Impossible to get messages details in a list request with Gmail API

Question

I am using a ruby on rails app which connects to the Gmail API. When I make a listrequest to get all the messages of one mailbox, I only get back an idand a threadId property for each message.

I tried to follow Gmail API Doc using the fields parameters to get other properties (title, date...). It doesn't work, whether I use the google-api-client gem in my app, or by doing a direct GET request.

Adding any other parameters to the request ends with a failure. Here is the url that works : https://www.googleapis.com/gmail/v1/users/me/messages?fields=messages(id,threadId)

Am I forced to make one call per message or using batch requests to get relevant datas ? It seems a little heavy...

Answer 1

You first need to list messages like you've done, and then get each message in a separate request.

Request 1

GET https://www.googleapis.com/gmail/v1/users/me/messages?maxResults=1&access_token={ACCESS_TOKEN}

Response 1

{
 "messages": [
  {
   "id": "15fd9f0fe242f975",
   "threadId": "15fd9f0fe242f975"
  }
 ],
 "nextPageToken": "11889180580605610074",
 "resultSizeEstimate": 2
}

Request 2

GET https://www.googleapis.com/gmail/v1/users/me/messages/15fd9f0fe242f975?access_token={ACCESS_TOKEN}

Response 2

{
 "id": "15fd9f0fe242f975",
 "threadId": "15fd9f0fe242f975",
 "labelIds": [
  "IMPORTANT",
  "CATEGORY_UPDATES",
  "INBOX"
 ],
 "snippet": "Tasks tracked last week...",
 "historyId": "966691",
 ...
}

It's also possible to get the total amount of request down from 1 + n of messages to 2 by using batch requests.