title: How do I solve this issue of ActiveModel::Serializer::Null::with Hash
body: <p>I am trying to register a student using the API. I am using postman to test. Here are my logs whenever I try to post a new student</p>
  
  <pre><code>Started POST "/api/v1/students/" for 127.0.0.1 at 2017-12-29 12:11:12 -0500
  Processing by Api::V1::StudentsController#create as */*
  [active_model_serializers] Rendered ActiveModel::Serializer::Null with Hash 
  (0.12ms)
  Filter chain halted as :authenticate_user! rendered or redirected
  Completed 401 Unauthorized in 3ms (Views: 1.1ms | ActiveRecord: 0.0ms)
  
  Started POST "/api/v1/students/" for 127.0.0.1 at 2017-12-29 12:14:07 -0500
  Processing by Api::V1::StudentsController#create as */*
  [active_model_serializers] Rendered ActiveModel::Serializer::Null with Hash 
  (0.19ms)
  Filter chain halted as :authenticate_user! rendered or redirected
  Completed 401 Unauthorized in 106ms (Views: 103.7ms | ActiveRecord: 0.0ms)
  </code></pre>
  
  <p>And here is my controller:</p>
  
  <pre><code>class Api::V1::StudentsController &lt; Api::V1::BaseController
  
      def create
          student = Student.new(student_params)
  
          if student.save
              render json: {status: 'SUCCESS', message: 'Registered', data: student_data}, status: :ok
          else
              render json: {status: 'ERROR', message: 'Student not registered', data: student.errors}, status: :unprocessable_entity
          end 
      end
  
  end
  </code></pre>