The correct way to define custom bookshelf Collections with registry plugin

bookshelf-registry-collection.js

const bookshelf = require('bookshelf')

class Users extends bookshelf.Collection {
  get model () {
    return User
  }
}

class User extends bookshelf.Model {
  static collection (...args) {
    return new Users(...args)
  }
}

bookshelf.collection('Users', Users)
bookshelf.model('User', User)

const account = await bookshelf.model('Account').forge({ id: 1 }).fetch({ withRelated: 'users' })
account.related('users') instanceof Users // -> true
account.users() instanceof Users // -> true
bookshelf.model('User').collection() instanceof Users // -> true

This'll also allow to define custom logic when collection is eager loaded:

class Users extends bookshelf.Collection {
  initialize (...args) {
    super.initialize(...args)
    this.on('fetching', (collection, attrs, options) => {
      if (options.isEager) {
        // Collection is eager loaded, do something amazing
      }
    }
  }
}