Question

I have one original object post.rb with the next fields or attributes.

class Post
 include Mongoid::Document
 mount_uploader :posted, PostedUploader, mount_on: :posted_filename
 field :posted
 field :remote_posted_url

 attr_accessible :posted, :remote_posted_url
end

Then I want create a copy from the first original object and share images for the new object. Then I doing:

attribs = @post.attributes.select {|a| %w(posted remote_posted_url).include? a }
new_post = Post.new attribs
new_post.save

So far, everything works fine the new object, share the images of the original. The two objects have the same shared image with the same path.

The problem is if I delete the original object, the clone object can not find the image because I deleted in original post.

How can I, in my destroy action object, with a callback before_destroy, check whether the image is used by one or more objects.

if the image, using 2 or more objects,

Not delete the image.

otherwise, if the image is used by a single object,

Delete the image.

Its possible?

I’m need a method to verify this problem.

Answer 1

Override the remove_posted callback injected by CW in your model:

class Post
  include Mongoid::Document
  mount_uploader :posted, PostedUploader, mount_on: :posted_filename
  field :posted
  field :remote_posted_url

  attr_accessible :posted, :remote_posted_url

  # override as to not delete if there's another model storing the same image
  def remove_posted!
    super unless Post.where(posted_filename: posted_filename).count > 1
  end
end

PS: Post.new(attribs).save should be copying the file, not use the same one, maybe you ought to assign a File.open(path) to the posted column insted of the uploader.