Is there a way in Gmail API to include extra fields (e.g. subject, body) in the message list method?

Question

The "Try it" part documentation allows me to play the API, and the field selector allow me to select a lot of fields, e.g. header, raw, etc. But none of them actually showed up when tried the API. The only thing I saw were still just the message ID and the thread ID.

https://developers.google.com/gmail/api/v1/reference/users/messages/list

E.g. The following:

GET https://www.googleapis.com/gmail/v1/users/{user_id}/messages?**fields=messages(historyId%2Cid%2Cpayload%2Craw%2CsizeEstimate%2Csnippet%2CthreadId)**&key={YOUR_API_KEY}

Returns:

{
 "messages": [
  {
   "id": "146da54fe3dc089e",
   "threadId": "146da54fe3dc089e"
  },
  {
   "id": "146da41d9486982f",
   "threadId": "146da41d9486982f"
  },
  ...
}

But I would expect the extra fields requested are returned too.

Is there a way to get this working? I know there is a separate method to get an individual message but like to get them batch if possible.

Answer 1

messages.list does not return much more than just the identifiers. not sure what the field selector is but i don't believe it's used.

however you can use a batched message.get to then retrieve many messages at once in a second call:

A batch request consists of multiple API calls combined into one HTTP request. This section describes the batch syntax in detail; later, there's an example.

Note: A set of n requests batched together counts toward your usage limit as n requests, not as one request. The batch request is taken apart into a set of requests before processing.

From: https://developers.google.com/storage/docs/json_api/v1/how-tos/batch

With the Gmail API and batch here're some sample code:

GTLBatchQuery *batchQuery = [GTLBatchQuery batchQuery];

[gmailMessageIds enumerateObjectsUsingBlock:^(NSNumber *messageId, NSUInteger idx, BOOL *stop) {
    GTLQueryGmail *query = [GTLQueryGmail queryForUsersMessagesGet];
    query.userId = self.account.email;
    query.identifier = [NSString stringWithFormat:@"%llx", [messageId unsignedLongLongValue]];
    query.format = kGTLGmailFormatRaw;

    [batchQuery addQuery:query];
}];


[self.gmailService executeQuery:batchQuery completionHandler:^(GTLServiceTicket *ticket, GTLBatchResult *result, NSError *error) {
    NSArray *gmailMessages = result.successes.allValues; // This is an array of GTLGmailMessage objects
    ... 
}];

Answer 2

Upon browsing the Google documentation, using the messages.get section, I was able to return all of the field values via json using the method getMessage(...).

In the original request you are given the id and threadId. Using the id we are able to return all messages by doing something like so:

ListMessagesResponse mResponse =
            service.users().messages().list(user).execute();

// This will return the json listed with the field methods id and threadId.
List<Message> messages = mResponse.getMessages();

// Parse the response
if(message.size() == 0){...}
else {
  for(Message msg: messages)
    *.getMessage(service,user,msg.getId());
}

The above is not exact code but, should provide you with an idea of how to approach this problem.