Implementing Gmail API with OAuth 2.0 in Indy: How to?

Other Questions Gmail
1

Hey folks! I’m trying to figure out how to use the Gmail API with OAuth 2.0 in my Indy project. Right now, I’ve got some code that works, but it requires users to lower their Google account security settings. That’s not ideal.

Here’s what I’ve got so far:

procedure SendEmail(Sender, Recipient, Subject, Body: string);
var
  SMTP: TIdSMTP;
  Message: TIdMessage;
  SSLHandler: TIdSSLIOHandlerSocketOpenSSL;
begin
  SMTP := TIdSMTP.Create(nil);
  Message := TIdMessage.Create(nil);
  SSLHandler := TIdSSLIOHandlerSocketOpenSSL.Create(nil);
  try
    // Set up SSL
    SSLHandler.SSLOptions.Method := sslvTLSv1_2;
    
    // Configure SMTP
    SMTP.IOHandler := SSLHandler;
    SMTP.UseTLS := utUseExplicitTLS;
    SMTP.Host := 'smtp.gmail.com';
    SMTP.Port := 587;
    SMTP.Username := '[email protected]';
    SMTP.Password := 'your_password';
    
    // Set up message
    Message.From.Address := Sender;
    Message.Recipients.Add.Address := Recipient;
    Message.Subject := Subject;
    Message.Body.Text := Body;
    
    // Send email
    SMTP.Connect;
    try
      SMTP.Send(Message);
    finally
      SMTP.Disconnect;
    end;
  finally
    SMTP.Free;
    Message.Free;
    SSLHandler.Free;
  end;
end;

This works, but it’s not using OAuth 2.0. How can I update this to use the Gmail API with proper OAuth authentication? Any tips or code samples would be super helpful. Thanks!

2

hey mate, i feel ya. switching to oauth 2.0 is a pain but totally worth it. you’ll need to set up ur project in google dev console first. then use a oauth 2.0 client for token stuff. instead of smtp, you’ll be making api calls with the access token. it’s more work but way safer in the long run. good luck!

3

I’ve handled this transition before and can confirm that shifting to OAuth 2.0 with the Gmail API is a worthwhile improvement despite the added complexity. It requires starting with a project setup in the Google Developer Console to create your OAuth credentials, then using an OAuth 2.0 client to manage the token exchange. Rather than relying on SMTP, you adjust your approach to make RESTful API calls, using the access token for authentication. The process requires new handling for token refreshes and error management, but the resulting security gains make it a sensible change.

4

Implementing OAuth 2.0 with the Gmail API in Indy is indeed a significant upgrade from your current setup. You’ll need to restructure your approach quite a bit. First, obtain OAuth 2.0 credentials from the Google Developer Console. Then, implement a token management system to handle authorization and refresh tokens. For the actual email sending, you’ll switch from SMTP to making HTTP requests to the Gmail API endpoints. This involves constructing the email as a MIME message and sending it via a POST request. While it’s more complex initially, it provides better security and user experience. Consider using a library like Delphi REST Client to simplify API interactions. Remember to handle token expiration and refreshing appropriately in your code.