Fetching multiple Gmail messages using API batch request

Other Questions Gmail
1

Hey folks, I’m having trouble with the Gmail API. I’m trying to get multiple messages using a batch request, but I’m running into an authentication issue. Here’s what I’m doing:

  1. I’m creating a batch request body with message IDs
  2. I’m including the OAuth2 access token in each request
  3. I’m sending a POST request to the Gmail batch endpoint

But I’m getting a 401 error saying the request is missing authentication. Here’s a simplified version of my code:

function fetchGmailBatch(auth, msgIds) {
  const batchBody = msgIds.map(id => (
    `--batch_boundary
    Authorization: Bearer ${auth.accessToken}
    Content-Type: application/http

    GET /gmail/v1/users/me/messages/${id}
    `
  )).join('\n');

  // Send POST request to batch endpoint
  // Parse response
}

Am I missing something in the authentication process? Or is there a better way to fetch multiple messages at once? Any help would be awesome!

2

I’ve been down this road before, and it can be tricky. One thing that worked for me was using the batch.execute() method from the Google API Client Library instead of manually constructing the batch request. It handles a lot of the authentication and formatting headaches for you.

Here’s a rough idea of how I approached it:

const google = require('googleapis').google;
const gmail = google.gmail({ version: 'v1', auth });

const batch = google.gmail({ version: 'v1', auth }).users.messages.get.batch();
msgIds.forEach(id => {
  batch.add(gmail.users.messages.get({ userId: 'me', id }));
});

batch.execute((err, responses) => {
  // Handle responses here
});

This method automatically takes care of authentication and request formatting. It’s been more reliable in my experience, and it’s easier to debug if something goes wrong. Just make sure your auth object is properly set up with the right scopes. Good luck with your project!

3

I’ve encountered this issue before while working with the Gmail API. One thing to consider is that batch requests handle authentication differently. Instead of including the Authorization header for each individual request in the batch, you should set it once for the entire batch request. Try modifying your code to include the Authorization header in the main POST request to the batch endpoint, rather than in each individual request within the batch. Also, ensure you’re using the correct Content-Type header for the batch request, which should be ‘multipart/mixed’. If you’re still facing issues, double-check that your OAuth2 flow is correctly implemented and that you’re using the appropriate scopes for the operations you’re trying to perform. Sometimes, permission-related problems can manifest as authentication errors.

4

hey danwilson85, i’ve had similar issues b4. try moving the Authorization header outside the batch requests. put it in the main POST request headers instead. also, make sure ur access token is fresh and not expired. hope this helps!