(Ruby) Google Calendar -- Refresh an Expired Access Token

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Demonstrates how to refresh an expired access token. If a Google Calendar REST API call results in a 401 "unauthorized" response, then it is likely the access token expired. An application should be able to automatically refresh the access token with no user interaction and then re-try the request with the newly obtained access token.

Chilkat Ruby Downloads install from rubygems.org gem install chilkat or download... Ruby Library for Windows, MacOS, Linux, Alpine Linux

require 'chilkat'

# This example requires the Chilkat API to have been previously unlocked.
# See Global Unlock Sample for sample code.

# It is assumed we previously obtained an OAuth2 access token.
# This example loads the JSON access token file 
# saved by this example: Get Google Calendar OAuth2 Access Token

jsonToken = Chilkat::CkJsonObject.new()
success = jsonToken.LoadFile("qa_data/tokens/googleCalendar.json")
if (success != true)
    print "Failed to load googleCalendar.json" + "\n";
    exit
end

# The access token JSON looks like this:

# 	{ 
# 	 "access_token": "abac.Ci-ZabcdF37-NUrmSzxbHxTsMbtlN-uPfabcdAQN_2ekzj0s5ofCzRabcdTDMGaa2Q",
# 	 "token_type": "Bearer",
# 	 "expires_in": 3600,
# 	 "refresh_token": "1/lEe5abcdNJ77eOSDBabcdkQGVmDalkwabcdR2Hatbo"
# 	}
# 

oauth2 = Chilkat::CkOAuth2.new()

oauth2.put_TokenEndpoint("https://www.googleapis.com/oauth2/v4/token")

# Replace these with actual values.
oauth2.put_ClientId("GOOGLE-CLIENT-ID")
oauth2.put_ClientSecret("GOOGLE-CLIENT-SECRET")

# Get the "refresh_token"
oauth2.put_RefreshToken(jsonToken.stringOf("refresh_token"))

# Send the HTTP POST to refresh the access token..
success = oauth2.RefreshAccessToken()
if (success != true)
    print oauth2.lastErrorText() + "\n";
    exit
end

# The response contains a new access token, but we must keep
# our existing refresh token for when we need to refresh again in the future.
jsonToken.UpdateString("access_token",oauth2.accessToken())

# Save the new JSON access token response to a file.
sbJson = Chilkat::CkStringBuilder.new()
jsonToken.put_EmitCompact(false)
jsonToken.EmitSb(sbJson)
sbJson.WriteFile("qa_data/tokens/googleCalendar.json","utf-8",false)

print "OAuth2 authorization granted!" + "\n";
print "New Access Token = " + oauth2.accessToken() + "\n";