Paperclip app using Ruby on Rails



kiran@kiran:~/Desktop/today$ cd paperclip                                                                    
kiran@kiran:~/Desktop/today/paperclip$

kiran@kiran:~/Desktop/today/paperclip$ rails g scaffold Paper name:string email:string

kiran@kiran:~/Desktop/today/paperclip$ rake db:migrate                                                    

kiran@kiran:~/Desktop/today/paperclip$ rails s                                                                    

Now Open you Gemfile and add...                                                                                       
  
gem 'paperclip', '~> 4.3.0'

bundle install                                                                                                                        

Note: After that you have to migrate the rails model with your image.                                

 kiran@kiran:~/Desktop/today/paperclip$ rails g migration add_image_to_papers

Now open your db/migration/20150618055156_add_image_to_papers.rb                    

and add the follwing

class AddImageToPapers < ActiveRecord::Migration
def self.up
add_column :papers, :image_file_name, :string
add_column :papers, :image_content_type, :string
add_column :papers, :image_file_size, :integer
add_column :papers, :image_updated_at, :datetime
end
def self.down
remove_column :papers, :image_file_name
remove_column :papers, :image_content_type
remove_column :papers, :image_file_size
add_column :papers, :image_updated_at
end

end

After you will go your model app/models/paper.rb                                                              


class Paper < ActiveRecord::Base
has_attached_file :image
end

Then after you will go and open to change modifications app/views/papers/_form.html.erb


adding your form name in the 1st line of your form. This is used for mutliple images you can upload.


<%= form_for(@paper, :html => {:multipart => true}) do |f| %>


and then add field in same app/views/papers/_form.html.erb

<div class="field">
<%= f.label :image %><br>
<%= f.file_field :image %>
</div>

If you got any error like this                                                                                                    

 "undefined method for `has_attached_file`” 


then restart your rails server.

Option 1: Validate content type                                         


Now open your model:  app/models/paper.rb

validates_attachment_content_type
   :image, :content_type => ["image/jpg", "image/jpeg",
   "image/png", "image/gif"]
-OR- another way
validates_attachment
   :image, content_type: { content_type: ["image/jpg",
   "image/jpeg", "image/png", "image/gif"]
   }

Note: This is tagged as Rails 4, so I think the strong parameter whitelisting in your controller should do fine. Take out the
attr_accessor :image_file_nameand it should work.


If you are using Rails 4 below then use attr_accessors in your model


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