json_presenter.rb

class ReportJSONPresenter
  attr_reader :report

  def initialize(report)
    @report = report
  end

  def to_h
    {
      name: report.name,
      template: report.query_template
    }
  end

  def to_json
    to_h.to_json
  end
end

class ReportsJSONPresenter
  attr_reader :collection

  def intializer(collection)
    @collection = collection
  end

  def to_a
    array = []
    collection.each do |item|
      array << ReportJSONPresenter.new(item)
    end
    array
  end

  def to_json
    array.to_json
  end
end

class ReportsController < ApplicationController
  def index
    reports = Report.all
    render json: ReportsJSONPresenter.new(reports)
  end

  def show
    report = Report.find(params[:id])
    render json: ReportSerializer.new(report).to_json
  end
end