RubyOnRails Internal API Call - ruby-on-rails

Question

I am completely new to RubyOnRails so please be careful for even simplest mistakes I could have done. I developed a simple app that displayes some data from a .csv file. Here my code:
class UsersController < ApplicationController
def index
#users = getUsers
end
private def getUsers
invoker = ProviderInvoker.new(UserProvider.new("app/data/user_data.csv"))
invoker.getData
end
end
My app displaying the data as I wanted. No problem so far but I want to create and use an internal API for providing data so I am changing my UsersController into this:
require "net/http"
class UsersController < ApplicationController
def index
uri = URI("http://localhost:3000/api/users")
response = Net::HTTP.get(uri)
#users = JSON.parse(response)
end
end
and created another UsersController under app/controllers/api
class Api::UsersController < ApplicationController
def index
invoker = ProviderInvoker.new(UserProvider.new("app/data/user_data.csv"))
data = invoker.getData
render json: data
end
end
And lastly I created a serializer under app/serializers:
class UsersSerializer < ActiveModel::Serializer
attributes :id, :first_name, :last_name, :email, :user_name
end
When I go to my index page I get an error like
No serializer found for resource: #< User:0x07aaebb0 #id="1", #first_name="Susan", #last_name="Gomez", #email="sgomez0#cpanel. net", #user_name="sgomez0">
Obviously there is something wrong with my serializer but I can't manage to find what.

Answer 1

It is a good practice to put serializer under Api module also, so you won't be confused which serializer you use.
As a try you may set serializer manually in controller, like this:
def index
invoker = ProviderInvoker.new(UserProvider.new("app/data/user_data.csv"))
data = invoker.getData
render json: data, each_serializer: UsersSerializer, adapter: :json
end