authorized requests:

  from google.auth.transport.requests import Request
  import google.auth

  creds = None
  if os.path.exists('token.json'):
      creds = google.oauth2.credentials.Credentials.from_authorized_user_file('token.json')

  if not creds or not creds.valid:
      if creds and creds.expired and creds.refresh_token:
          creds.refresh(Request())
      else:
          # Follow the previous steps to get new credentials
          pass

  service = googleapiclient.discovery.build('drive', 'v3', credentials=creds)

  results = service.files().list(pageSize=10).execute()
  items = results.get('files', [])

  if not items:
      print('No files found.')
  else:
      print('Files:')
      for item in items:
          print(u'{0} ({1})'.format(item['name'], item['id']))

Creating a Simple App

Let’s create a simple command-line application that lists files in your Google Drive:

  import os
  import google.auth
  import googleapiclient.discovery
  from google_auth_oauthlib.flow import InstalledAppFlow

  SCOPES = ['https://www.googleapis.com/auth/drive.metadata.readonly']

  def main():
      creds = None
      if os.path.exists('token.json'):
          creds = google.oauth2.credentials.Credentials.from_authorized_user_file('token.json', SCOPES)

      if not creds or not creds.valid:
          if creds and creds.expired and creds.refresh_token:
              creds.refresh(Request())
          else:
              flow = InstalledAppFlow.from_client_secrets_file('credentials.json', SCOPES)
              creds = flow.run_local_server(port=0)
              with open('token.json', 'w') as token:
                  token.write(creds.to_json())

      service = googleapiclient.discovery.build('drive', 'v3', credentials=creds)

      results = service.files().list(pageSize=10, fields="nextPageToken, files(id, name)").execute()
      items = results.get('files', [])

      if not items:
          print('No files found.')
      else:
          print('Files:')
          for item in items:
              print(u'{0} ({1})'.format(item['name'], item['id']))

  if __name__ == '__main__':
      main()

Conclusion

Google Auth OAuthlib is a versatile tool that allows developers to easily integrate Google’s powerful API offerings into their applications. By following the examples and instructions in this guide, you will be well on your way to creating robust and secure applications that leverage Google’s services.

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