reminder.rb

class Reminder < ApplicationRecord
  attr_accessor :reminder_text, :reminder_date
end

reminder_controller.rb

# frozen_string_literal: true

# API controller for Reminder
class ReminderController < ApplicationController
  # GET /reminders
  def index
    @reminders = Reminder.all
    json_response(@reminders)
  end

  # POST /reminder
  def create
    @reminder = Reminder.create!(reminder_params)
    json_response(@reminder, :created)
  end

  # GET /reminder/:id
  def show
    json_response(@reminder)
  end

  # DELETE /reminder/:id
  def destroy
    @reminder.destroy
    head :no_content
  end

  private

  def reminder_params
    # whitelist params
    pars = params.permit(:reminder_text, :reminder_date)
    puts pars
    pars
  end

  def set_reminder
    @reminder = Reminder.find(params[:id])
  end
end

response.rb

# frozen_string_literal: true

# Return a 200 response with the given object
module Response
  def json_response(object, status = :ok)
    puts object
    render json: object, status: status
  end
end

response.txt

Started POST "/reminder" for 127.0.0.1 at 2019-01-25 13:58:31 +0000
   (0.1ms)  SELECT "schema_migrations"."version" FROM "schema_migrations" ORDER BY "schema_migrations"."version" ASC
  ↳ /Library/Ruby/Gems/2.3.0/gems/activerecord-5.2.2/lib/active_record/log_subscriber.rb:98
Processing by ReminderController#create as */*
  Parameters: {"reminder_text"=>"hi", "reminder_date"=>1548350451, "reminder"=>{"reminder_text"=>"hi", "reminder_date"=>1548350451}}
Unpermitted parameter: :reminder
putting pars
{"reminder_text"=>"hi", "reminder_date"=>1548350451}
   (0.0ms)  begin transaction
  ↳ app/controllers/reminder_controller.rb:13
  Reminder Create (0.4ms)  INSERT INTO "reminders" ("created_at", "updated_at") VALUES (?, ?)  [["created_at", "2019-01-25 13:58:31.343583"], ["updated_at", "2019-01-25 13:58:31.343583"]]
  ↳ app/controllers/reminder_controller.rb:13
   (0.8ms)  commit transaction
  ↳ app/controllers/reminder_controller.rb:13
#<Reminder:0x007fc7209e1850>
Completed 201 Created in 30ms (Views: 0.7ms | ActiveRecord: 2.6ms)