Using Gmail API to Send Attachments Larger than 10mb - ruby

Question

I'm struggling to find a good example of the full set of requests necessary to send an email through the Gmail API containing an attachment larger than 10mb.
I've seen https://developers.google.com/gmail/api/v1/reference/users/messages/send and https://developers.google.com/gmail/api/guides/uploads#resumable, but there's nothing that ties it all together.
We're using the ruby client, but we're unable to complete this flow. With the following code, we get the following error trying to make the second request: Google::APIClient::ClientError: Recipient address required
The full body of the response is the following:
{"error"=>{"errors"=>[{"domain"=>"global", "reason"=>"invalidArgument", "message"=>"Recipient address required"}], "code"=>400, "message"=>"Recipient address required"}}
Here's the code used to generate the request:
raw = Base64.urlsafe_encode64 message_string
result1 = api_client.execute!(
:api_method => gmail_api.users.messages.to_h['gmail.users.messages.send'],
:parameters => {
:uploadType => 'resumable',
:userId => 'me'
},
:headers => {
'Content-Type' => 'application/json',
'X-Upload-Content-Type' => 'message/rfc822',
'X-Upload-Content-Length' => raw.bytesize.to_s
}
)
upload_id = result1.headers['x-guploader-uploadid']
result2 = api_client.execute!(
:api_method => gmail_api.users.messages.to_h['upload.gmail.users.messages.send'],
:body_object => {
:raw => raw
},
:parameters => {
:uploadType => 'resumable',
:upload_id => upload_id,
:userId => 'me'
},
:headers => {
'Content-Type' => message.content_type,
'Content-Length' => raw.bytesize.to_s
}
)

Answer 1

So the issue (thank you to #tholle) was that when sending attachments greater than 5mb and less than 35mb (but also works on messages without attachments), you do NOT base64 encode the body of the request, and use multipart as the uploadType. Unfortunately the docs don't mention this at all, and the error messages don't indicate that either.
Here's a working example that was able to send a 20mb attachment. Hopefully this will help anyone else who has wasted countless hours trying to figure this one out!
result = api_client.execute!(
:api_method => gmail_api.users.messages.to_h['gmail.users.messages.send'],
:body => rfc822_message_string,
:parameters => {
:uploadType => 'multipart',
:userId => 'me'
},
:headers => {
'Content-Type' => 'message/rfc822',
}
)

Answer 2

I am working on a JavaScript client and I finally found a way to send email using resumable method. (Thank you #Tholle and #jwg2s). Although this is in JavaScript client it should work about the same in other client too.
This is what I did:
// MIME Mail Message data. Copied form above #Tholle 's message.
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