Rails Controller CURD

base_controller.rb

class BaseController < ApplicationController
  before_action :set_resource, only: %i[ show edit ]

  def index
    resources = resource_class.all
    instance_variable_set("@#{resources_name}", resources)
  end

  def create
    @resource = resource_class.new(resource_params)

    respond_to do |format|
      if @resource.save
        format.html { redirect_to @resource, notice: "#{resource_name} was successfully created." }
        format.json { render :show, status: :created, location: @resource }
      else
        format.html { render :new, status: :unprocessable_entity }
        format.json { render json: @resource.errors, status: :unprocessable_entity }
      end
    end
  end

  def new
    resource = resource_class.new
    instance_variable_set("@#{resource_name}", resource)
  end

  def show
  end

  def edit
  end

  def update
    @resource = resource_class.find(params[:id])

    respond_to do |format|
      if @resource.update(resource_params)
        format.html { redirect_to @resource, notice: "#{resource_name} was successfully updated." }
        format.json { render :show, status: :ok, location: @resource }
      else
        format.html { render :edit, status: :unprocessable_entity }
        format.json { render json: @resource.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
    @resource = resource_class.find(params[:id])

    @resource.destroy
    respond_to do |format|
      format.html { redirect_to "#{controller_name}_url", notice: "#{resource_name} was successfully destroyed." }
      format.json { head :no_content }
    end
  end

  def set_resource
    resource ||= resource_class.find(params[:id])
    instance_variable_set("@#{resource_name}", resource)
  end

  def resource_class
    @resource_class ||= resource_name.classify.constantize
  end

  def resource_name
    @resource_name ||= controller_name.singularize
  end

  def resources_name
    @resources_name ||= controller_name
  end
end

courses_controller.rb

class CoursesController < BaseController

  private
  def resource_params
    params.require(:course).permit(:title, :credit_hours, :code, :year)
  end
end

sections_controller.rb

class SectionsController < BaseController

  private
  def resource_params
      params.require(:section).permit(:name)
    end
end

students_controller.rb

class StudentsController < BaseController

  private
  def resource_params
    params.require(:student).permit(:first_name, :last_name, :roll_no, :date_of_birth)
  end
end