DataFlex

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. DataFlex

Use ChilkatAx-win32.pkg

Procedure Test
    Boolean iSuccess
    Handle hoSbToken
    Handle hoHttp
    String sUrl
    Variant vFileData
    Handle hoFileData
    Handle hoSbErrorResponse
    Integer iResponseCode
    String sTemp1

    Move False To iSuccess

    // 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..
    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbToken
    If (Not(IsComObjectCreated(hoSbToken))) Begin
        Send CreateComObject of hoSbToken
    End
    Get ComLoadFile Of hoSbToken "qa_data/tokens/googleCloudStorageAccessToken.txt" "utf-8" To iSuccess

    // 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"

    Get Create (RefClass(cComChilkatHttp)) To hoHttp
    If (Not(IsComObjectCreated(hoHttp))) Begin
        Send CreateComObject of hoHttp
    End

    Get ComGetAsString Of hoSbToken To sTemp1
    Set ComAuthToken Of hoHttp To sTemp1

    // Construct a URL to download an object named "starfish.jpg" from the "chilkat-ocean" bucket.
    Get ComSetUrlVar Of hoHttp "bucket_name" "chilkat-ocean" To iSuccess
    Get ComSetUrlVar Of hoHttp "object_name" "starfish.jpg" To iSuccess
    Move "https://www.googleapis.com/storage/v1/b/{$bucket_name}/o/{$object_name}?alt=media" To sUrl

    // If there is an error response, then we didn't actually download the file data,
    // but instead we downloaded an error response..
    Get Create (RefClass(cComChilkatBinData)) To hoFileData
    If (Not(IsComObjectCreated(hoFileData))) Begin
        Send CreateComObject of hoFileData
    End
    Get pvComObject of hoFileData to vFileData
    Get ComDownloadBd Of hoHttp sUrl vFileData To iSuccess
    If (iSuccess = False) Begin
        Get ComLastErrorText Of hoHttp To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Get Create (RefClass(cComChilkatStringBuilder)) To hoSbErrorResponse
    If (Not(IsComObjectCreated(hoSbErrorResponse))) Begin
        Send CreateComObject of hoSbErrorResponse
    End
    Get ComLastStatus Of hoHttp To iResponseCode
    If (iResponseCode = 401) Begin
        Showln "If invalid credentials, then it is likely the access token expired."
        Showln "Your app should automatically fetch a new access token and re-try."
    End

    If (iResponseCode <> 200) Begin
        // Get the error response
        Get pvComObject of hoFileData to vFileData
        Get ComAppendBd Of hoSbErrorResponse vFileData "utf-8" 0 0 To iSuccess
        Showln "Error response code = " iResponseCode
        Showln "Error:"
        Get ComGetAsString Of hoSbErrorResponse To sTemp1
        Showln sTemp1
        Procedure_Return
    End

    Showln "Success."

    // Save the downloaded data to a file.
    Get ComWriteFile Of hoFileData "qa_output/starfish.jpg" To iSuccess


End_Procedure