Keep getting invalid id value error message from Gmail api, users.messages.get

Question

I am trying to read one particular email from my Gmail inbox using Gmail API.

// Load client secrets from a local file.
fs.readFile('credential/credentials.json', (err, content) => {
  if (err) return console.log('Error loading client secret file:', err);
  // Authorize a client with credentials, then call the Gmail API.
  authorize(JSON.parse(content), listMessages);
});

function listMessages(oauth2Client, userId, query, callback) {
  const gmail = google.gmail('v1');
  gmail.users.messages.list({
    'auth': oauth2Client,
    'userId': userId,
    'q': query
  }, (err, resp) => {
    if(err) return console.log(err);
    callback(oauth2Client, JSON.stringify(resp.data.messages[0].id));
  });
}

function getMessage(oauth2Client, messageId, callback) {
  const gmail = google.gmail('v1');
  let base64 = require('js-base64').Base64;
  console.log(messageId);
  gmail.users.messages.get({
    'auth': oauth2Client,
    'userId': 'me',
    'id': messageId
  }, (err, resp) => {
    if(err) return console.log(err);
    //console.log(resp);
    //console.log(base64.decode(resp.payload.body.data.replace(/-/g, '+').replace(/_/g, '/')));
  });
}

function authorize(credentials, callback) {
  const {client_secret, client_id, redirect_uris} = credentials.installed;
  const oAuth2Client = new google.auth.OAuth2(
      client_id, client_secret, redirect_uris[0]);

  // Check if we have previously stored a token.
  fs.readFile(TOKEN_PATH, (err, token) => {
    if (err) return getNewToken(oAuth2Client, callback);
    oAuth2Client.setCredentials(JSON.parse(token));
    callback(oAuth2Client, "me", "Daily Coding Problem", getMessage);
  });
}

I keep getting the following error message after getMessage() is called.

errors: [
    {
      domain: 'global',
      reason: 'invalidArgument',
      message: 'Invalid id value'
    }
  ]

I tried using Gmail API directly by filling in the form below and I did get the message I was expecting. The Id I used was copied and pasted directly from messageId from getMessage() function. I do not understand why the same Id string was considered invalid by Gmail messages.get() function.

Answer 1

In this line of code:
callback(oauth2Client, JSON.stringify(resp.data.messages[0].id));

JSON.stringify() is adding extra " marks to the messageId thereby making it invalid. The response from gmail.users.messages.list() returns an array of objects with the messageId as a string so there is no need to stringify it.