image_uploader.rb

# encoding: utf-8

class ImageUploader < CarrierWave::Uploader::Base

  # Include RMagick or MiniMagick support:
   #include CarrierWave::RMagick
  include CarrierWave::MiniMagick

  # Choose what kind of storage to use for this uploader:
  storage :file
  # storage :fog

  # Override the directory where uploaded files will be stored.
  # This is a sensible default for uploaders that are meant to be mounted:
  def store_dir
    "uploads/#{model.random_id}"
  end

  # Provide a default URL as a default if there hasn't been a file uploaded:
  # def default_url
  #   # For Rails 3.1+ asset pipeline compatibility:
  #   # ActionController::Base.helpers.asset_path("fallback/" + [version_name, "default.png"].compact.join('_'))
  #
  #   "/images/fallback/" + [version_name, "default.png"].compact.join('_')
  # end

  # Process files as they are uploaded:
  # process :scale => [200, 300]
  #
  # def scale(width, height)
  #   # do something
  # end

  def remove_animation
   manipulate! do |img, index|
      index == 0 ? img : nil
    end
  end

  # Create different versions of your uploaded files:
  version :thumb do
    process :remove_animation
    process :resize_to_fill => [100, 100]
    process :convert => 'jpg'
  end

  version :resized do
    process :resize_to_limit => [500,1000]
  end

  #

  # Add a white list of extensions which are allowed to be uploaded.
  # For images you might use something like this:
  def extension_white_list
     %w(jpg jpeg gif png)
  end

  # Override the filename of the uploaded files:
  # Avoid using model.id or version_name here, see uploader/store.rb for details.
  # def filename
  #   "something.jpg" if original_filename
  # end

end

images_controller.rb

class ImagesController < ApplicationController
  before_action :authenticate_user!, :except => [:show]
  def new
    @image = Image.new
  end

  def create
    @image = Image.create(image_params)
    if @image.save
      redirect_to image_path(@image.random_id)
    else
      render 'new'
    end
  end

  def show
    @image = Image.friendly.find(params[:id])
  end

  def destroy
    @image = Image.friendly.find(params[:id])
    @image.destroy
    respond_to do |format|
      format.js { render 'new'}
      format.html { redirect_to root_path }
    end
  end

  private
    def image_params
      params.require(:image).permit(:user_id, :title, :image, :random_id)
    end
end