Gmail Api for Python returns Bad Request

Question

I'm using Gmail Api to send email in python but it looks like it doesn't work with Python 3.4.

Here is the code:

msg = MIMEText(html, 'html')
SCOPES = ['https://www.googleapis.com/auth/gmail.send']
username = '[email protected]'
CLIENT_SECRET_FILE = '/client_secret.json'  
credentials = ServiceAccountCredentials.from_json_keyfile_name(CLIENT_SECRET_FILE, SCOPES) 
try: 
     http_auth = credentials.authorize(Http()) 
     service = discovery.build('gmail', 'v1', http=http_auth) 
     gmailMsg = {'raw': base64.urlsafe_b64encode(msg.as_string().encode('utf-8')).decode('utf-8')} 
     message = (service.users().messages().send(userId = username, body = gmailMsg).execute())

Error:

<HttpError 400 when requesting https://www.googleapis.com/gmail/v1/users/me/messages/send?alt=json returned "Bad Request">

For the record, the credential I created for my project is a service account for non-ui platform (server-server). I thought that maybe the gmailMsg object wasn't encoded correctly. But when I used it in Google Apis Explorer, guess what: it worked. The only difference I can see is in Python, the JSON uses single quotation marks while in Google APIs Explorer, it foreced me to use double quotation marks.

Anyone has any recommendation?

P/S: I've tried following encoding options:

base64.urlsafe_b64encode(msg.as_string().encode('utf-8')).decode('utf-8')
base64.urlsafe_b64encode(msg.as_string().encode('utf-8')).decode('ascii')
base64.urlsafe_b64encode(msg.as_string().encode('ascii')).decode('ascii')
base64.urlsafe_b64encode(msg.as_bytes()).decode('utf-8')
base64.urlsafe_b64encode(msg.as_bytes()).decode('ascii')
base64.urlsafe_b64encode(msg.as_bytes()).decode()

Edit: Interestingly, i tried to use the Label Api which doesn't require body. But I got the same error. The only changes are:

SCOPES = ['https://www.googleapis.com/auth/gmail.labels']
message = (service.users().labels().list(userId = username).execute())

Tùng Trịnh Tùng Trịnh · Accepted Answer · 2017-04-12T19:34:50

It turns out that to use Gmail API I must use OAuth credential instead of Service account. In order to use Gmail API in a non UI system, you can initiate the authentication then copy the credential saved by the oauth api. Following is the code:

home_dir = os.path.expanduser('~')
credential_dir = os.path.join(home_dir, '.credentials')
if not os.path.exists(credential_dir):
    os.makedirs(credential_dir)
credential_path = os.path.join(credential_dir,
                               'gmail-api.json')

store = Storage(credential_path)
credentials = store.get()
f not credentials or credentials.invalid:
    flow = client.flow_from_clientsecrets(CLIENT_SECRET_FILE, SCOPES)
    flow.user_agent = APPLICATION_NAME
    if flags:
        credentials = tools.run_flow(flow, store, flags)
    else: # Needed only for compatibility with Python 2.6
        credentials = tools.run(flow, store)

Then you can use the gmail-api.json file to deploy on a non UI system to consume Gmail Api

Gmail Api for Python returns Bad Request

1 Answers