Zig

Download File (Stream to Local Filesystem)

See more Google Drive Examples

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

const std = @import("std");
const chilkat = @import("chilkat");

pub fn main(init: std.process.Init) !void {
    const alloc = init.arena.allocator();

    // 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.

    const g_auth = try chilkat.AuthGoogle.init();
    defer g_auth.deinit();
    g_auth.setAccessToken("GOOGLE_DRIVE_ACCESS_TOKEN");

    const rest = try chilkat.Rest.init();
    defer rest.deinit();

    // 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.
    const b_auto_reconnect = true;
    try rest.connect("www.googleapis.com", 443, true, b_auto_reconnect);

    // Provide the authentication credentials (i.e. the access token)
    rest.setAuthGoogle(g_auth) catch {};

    // ------------------------------------------------------------------------------
    // 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.
    const gd_cache = try chilkat.Cache.init();
    defer gd_cache.deinit();
    gd_cache.setLevel(0);
    gd_cache.addRoot("C:/ckCache/googleDrive");

    const file_id = gd_cache.fetchText(alloc, "testFolder/abc/123/penguins.jpg") catch {
        std.debug.print("Filepath not found in cache.\n", .{});
        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.
    const sb_path = try chilkat.StringBuilder.init();
    defer sb_path.deinit();
    sb_path.append("/drive/v3/files/") catch {};
    sb_path.append(file_id) catch {};
    rest.addQueryParam("alt", "media") catch {};

    // Create a stream object with a SinkFile set to the path where the downloaded file will go.
    const file_stream = try chilkat.Stream.init();
    defer file_stream.deinit();
    file_stream.setSinkFile("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, file_stream) catch {};

    // Download the file, streaming the content to the SinkFile.
    _ = rest.fullRequestNoBody(alloc, "GET", try sb_path.getAsString(alloc)) catch {
        std.debug.print("{s}\n", .{try rest.getLastErrorText(alloc)});
        return;
    };

    // A successful response will have a status code equal to 200.
    if (rest.getResponseStatusCode() != 200) {
        std.debug.print("response status code = {d}\n", .{rest.getResponseStatusCode()});
        std.debug.print("response status text = {s}\n", .{try rest.getResponseStatusText(alloc)});
        std.debug.print("response header: {s}\n", .{try rest.getResponseHeader(alloc)});
        return;
    }

    std.debug.print("File downloaded.\n", .{});
}