(Tcl) Download Object from Google Cloud Storage

Demonstrates how to download an object from Google Cloud Storage to a file.

Chilkat Tcl Extension Downloads Chilkat Tcl Extension Downloads

load ./chilkat.dll

# 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..
set sbToken [new_CkStringBuilder]

CkStringBuilder_LoadFile $sbToken "qa_data/tokens/googleCloudStorageAccessToken.txt" "utf-8"

# Send a GET equivalent to this curl command.

# curl -X GET \
#     -H "Authorization: Bearer [OAUTH2_TOKEN]" \
#     -o "[SAVE_TO_LOCATION]" \
#     "https://www.googleapis.com/storage/v1/b/[BUCKET_NAME]/o/[OBJECT_NAME]?alt=media"

set http [new_CkHttp]

CkHttp_put_AuthToken $http [CkStringBuilder_getAsString $sbToken]

# Construct a URL to download an object named "starfish.jpg" from the "chilkat-ocean" bucket.
CkHttp_SetUrlVar $http "bucket_name" "chilkat-ocean"
CkHttp_SetUrlVar $http "object_name" "starfish.jpg"
set url "https://www.googleapis.com/storage/v1/b/{$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..
set fileData [new_CkBinData]

set success [CkHttp_DownloadBd $http $url $fileData]
if {$success == 0} then {
    puts [CkHttp_lastErrorText $http]
    delete_CkStringBuilder $sbToken
    delete_CkHttp $http
    delete_CkBinData $fileData
    exit
}

set sbErrorResponse [new_CkStringBuilder]

set responseCode [CkHttp_get_LastStatus $http]
if {$responseCode == 401} then {
    puts "If invalid credentials, then it is likely the access token expired."
    puts "Your app should automatically fetch a new access token and re-try."
}

if {$responseCode != 200} then {
    # Get the error response
    CkStringBuilder_AppendBd $sbErrorResponse $fileData "utf-8" 0 0
    puts "Error response code = $responseCode"
    puts "Error:"
    puts [CkStringBuilder_getAsString $sbErrorResponse]
    delete_CkStringBuilder $sbToken
    delete_CkHttp $http
    delete_CkBinData $fileData
    delete_CkStringBuilder $sbErrorResponse
    exit
}

puts "Success."

# Save the downloaded data to a file.
set success [CkBinData_WriteFile $fileData "qa_output/starfish.jpg"]

delete_CkStringBuilder $sbToken
delete_CkHttp $http
delete_CkBinData $fileData
delete_CkStringBuilder $sbErrorResponse