How to `insert` a `full` format message using the Gmail API?

Question

I've had success cloning a 'raw' formatted message by using get with format='raw' and re-inserting it just like this:

params = {'userId':'me", 'id': msg_id, 'format':'raw'}
mesg = service.users().messages().get(**params).execute()

body = {'raw': mesg['raw']}
service.users().messages().insert(userId='me', body=**body).execute()

But I'm keen to do the same thing using the json format that get can alternatively return via format='full'. Something like this:

params = {'userId':'me", 'id': msg_id, 'format':'full'}
mesg = service.users().messages().get(**params).execute()

body = mesg
service.users().messages().insert(userId='me', body=**body).execute()

See below for the format of mesg[1]. Doing the above gives me the error:

HttpError: <HttpError 400 when requesting 
  https://www.googleapis.com/gmail/v1/users/me/messages?alt=json 
  returned "
  'raw' RFC822 payload message string or uploading message via /upload/* 
   URL required
">

So the question is:

How do I insert a message via the 'full' json format?

The format is 'full' not 'raw' so should I use the upload url? How? Do we continue with a json payload in the raw or body somehow?
Can we convert it to raw format then do same as before?
Should I try and work out how to use the upload with this format?
Should I give it up and work with the raw format?
Will I just hear crickets in response to this question?
So many questions.

---

The messages get documentation is here
The messages insert documentation is here

[1] A full format get returns this kind of thing. And this is what I'm hoping to insert somehow.

{u'historyId': u'5226', u'id': u'148af993efc00bce',
 u'snippet': u'Hi Joe Get the official Gmail app The best features of Gmail are only available on your phone and',
 u'sizeEstimate': 4809, u'threadId': u'148af993efc00bce', u'labelIds': [u'INBOX'],
 u'payload': {u'mimeType': u'multipart/alternative', u'headers': [
      {u'name': u'MIME-Version', u'value': u'1.0'},
      {u'name': u'x-no-auto-attachment', u'value': u'1'},
      {u'name':
           {u'historyId': u'5226',
            u'id': u'148af993efc00bce',
            u'snippet': u'Hi Joe Get the official Gmail app The best features of Gmail are only available on your phone and',
            u'sizeEstimate': 4809,
            u'threadId': u'148af993efc00bce',
            u'labelIds': [u'INBOX'], u'payload': {
               u'mimeType': u'multipart/alternative',
               u'headers': [{u'name': u'MIME-Version',
                             u'value': u'1.0'}, {
                                u'name': u'x-no-auto-attachment',
                                u'value': u'1'},
                            {u'name': u'Received',
                             u'value': u'by 10.31.41.213; Thu, 25 Sep 2014 18:35:28 -0700 (PDT)'},
                            {u'name': u'Date',
                             u'value': u'Thu, 25 Sep 2014 18:35:28 -0700'},
                            {u'name': u'Message-ID',
                             u'value': u'<CAJvL7e8jz9WYNUjHgnmYcyFgySXxjLiH1zjMxOfopURZmAy4iA@mail.gmail.com>'},
                            {u'name': u'Subject',
                             u'value': u'The best of Gmail, wherever you are'},
                            {u'name': u'From',
                             u'value': u'Gmail Team <[email protected]>'},
                            {u'name': u'To',
                             u'value': u'Joe Test <[email protected]>'},
                            {u'name': u'Content-Type',
                             u'value': u'multipart/alternative; boundary=bcaec547c84f9cba4a0503edee6b'}],
               u'parts': [{u'mimeType': u'text/plain',
                           u'headers': [
                               {u'name': u'Content-Type',
                                u'value': u'text/plain; charset=UTF-8'},
                               {
                                   u'name': u'Content-Transfer-Encoding',
                                   u'value': u'quoted-printable'}],
                           u'body': {
                               u'data': u'IFRoZSBiZXN0IG9mIEdtYWlsLCB3aGVyZ...

Answer 1

You cannot insert a FULL formatted message. If you use the /upload URL then you need an uploadType string and you should have a content-type of message/rfc822. If you're not using /upload then you simply post something like:

{
  'message': 
  {
     'raw': base64url("From: me\r\nTo: someguy\r\nSubject: here it is\r\n\r\nbody after blank line.")
  }
}

you can use attachments but then you'll likely want some mime email libraries to help you generate that email message string that gets base64url encoded in the raw field.