RAILS: UPLOADING PHOTOS VIA AMAZON S3 AND PAPERCLIP (UPLOADING FILES TO S3 IN RUBY WITH PAPERCLIP)

Set up Ruby on Rails with Paperclip and S3 using AWS SDK
Uploading Files to S3 in Ruby with Paperclip

Paperclip requires the following gems added to your Gemfile.

If your paperclip version is 5.1.0 then we are using 'aws-sdk' version 2.3.

# Gemfile
gem 'paperclip'
gem 'aws-sdk', '~> 2.3'

or our paperclip version is 4.1.0 then we need to use 'aws-sdk' version < 2  (note: add version less than 2.0 otherwise you will get paperclip error)

gem 'paperclip'
gem 'aws-sdk', '< 2.0'

Run bundle install and restart the Rails server after modifying the Gemfile.

Then run the command :-

rails generate paperclip user image

Define the file attribute in the Model

class User < ActiveRecord::Base
    has_attached_file :image, styles: { medium: "300x300>", thumb: "100x100>" }, default_url: "/images/:style/missing.png"
      validates_attachment_content_type :image, content_type: /\Aimage\/.*\z/
end

Migrations: Now our migration file look like :-

class AddAvatarColumnsToUsers < ActiveRecord::Migration
  def up
    add_attachment :users, :image
  end

  def down
    remove_attachment :users, :image
  end
end

View Page :-

<%= form_for @user, url: users_path, html: { multipart: true } do |form| %>
  <%= form.file_field :image %>
<% end %>

Now in the controller :-

def create
  @user = User.create( user_params )
end

private
def user_params
  params.require(:user).permit(:image)
end

In our view page we can show the image using :-

<%= image_tag @user.image.url %>
<%= image_tag @user.image.url(:medium) %>
<%= image_tag @user.image.url(:thumb) %>

After that :- 
S3 bucket Implementation:-

1. Go to Aws Console
2. Create the s3 bucket with bucket name and choose specific region.
3. Get the app_key and app_secret (link: https://www.multcloud.com/tutorials/s3-key.html)

We’ll also need to specify the AWS configuration variables for the development/production Environment.

# config/environments/production.rb

config.paperclip_defaults = {
    storage: :s3,
    s3_credentials: {
    bucket: ENV.fetch('S3_BUCKET_NAME'),
    access_key_id: ENV.fetch('AWS_ACCESS_KEY_ID'),
    secret_access_key: ENV.fetch('AWS_SECRET_ACCESS_KEY'),
    s3_region: ENV.fetch('AWS_REGION')   
    }
  }

If we are getting problem with http or https s3 image path then you can do that :-

config.paperclip_defaults = { storage: :s3, s3_protocol: :http, s3_host_name: "s3.us-east-2.amazonaws.com", bucket: ENV.fetch('S3_BUCKET_NAME'), s3_credentials: { access_key_id: ENV.fetch('AWS_ACCESS_KEY_ID'), secret_access_key: ENV.fetch('AWS_SECRET_ACCESS_KEY'), s3_region: ENV.fetch('AWS_REGION')     }, s3_permission: { :original => :public }} 

OR IF YOU ARE CREATING NEW FILE IN CONFIG FOLDER FOR SAVING THE S3 CREDENTIALS THEN WE JUST HAVE TO CHANGE OUR MODEL SETTING AND WE CAN GET THE S3_CREDENTIALS FROM CONFIG FILE :-

Model :-

class User < ActiveRecord::Base
     has_attached_file :image,:styles => { :icon => "50x50>", :small => "150x150", :medium => "300x300>", :thumb => "100x100>" }, :default_url => "/assets/icons/picture.png", :storage => :s3,:s3_credentials => "#{Rails.root}/config/aws_s3.yml",:url => ':s3_domain_url', :path=> ":attachment/:id/:style/:filename"

      validates_attachment_content_type :image, :content_type => /\Aimage\/.*\Z/
end

# config/aws_s3.yml

development:
bucket: ENV.fetch('S3_BUCKET_NAME')
access_key_id: ENV.fetch('AWS_ACCESS_KEY_ID')
secret_access_key: ENV.fetch('AWS_SECRET_ACCESS_KEY')
s3_region: ENV.fetch('AWS_REGION')


WE CAN REFER :-

https://github.com/thoughtbot/paperclip
https://devcenter.heroku.com/articles/paperclip-s3#define-the-file-attribute-in-the-model
https://coderwall.com/p/vv1iwg/set-up-ruby-on-rails-with-paperclip-5-and-s3-using-aws-sdk-v2
http://www.korenlc.com/rails-uploading-photos-via-amazon-s3-and-paperclip/