Auth0: Link Accounts with Same Email Address while Merging Metadata

link-accounts.js

function (user, context, callback) {
  var request = require('request@2.56.0');
  var async = require('async@2.1.2');

  // Check if email is verified, we shouldn't automatically
  // merge accounts if this is not the case.
  if (!user.email_verified) {
    return callback(null, user, context);
  }
  var userApiUrl = auth0.baseUrl + '/users';
  user.app_metadata = user.app_metadata || {};
  user.user_metadata = user.user_metadata || {};

  request({
   url: userApiUrl,
   headers: {
     Authorization: 'Bearer ' + auth0.accessToken
   },
   qs: {
     search_engine: 'v2',
     q: 'email.raw:"' + user.email + '" -user_id:"' + user.user_id + '"',
   }
  },
  function(err, response, body) {
    if (err) return callback(err);
    if (response.statusCode !== 200) return callback(new Error(body));

    var data = JSON.parse(body);

    // Put the oldest last so it will overwrite the newest
    data.sort(function(a, b) {
      return b.date.localeCompare(a.date);
    });

    var linkUsers = data.filter(function(targetUser) {
      if (targetUser.email_verified) {
        Object.assign(user.app_metadata, targetUser.app_metadata);
        Object.assign(user.user_metadata, targetUser.user_metadata);
        return true;
      }
    });

    if (!linkUsers.length) {
      return callback(null, user, context);
    }

    // save metadata, the oldest should overwrite the newest
    auth0.users.updateAppMetadata(user.user_id, user.app_metadata)
    .then(auth0.users.updateUserMetadata(user.user_id, user.user_metadata))
    .then(function() {
      async.each(linkUsers, function(targetUser, cb) {
        var aryTmp = targetUser.user_id.split('|');
        var provider = aryTmp[0];
        var targetUserId = aryTmp[1];
        console.log('Joining:', { provider: provider, user_id: targetUserId });
        request.post({
          url: userApiUrl + '/' + user.user_id + '/identities',
          headers: {
            Authorization: 'Bearer ' + auth0.accessToken
          },
          json: { provider: provider, user_id: targetUserId }
        }, function(err, response, body) {
          if (response.statusCode >= 400) {
            cb(new Error('Error linking account: ' + response.statusMessage));
          }
          if (!err) {
            user.identities.push.apply(user.identities, targetUser.identities);
          }
          cb(err);
        });
      }, function(err) {
        callback(err, user, context);
      });
    }).catch(function(err) {
      callback(err, user, context);
    });
  });
}