Node.js

Download Binary File to In-Memory Bytes

See more Google Drive Examples

This example demonstrates how to download the binary content of a file from Google Drive directly into local memory. Node.js

NODEJS_PRELUDE

function chilkatExample() {

    var success = false;

    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");

    //  To download to memory, we'll send the request in one call, then receive
    //  the response header, and then the response body.
    //  If the response header indicates failure or an unexpected response, then the
    //  body is not the data we desire.

    //  First send the HTTP request.
    success = rest.SendReqNoBody("GET",sbPath.GetAsString());
    if (success !== true) {
        console.log(rest.LastErrorText);
        return;
    }

    //  Get the response header.
    var statusCode = rest.ReadResponseHeader();
    if (statusCode !== 200) {
        console.log("response status code = " + rest.ResponseStatusCode);
        console.log("response status text = " + rest.ResponseStatusText);
        console.log("response header: " + rest.ResponseHeader);

        //  Read the response body (which should be error text or HTML)
        var errResponseBody = rest.ReadRespBodyString();
        if (rest.LastMethodSuccess == true) {
            console.log("response body: " + errResponseBody);
        }

        return;
    }

    //  Read the response body, which should contain the file data.

    jpgBytes = rest.ReadRespBodyBinary();
    if (rest.LastMethodSuccess !== true) {
        console.log(rest.LastErrorText);
        return;
    }

    //  Save jpgBytes to a file so we can examine the file to verify that it worked.
    var fac = new chilkat.FileAccess();
    fac.WriteEntireFile("qa_output/penguins_out.jpg",jpgBytes);

    console.log("File downloaded.");

}

chilkatExample();