(JavaScript) Download Object from Google Cloud Storage

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

Note

This example is intended for running within a Chilkat.Js embedded JavaScript engine. All Chilkat JavaScript examples require Chilkat v11.4.0 or greater.

var success = false;

// 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..
var sbToken = new CkStringBuilder();
sbToken.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"

var http = new CkHttp();

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");
var 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..
var fileData = new CkBinData();
success = http.DownloadBd(url,fileData);
if (success == false) {
    console.log(http.LastErrorText);
    return;
}

var sbErrorResponse = new CkStringBuilder();
var responseCode = http.LastStatus;
if (responseCode == 401) {
    console.log("If invalid credentials, then it is likely the access token expired.");
    console.log("Your app should automatically fetch a new access token and re-try.");
}

if (responseCode !== 200) {
    // Get the error response
    sbErrorResponse.AppendBd(fileData,"utf-8",0,0);
    console.log("Error response code = " + responseCode);
    console.log("Error:");
    console.log(sbErrorResponse.GetAsString());
    return;
}

console.log("Success.");

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