Rails standard controller example

users_controller.rb

class UsersController < ActionController::Base
  before_action :set_user, only: [:show, :edit, :update, :destroy]
  
  def index
    @users = User.all
  end

  def show
  end

  def edit
  end

  def create
    @user = User.new(user_params)
    respond_to do |format|
      if @user.save
        format.html { redirect_to @user, notice: 'User was successfully created.' }
        format.json { render json: @user, status: :created, location: @user}
      else
        format.html { render :new }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
  end

  def update
    respond_to do |format|
      if @user.update_attributes(user_params)
        format.html { redirect_to @user, notice: 'User was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render :edit }
        format.json { render json: @user.errors, status: :unprocessable_entity }
      end
    end
  end

  def destroy
    @product.destroy
    respond_to do |format|
      format.html { redirect_to :index }
      format.json { head :no_content }
    end
  end

  private

  def user_params
    params.require(:user).permit(:username, :password, :password_confirmation)
  end

  def set_user
    @user = User.find(params[:id])
  end
end