Zig

Refresh GMail SMTP OAuth2 Access Token

See more OAuth2 Examples

Demonstrates how to refresh an access token for sending email via GMail (SMTP). Zig

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

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

    // This example requires the Chilkat API to have been previously unlocked.
    // See Global Unlock Sample for sample code.

    // See Get GMail SMTP Access Token
    // for sample code showing how to obtain a GMail SMTP access token for desktop apps.

    // It is assumed we previously obtained an OAuth2 access token for GMail (one with a scope for sending email).

    const json_token = try chilkat.JsonObject.init();
    defer json_token.deinit();
    json_token.loadFile("qa_data/tokens/_gmailSmtp.json") catch {
        std.debug.print("Failed to load _gmailSmtp.json\n", .{});
        return;
    };

    // The access token JSON looks something like this:

    //     {
    //      "access_token": "abac.Ci-ZabcdF37-NUrmSzxbHxTsMbtlN-uPfabcdAQN_2ekzj0s5ofCzRabcdTDMGaa2Q",
    //      "token_type": "Bearer",
    //      "expires_in": 3600,
    //      "refresh_token": "1/lEe5abcdNJ77eOSDBabcdkQGVmDalkwabcdR2Hatbo"
    //     }
    //

    const oauth2 = try chilkat.OAuth2.init();
    defer oauth2.deinit();

    oauth2.setTokenEndpoint("https://www.googleapis.com/oauth2/v4/token");

    // Replace these with actual values.
    oauth2.setClientId("GOOGLE-CLIENT-ID");
    oauth2.setClientSecret("GOOGLE-CLIENT-SECRET");

    // Get the "refresh_token"
    oauth2.setRefreshToken(try json_token.stringOf(alloc, "refresh_token"));

    // Send the HTTP POST to refresh the access token..
    oauth2.refreshAccessToken() catch {
        std.debug.print("{s}\n", .{try oauth2.getLastErrorText(alloc)});
        return;
    };

    // The response contains a new access token, but we must keep
    // our existing refresh token for when we need to refresh again in the future.
    json_token.updateString("access_token", try oauth2.getAccessToken(alloc)) catch {};

    // Save the new JSON access token response to a file.
    const sb_json = try chilkat.StringBuilder.init();
    defer sb_json.deinit();
    json_token.setEmitCompact(false);
    json_token.emitSb(sb_json) catch {};
    sb_json.writeFile("qa_data/tokens/_gmailSmtp.json", "utf-8", false) catch {};

    std.debug.print("OAuth2 authorization granted!\n", .{});
    std.debug.print("New Access Token = {s}\n", .{try oauth2.getAccessToken(alloc)});
}