(Node.js) Download File (Stream to Local Filesystem)

This example demonstrates how to download the content of a file from Google Drive. The file is streamed to the local filesystem.

Install Chilkat for Node.js and Electron using npm at Chilkat npm packages for Node.js Chilkat npm packages for Electron on Windows, Linux, MacOSX, and ARM

var os = require('os');
if (os.platform() == 'win32') {  
    if (os.arch() == 'ia32') {
        var chilkat = require('@chilkat/ck-node21-win-ia32');
    } else {
        var chilkat = require('@chilkat/ck-node21-win64'); 
    }
} else if (os.platform() == 'linux') {
    if (os.arch() == 'arm') {
        var chilkat = require('@chilkat/ck-node21-arm');
    } else if (os.arch() == 'x86') {
        var chilkat = require('@chilkat/ck-node21-linux32');
    } else {
        var chilkat = require('@chilkat/ck-node21-linux64');
    }
} else if (os.platform() == 'darwin') {
    if (os.arch() == 'arm64') {
        var chilkat = require('@chilkat/ck-node21-mac-m1');
    } else {
        var chilkat = require('@chilkat/ck-node21-macosx');
    }
}

function chilkatExample() {

    var success = true;

    // It 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 
    // Google Drive scope.

    var gAuth = new chilkat.AuthGoogle();
    gAuth.AccessToken = "GOOGLE_DRIVE_ACCESS_TOKEN";

    var rest = new chilkat.Rest();

    // Connect using TLS.
    // A single REST object, once connected, can be used for many Google Drive REST API calls.
    // The auto-reconnect indicates that if the already-established HTTPS connection is closed,
    // then it will be automatically re-established as needed.
    var bAutoReconnect = true;
    success = rest.Connect("www.googleapis.com",443,true,bAutoReconnect);

    // Provide the authentication credentials (i.e. the access token)
    rest.SetAuthGoogle(gAuth);

    // ------------------------------------------------------------------------------
    // To download a file, we must know the file ID.
    // In a previous example (see Build Local Metadata Cache
    // we built a local cache to make it easy to lookup file IDs given a file path.
    // Let's say we want to download "testFolder/abc/123/penguins.jpg".
    // First we lookup the fileId in the cache.  With the fileId, we can download the file.
    var gdCache = new chilkat.Cache();
    gdCache.Level = 0;
    gdCache.AddRoot("C:/ckCache/googleDrive");

    var fileId = gdCache.FetchText("testFolder/abc/123/penguins.jpg");
    if (gdCache.LastMethodSuccess !== true) {
        console.log("Filepath not found in cache.");
        return;
    }

    // We need to send a GET request like this:
    // GET https://www.googleapis.com/drive/v3/files/fileId?alt=media
    // The fileId is part of the path.
    var sbPath = new chilkat.StringBuilder();
    sbPath.Append("/drive/v3/files/");
    sbPath.Append(fileId);
    rest.AddQueryParam("alt","media");

    // Create a stream object with a SinkFile set to the path where the downloaded file will go.
    var fileStream = new chilkat.Stream();
    fileStream.SinkFile = "qa_output/penguins.jpg";
    // Indicate that the response body should stream directly to fileStream,
    // but only if the response status is 200.  
    rest.SetResponseBodyStream(200,true,fileStream);

    // Download the file, streaming the content to the SinkFile.
    var jsonResponse = rest.FullRequestNoBody("GET",sbPath.GetAsString());
    if (rest.LastMethodSuccess !== true) {
        console.log(rest.LastErrorText);
        return;
    }

    // A successful response will have a status code equal to 200.
    if (rest.ResponseStatusCode !== 200) {
        console.log("response status code = " + rest.ResponseStatusCode);
        console.log("response status text = " + rest.ResponseStatusText);
        console.log("response header: " + rest.ResponseHeader);
        return;
    }

    console.log("File downloaded.");

}

chilkatExample();