Rust

Refresh GMail SMTP OAuth2 Access Token

See more OAuth2 Examples

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

// 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).

let json_token = chilkat::JsonObject::new();
if json_token.load_file("qa_data/tokens/_gmailSmtp.json").is_err() {
    println!("Failed to load _gmailSmtp.json");
    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"
// 	}
// 

let oauth2 = chilkat::OAuth2::new();

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

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

// Get the "refresh_token"
oauth2.set_refresh_token(&json_token.string_of("refresh_token").unwrap_or_default());

// Send the HTTP POST to refresh the access token..
if oauth2.refresh_access_token().is_err() {
    println!("{}", oauth2.last_error_text());
    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.
let _ = json_token.update_string("access_token", &oauth2.access_token());

// Save the new JSON access token response to a file.
let sb_json = chilkat::StringBuilder::new();
json_token.set_emit_compact(false);
let _ = json_token.emit_sb(&sb_json);
let _ = sb_json.write_file("qa_data/tokens/_gmailSmtp.json", "utf-8", false);

println!("OAuth2 authorization granted!");
println!("New Access Token = {}", oauth2.access_token());