title: JsonApi Serializer Not Found
body: <p>I have run <code>gem 'jsonapi-serializer'</code> and <code>bundle install</code>.</p>
  <p>I then try to run a generator <code>rails g serializer User username id</code> but the command always freezes. So I created the serializer manually:</p>
  <pre class="lang-rb prettyprint-override"><code># app/serializers/user_serializer.rb
  class UserSerializer
    include JSONAPI::Serializer
    attributes :username, :id
  end
  </code></pre>
  <p>but when I call it from my <code>UsersController</code> I get an error:</p>
  <pre class="lang-rb prettyprint-override"><code># app/controllers/user_controller.rb
  class UsersController &lt; ApplicationController
    def show
      render json: { user: UserSerializer.new(User.new(username: 'joe'))}
    end
  end
  </code></pre>
  <p>here the error:</p>
  <pre class="lang-html prettyprint-override"><code>NameError in UsersController#show
  uninitialized constant UsersController::UserSerializer
  </code></pre>
  <p>It seems that the UserSerializer is not loading, and I am not sure where I can tinker to make that work.</p>