TS - NodeMailer OAuth2 'auth' does not exist in type 'TransportOptions - node.js

Question

I have a problem. I need to make email sending function with Gmail api. In docs it tells me to make a createTransport function like this:
const transport = nodemailer.createTransport({
service: "gmail",
auth: {
type: "OAuth2",
user: "horvatlucian1#gmail.com",
clientId: CLIENT_ID,
clientSecret: CLIENT_SECRET,
refreshToken: REFRESH_TOKEN,
accessToken: accessToken,
},
})
DOCS
But it all turns red and returns:
Error
Any solution? Thanks.

Answer 1

There is a problem of type script when you tring to pass the accessToken because in google oauth2client the return type of getAccessToken() is https://github.com/googleapis/google-auth-library-nodejs/blob/b0ddb7512fb9ed1e51b6874b7376d7e1f26be644/src/auth/oauth2client.ts#L331
that not supported by the types of nodemailer that should be string:
https://github.com/DefinitelyTyped/DefinitelyTyped/blob/7827d853a1d623dd5345d9a11ced3e15eb5d3d8b/types/nodemailer/lib/xoauth2.d.ts#L24
by looking at the return type of the getAccessToken you can see that the token is inside that have type string so to fix that just destructure your token from the accessToken.
const transport = nodemailer.createTransport({
service: "gmail",
auth: {
type: "OAuth2",
user: "horvatlucian1#gmail.com",
clientId: CLIENT_ID,
clientSecret: CLIENT_SECRET,
refreshToken: REFRESH_TOKEN,
accessToken: accessToken.token,
},
})

Answer 2

1/
const transport = nodemailer.createTransport({
service: String("gmail") || "",
auth: {
type: String("OAuth2"),
user: String(SENDER_MAIL),
clientId: String(CLIENT_ID),
clientSecret: String(CLIENT_SECRET),
refreshToken: String(REFRESH_TOKEN),
access_token: String(access_token),
},
});
and the ERRO WITH MSG :
[ERROR] 14:02:23 ⨯ Unable to compile TypeScript:
server/config/sendmail.ts(25,7): error TS2769: No overload matches this call.
The last overload gave the following error.
Argument of type '{ service: string; auth: { type: string; user: string; clientId:string; clientSecret:string; refreshToken:string; access_token:GetAccessTokenResponse; }; }' is not assignable to parameter of type 'TransportOptions | Transport<unknown>'.
Object literal may only specify known properties, and 'service' does not exist in type 'TransportOptions | Transport<unknown>'.

Answer 3

The accessToken required in nodemailer.createTransport is nullable
Because of that, to avoid error, you must cover the case when accessToken is null by providing an empty string or something similar to avoid null error
const transport = nodemailer.createTransport({
service: 'gmail',
auth: {
type: 'OAuth2',
user: process.env.EMAIL_ADDRESS,
clientId: process.env.CLIENT_ID,
clientSecret: process.env.CLIENT_SECRET,
refreshToken: process.env.REFRESH_TOKEN,
accessToken: accessToken.token || '',
},
})
Hopefully that help