Sistema de importação de arquivos csv

application.rb

#config/application.rb

require File.expand_path('../boot', __FILE__)

require 'csv'
require 'rails/all'

Bundler.require(:default, Rails.env)

module Import
  class Application < Rails::Application
  end
end

book.rb

#models/book.rb

class Book < ActiveRecord::Base
  def self.to_csv(options ={})
    CSV.generate(options) do |csv|
      csv << column_names
      all.each do |book|
        csv << product.attributes.values_at(*column_names)
      end
    end
  end
  
  def self.import(file)
    CSV.foreach(file.path, headers: true) do |row|
      Book.create! row.to_hash
    end
  end
end

books_controller.rb

class BooksController < ApplicationController
  before_action :set_book, only: [:show, :edit, :update, :destroy]

  # GET /books
  # GET /books.json
  def index
    @books = Book.all
    respond_to do |format|
      format.html
      format.csv { send_data @book.to_csv }

    end
  end

  def import
    Book.import(params[:file])
    redirect_to root_url, notice: "Products importados"
  end

  # GET /books/1
  # GET /books/1.json
  def show
  end

  # GET /books/new
  def new
    @book = Book.new
  end

  # GET /books/1/edit
  def edit
  end

  # POST /books
  # POST /books.json
  def create
    @book = Book.new(book_params)

    respond_to do |format|
      if @book.save
        format.html { redirect_to @book, notice: 'Book was successfully created.' }
        format.json { render action: 'show', status: :created, location: @book }
      else
        format.html { render action: 'new' }
        format.json { render json: @book.errors, status: :unprocessable_entity }
      end
    end
  end

  # PATCH/PUT /books/1
  # PATCH/PUT /books/1.json
  def update
    respond_to do |format|
      if @book.update(book_params)
        format.html { redirect_to @book, notice: 'Book was successfully updated.' }
        format.json { head :no_content }
      else
        format.html { render action: 'edit' }
        format.json { render json: @book.errors, status: :unprocessable_entity }
      end
    end
  end

  # DELETE /books/1
  # DELETE /books/1.json
  def destroy
    @book.destroy
    respond_to do |format|
      format.html { redirect_to books_url }
      format.json { head :no_content }
    end
  end

  private
    # Use callbacks to share common setup or constraints between actions.
    def set_book
      @book = Book.find(params[:id])
    end

    # Never trust parameters from the scary internet, only allow the white list through.
    def books_params
      params.require(:books).permit(:title, :author, :description, :isbn13)
    end
    
end

index.html.erb

#views/books/index.html.erb

<h1>Listing books</h1>

<table>
  <thead>
    <tr>
      <th>Title</th>
      <th>Author</th>
      <th>Description</th>
      <th></th>
      <th></th>
      <th></th>
    </tr>
  </thead>

  <tbody>
    <% @books.each do |book| %>
      <tr>
        <td><%= book.title %></td>
        <td><%= book.author %></td>
        <td><%= book.description %></td>
        <td><%= link_to 'Show', book %></td>
        <td><%= link_to 'Edit', edit_book_path(book) %></td>
        <td><%= link_to 'Destroy', book, method: :delete, data: { confirm: 'Are you sure?' } %></td>
      </tr>
    <% end %>
  </tbody>
</table>

<br>

<h2>Importar Livros</h2>
<%= form_tag import_books_path, multipart: true do %>
	<%= file_field_tag :file %>
	<%= submit_tag "Import" %>
<% end %>

<%= link_to 'New Book', new_book_path %>

routs.rb

#config/routs.rb

Import::Application.routes.draw do

  resources :books do
    collection { post :import }
  end

  resources :products

  resources :distribuidors
  
  root to: 'books#index'

end

teste.csv