Xbase++

Download Object from Google Cloud Storage

See more Google Cloud Storage Examples

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

LOCAL nSuccess
LOCAL oSbToken
LOCAL oHttp
LOCAL cUrl
LOCAL oFileData
LOCAL oSbErrorResponse
LOCAL nResponseCode

nSuccess := 0

//  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..
oSbToken := CreateObject("Chilkat.StringBuilder")
oSbToken:LoadFile("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"

oHttp := CreateObject("Chilkat.Http")

oHttp:AuthToken := oSbToken:GetAsString()

//  Construct a URL to download an object named "starfish.jpg" from the "chilkat-ocean" bucket.
oHttp:SetUrlVar("bucket_name", "chilkat-ocean")
oHttp:SetUrlVar("object_name", "starfish.jpg")
cUrl := "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..
oFileData := CreateObject("Chilkat.BinData")
nSuccess := oHttp:DownloadBd(cUrl, oFileData)
IF (nSuccess == 0)
    ? oHttp:LastErrorText
    oSbToken:destroy()
    oHttp:destroy()
    oFileData:destroy()
    RETURN
ENDIF

oSbErrorResponse := CreateObject("Chilkat.StringBuilder")
nResponseCode := oHttp:LastStatus
IF (nResponseCode == 401)
    ? "If invalid credentials, then it is likely the access token expired."
    ? "Your app should automatically fetch a new access token and re-try."
ENDIF

IF (nResponseCode != 200)
    //  Get the error response
    oSbErrorResponse:AppendBd(oFileData, "utf-8", 0, 0)
    ? "Error response code = " + Str(nResponseCode)
    ? "Error:"
    ? oSbErrorResponse:GetAsString()
    oSbToken:destroy()
    oHttp:destroy()
    oFileData:destroy()
    oSbErrorResponse:destroy()
    RETURN
ENDIF

? "Success."

//  Save the downloaded data to a file.
nSuccess := oFileData:WriteFile("qa_output/starfish.jpg")

oSbToken:destroy()
oHttp:destroy()
oFileData:destroy()
oSbErrorResponse:destroy()