(Chilkat2-Python) Refresh Access Token on 401 Unauthorized and Retry (Service Account)

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Demonstrates how to handle an expired access token error, refresh the token, and retry the request. (In this case, the request is to download an object from Google Cloud Storage.)

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import sys
import chilkat2

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

# This example uses a previously obtained access token having permission for the 
# scope "https://www.googleapis.com/auth/cloud-platform"

# In this example, Get Google Cloud Storage OAuth2 Access Token, 
# the service account access token was saved to a text file.  This example fetches the access token from the file..
sbToken = chilkat2.StringBuilder()
success = sbToken.LoadFile("qa_data/tokens/googleCloudStorageAccessToken.txt","utf-8")
if (success == False):
    print("Failed to load access token.")
    sys.exit()

http = chilkat2.Http()

http.AuthToken = sbToken.GetAsString()

# Construct a URL to download an object named "starfish.jpg" from the "chilkat-ocean" bucket.
http.SetUrlVar("bucket_name","chilkat-ocean")
http.SetUrlVar("object_name","starfish.jpg")
url = "https://www.googleapis.com/storage/v1/b/{$bucket_name}/o/{$object_name}?alt=media"

# If there is an error response, then we didn't actually download the file data,
# but instead we downloaded an error response..
fileData = chilkat2.BinData()
success = http.DownloadBd(url,fileData)
responseCode = http.LastStatus
if ((success == False) and (responseCode != 401)):
    print(http.LastErrorText)
    sys.exit()

if (responseCode == 401):
    print("Received 401 Unauthorized response. Attempting to refresh the access token...")

    # May be that the access token expired.
    # Load our JSON key and request a new access token, then retry the original request.
    fac = chilkat2.FileAccess()
    jsonKey = fac.ReadEntireTextFile("qa_data/googleApi/ChilkatCloud-13a07a2e8b3f.json","utf-8")
    if (fac.LastMethodSuccess != True):
        print(fac.LastErrorText)
        sys.exit()

    gAuth = chilkat2.AuthGoogle()
    gAuth.JsonKey = jsonKey
    gAuth.Scope = "https://www.googleapis.com/auth/cloud-platform"
    gAuth.ExpireNumSeconds = 3600
    gAuth.SubEmailAddress = ""

    tlsSock = chilkat2.Socket()
    success = tlsSock.Connect("www.googleapis.com",443,True,5000)
    if (success != True):
        print(tlsSock.LastErrorText)
        sys.exit()

    success = gAuth.ObtainAccessToken(tlsSock)
    if (success != True):
        print(gAuth.LastErrorText)
        sys.exit()

    fac.WriteEntireTextFile("qa_data/tokens/googleCloudStorageAccessToken.txt",gAuth.AccessToken,"utf-8",False)

    # Retry the original request.
    http.AuthToken = gAuth.AccessToken
    success = http.DownloadBd(url,fileData)
    if (success == False):
        print(http.LastErrorText)
        sys.exit()

if (responseCode != 200):
    # Get the error response
    sbErrorResponse = chilkat2.StringBuilder()
    sbErrorResponse.AppendBd(fileData,"utf-8",0,0)
    print("Error response code = " + str(responseCode))
    print("Error:")
    print(sbErrorResponse.GetAsString())
    sys.exit()

print("Success.")

# Save the downloaded data to a file.
success = fileData.WriteFile("qa_output/starfish.jpg")