Minimal code demonstrating issue with idAttribute and relations in bookshelf.js

sample_bookshelf_relation_error.js

var knex = require('knex')({
  client: 'postgresql',
  connection: {
    host     : '127.0.0.1',
    user     : 'username',
    password : 'password',
    database : 'database'
  }
});

var Bookshelf = require('bookshelf')(knex);
var _ = require('underscore');
_.str = require('underscore.string');

function snakeToCamel(attrs) {
  return _.reduce(attrs, function(result, val, key) {
    result[_.str.camelize(key)] = val;
    return result;
  }, {});
}

function camelToSnake(attrs) {
  return _.reduce(attrs, function(result, val, key) {
    result[_.str.underscored(key)] = val;
    return result;
  }, {});
}

var UserType = Bookshelf.Model.extend({
  tableName: 'bookbrainz.user_type',
  idAttribute: 'userTypeId',
  parse: snakeToCamel,
  format: camelToSnake
});

var User = Bookshelf.Model.extend({
  tableName: 'bookbrainz.user',
  idAttribute: 'userId',
  parse: snakeToCamel,
  format: camelToSnake,
  hidden: ['password'],
  userType: function() {
    return this.belongsTo(UserType, 'user_type_id');
  }
});

new User({userId: 4}).fetch({withRelated: ['userType']}).then(function() {
  process.exit();
});

// Unhandled rejection error:
// select "bookbrainz"."user_type".* from "bookbrainz"."user_type" 
// where "bookbrainz"."user_type"."userTypeId" in ($1)
// - column user_type.userTypeId does not exist