Attaching a file using Resumable upload w/ Gmail API - gmail

Question

I am attempting to use Gmail's Resumable option for uploading attachments to an email. Documentation reference: https://developers.google.com/gmail/api/guides/uploads#resumable.
Currently I am able to send the email with the resumable URI, but without an attachment (using Postman). Documentation doesn't provide very clear examples of what the request should specifically look like, and there don't seem to be many examples after scouring the internet.
My requests are in two parts:
Initial request -
Request URL:
POST /upload/gmail/v1/users/me/messages/send?uploadType=resumable
Host: www.googleapis.c om (can't post links so I interrupted the url)
Headers:
Authorization: Bearer my_token_here
Content-Length: 113
Content-Type: application/json
X-Upload-Content-Length: 67
X-Upload-Content-Type: message/rfc822
Body:
{"raw":"VG86IG5pcnZhbmEucm9ja2VyQGdtYWlsLmNvbQpTdWJqZWN0OiBUZXN0RW1haWxTdWJqZWN0MwoKTWVzc2FnZSBjb250ZW50cyAjMy4"}
The body is a 64bit encoded string that include the To, Subject, and email message contents. Then gmail returns a response with an empty body, and a 'location' header that looks like the following: googleapis.com/upload/gmail/v1/users/me/messages/send?uploadType=resumable&upload_id=BRnB2UoAsKwzNMoQAy-JtmP6mu5agltqOWZ9uerI3k-KNTDJ73PWEjKuAHpko4RN6weSEysddH2kjj4G24uFw6E9oPv1XP69l7_KcmNuW-RAoz_5oS1T_4_E. (removed https:// because this account can only have one link in a post)
I then follow up with a PUT request to that URL returned in the location header.
The second request looks like the following:
Request URL:
PUT /upload/gmail/v1/users/me/messages/send?uploadType=resumable&upload_id=BRnB2UoAsKwzNMoQAy-JtmP6mu5agltqOWZ9uerI3k-KNTDJ73PWEjKuAHpko4RN6weSEysddH2kjj4G24uFw6E9oPv1XP69l7_KcmNuW-RAoz_5oS1T_4_E
Host: www.googleapis.c om
Headers:
Content-Length: 67
Content-Type: message/rfc822
Body:
{"raw":"VG86IG5pcnZhbmEucm9ja2VyQGdtYWlsLmNvbQpTdWJqZWN0OiBUZXN0RW1haWxTdWJqZWN0MwoKTWVzc2FnZSBjb250ZW50cyAjMy4"}
--- OR ---
I choose the binary option, and attach the file I am looking to upload via Postman.
I receive a response from Gmail with an object like this:
{
"id": "159d7ded3125e255",
"threadId": "159d7ded3125e255",
"labelIds": [
"SENT"
]
}
And an email is sent successfully, however there isn't an attachment with the email. When I show the original email in Gmail, there isn't any evidence of an attachment. Original looks like the following:
Received: from 325276275830 named unknown by gmailapi.google.com with HTTPREST; Wed, 25 Jan 2017 15:03:33 -0800
To: some.name#gmail.com
Subject: TestEmailSubject3
Date: Wed, 25 Jan 2017 15:03:33 -0800
Message-Id: <CEROA6F=0ohk33RD9XyC_gW1DZO88xYF4bXYqrCSct62MUuytDw#mail.gmail.com>
From: name_here#gmail.com
Message contents #3.
What am I missing? Do I need to encode some particular contents in a different way, or put some data in a different location? I'm not receiving any errors. I've been working on this for a few days now and I just can't figure it out.

Answer 1

I ran into the same problem, i made it work by using Nodemailer to create the email with the attachments, save the result to a file, then upload it with this.

Answer 2

Instead of send email in two parts you can send all your email data and attachment data as a mime message. like this.
I am using JavaScript client so you can do like this:
// MIME Mail Message data.
let mail = [
'Content-Type: multipart/mixed; boundary="foo_bar_baz"\r\n',
"MIME-Version: 1.0\r\n",
"to: to#gmail.com\r\n",
"from: from#gmail.com\r\n",
"subject: i am subject\r\n\r\n",
"--foo_bar_baz\r\n",
'Content-Type: text/plain; charset="UTF-8"\r\n',
"MIME-Version: 1.0\r\n",
"Content-Transfer-Encoding: 7bit\r\n\r\n",
"The actual message text goes here\r\n",
"--foo_bar_baz\r\n",
"Content-Type: application/json; name=package.json\r\n",
"Content-Transfer-Encoding: base64\r\n",
"Content-Disposition: attachment; filename=package.json\r\n\r\n",
"<base64 file data. data according to content type>",
"\r\n",
"--foo_bar_baz--",
].join("");
// get resumable upload link.
let resumableURL = "";
gapi.client
.request({
path: "/upload/gmail/v1/users/me/messages/send?uploadType=resumable",
headers: {
"X-Upload-Content-Type": "message/rfc822",
},
method: "post",
})
.then(
(res) => {
resumableURL = res.headers.location;
console.log(res);
},
(err) => console.log(err)
);
// send email
gapi.client
.request({
path: resumableURL,
headers: {
"Content-Type": "message/rfc822",
},
method: "post",
body: mail,
})
.then(
(res) => {
console.log(res);
},
(err) => console.log(err)
);
To convert gapi.client.request to Fetch API call you just need to add Authorization: Bearer <access_token> to header field. I have tried using Fetch API but response were blocked due to cors error so api client like Postman should be used.
To do more with resumable upload method check documentation: Upload Attachment