How to send an email

[lamafab]

Hello

Could you please clarify how one sends an email? Once you have the UserMessageSendCall type, the only options I see to continue are upload and upload_resumable. How does one just send the message without any file?

[Byron]

Generally I recommend going by examples in the official documentation and then trying to map this to the generated types and methods provided here.

This project is about generating crates based on an API description and thus can't provide any support on how to use the generated crates, beyond addressing bugs and shortcomings of course.

[jacek-kurlit]

I have decided to answer this question after struggling to send any email.
I had big problems since for me this API is not very intuitive.
Please bear in mind that I'm not sure if this is correct way but it works in my project.

use std::{fs, io::Cursor, path::PathBuf};

use google_gmail1::{
    api::Message,
    hyper::{self, client::HttpConnector},
    hyper_rustls::{self, HttpsConnector},
    oauth2::{self, authenticator_delegate::InstalledFlowDelegate},
    Gmail,
};
use lettre::message::{header, Body, MultiPart, SinglePart};

use crate::{google_api::load_secret, models::AppError};

pub async fn send_email(
    topic: &str,
    content: &str,
    gpc_path: PathBuf,
    token_store_path: PathBuf,
    flow_delegate: Box<dyn InstalledFlowDelegate>,
) -> Result<(), AppError> {
    let gmail = create_gmail_service(gpc_path, token_store_path, flow_delegate).await?;
    let pdf = fs::read("/path/to/sample.pdf")?;
    let pdf_body = Body::new(pdf);

    let email = lettre::Message::builder()
        .from("from@gmail.com".parse().unwrap())
        .to("to@gmail.com".parse().unwrap())
        .subject(topic)
        .multipart(
            MultiPart::mixed()
                .singlepart(
                    SinglePart::builder()
                        .header(header::ContentType::parse("text/plain; charset=utf8")?)
                        .body(content.to_string()),
                )
                .singlepart(
                    SinglePart::builder()
                        .header(header::ContentType::parse("application/pdf")?)
                        .header(header::ContentDisposition::attachment("output.pdf"))
                        .body(pdf_body),
                ),
        )
        .map_err(|e| AppError::Internal(e.to_string()))?;
    let response = gmail
        .users()
        .messages_send(Message::default(), "me")
        .upload_resumable(
            Cursor::new(email.formatted()),
            "message/rfc822".parse().expect("mime rfc822 is valid"),
        )
        .await?;
    println!("response: {:?}", response);

    Ok(())
}

Technically gmail expects data in rfc822 format which can be provided in Message.raw but we are still obligated by .upload_resumable() to give some kind of data which is misleading. Therefore I'm using lettre crate to create rfc822 data and feed it to this method. As result I have received email with topic, content and pdf attachment.
I hope this will help someone

[Byron]

Thanks so much for sharing! I truly wish that Google would finally provide their own bindings - these ones have been created many years ago and were barely ever used. Thus they are certainly not as good as they could be.

[lamafab]

APIs are hard, I guess