Rails: Import Export CSV Data without Gem

Hi Folks,
Recently I was assigned a task to make changes to Rails Admin. So I looked into it and started playing with it and exploring its feature.
I was kinda impressed with one feature of exporting the records in CSV format.

I wanted to give it a try and make my own without using a gem.

Now I knew there was a csv library for ruby. So I started with this library and made a feature for exporting and importing csv files without using gem(though I know I am using a CSV, a inbuilt feature of ruby, then probably i just wanted to see how it works).

CSV Library Doc : http://ruby-doc.org/stdlib-2.0.0/libdoc/csv/rdoc/CSV.html

So, I started by making this example app which has a model Movie and its details.

Source : https://github.com/coderaga/RailsTutos/tree/master/Import-Export-CSV-Data

Code Summary :

#!config/application.rb
require ‘csv’

Now the Routes..

#! routes.rb
resources :movies do
 collection { post :import }
end
root ‘movies#index’

Now the Controller’s

#!movies_controller.rb
def index
 @movies = Movie.all
 respond_to do |format|
 format.html
 format.csv { send_data @movies
              .to_csv([‘title’,
              ‘description’,
 ‘release_date’,
 ‘genre’,
 ‘runtime’,
 ‘rating’]
 )
 }
 end
end
def import
 Movie.import(params[:file])
 redirect_to root_url, notice: ‘Movies Uploaded successfully’
end

Now the main part.. Model and the CSV logic.

#!movie.rb
# == Schema Information
#
# Table name: movies
#
# id :integer not null, primary key
# title :string default(“”)
# description :string default(“”)
# rating :integer default(0)
# release_date :date
# genre :string default(“”)
# runtime :string
# created_at :datetime not null
# updated_at :datetime not null
#
class Movie < ActiveRecord::Base
 
 # Generate a CSV File of All Movie Records
 def self.to_csv(fields = column_names, options={})
   CSV.generate(options) do |csv|
   csv << fields
   all.each do |movie|
     csv << movie.attributes.values_at(*fields)
   end
  end
 end
 # Import CSV, Find or Create Movie by its title.
 # Update the record.
 def self.import(file)
   CSV.foreach(file.path, headers: true) do |row|
     movies_hash = row.to_hash
     movie = find_or_create_by!(title: movies_hash[‘title’])
     movie.update_attributes(movies_hash)
  end
 end
end

And finally showing it in views.

<! — app/views/movies/index.html.erb →
<%=link_to ‘Export to CSV’, movies_path(format: ‘csv’)%>
<%= form_tag import_movies_path, multipart: true do%>
 <%= file_field_tag :file %>
 <%= submit_tag ‘Import CSV’%>
<% end %>

Thank you !