rails-module-carrierwave

Rails module for carrierwave.

step by step:

• install gem:

gem 'carrierwave', '~> 0.10.0'
gem 'mini_magick', '~> 4.3'

• generate basic code:

rails g scaffold Pet name:string description:text image:string
rake db:migrate

• create carrievave config file:

# *config/initializers/carrier_wave.rb*
require 'carrierwave/orm/activerecord'

rails generate uploader Image
# you can modify the config

• First, uncomment the MiniMagick line. That should be line 7.

include CarrierWave::MiniMagick

• model with validates:

class Pet < ApplicationRecord
    mount_uploader :image, ImageUploader


    validates_processing_of :image
    validate :image_size_validation
    
    private
    def image_size_validation
        errors[:image] << "should be less than 500KB" if image.size > 0.5.megabytes
    end
end

• modify html.erb part:
  • show part:

  ## old:
  <%= @pet.image %>
  ## new:
  <%= image_tag @pet.image.thumb.url %>

  • upload part:

  <!--Old-->
  <div class="field">
      <%= f.label :image %>
      <%= f.file_text :image %>
  </div>
  
  <!--New-->
  <div class="field">
      <%= f.label :image %>
      <%= f.file_field :image %>
  
  
      <% if f.object.image? %>
          <%= image_tag f.object.image.thumb.url %>
          <%= f.label :remove_image %>
          <%= f.check_box :remove_image %> 
      <% end %>
  </div>

resources:

• https://code.tutsplus.com/tutorials/rails-image-upload-using-carrierwave-in-a-rails-app--cms-25183
• https://github.com/carrierwaveuploader/carrierwave
• http://railscasts.com/episodes/253-carrierwave-file-uploads
• http://www.jianshu.com/p/3105b3a3b7c6