Rails 3.2 + Paperclip: Assign default image on user creation

Question

I am working on adding a profile picture to the User model in my Rails app. I've already gotten screenshots successfully working with another model, but for some reason I'm having a lot of difficulties with profile pictures. To handle profile pictures, I've created a new ProfilePics model:

class ProfilePic < ActiveRecord::Base
  attr_accessible :image, :user_id

  has_attached_file :profile_pic, :default_url => "/system/user_profile_pics/profile.png",
                                  :url => "/system/user_profile_pics/:id/:basename.:extension",
                                  :path => ':rails_root/public:url'
                                  :styles => { :large => "800x400", :thumb => "36x36" }

  # **** Associations ****

  # State that each profile picture can have an associated user
  belongs_to :users

  # **** Validations ****

  # Only allow the user to upload .bmp, .gif, .jpg, .jpeg, and .png files
  validates_attachment_content_type :image, :content_type => /^image\/(bmp|gif|jpg|jpeg|png)/

  # Validate the presence of the user id
  validates :user_id, :presence => true

  # Order all profile pictures by ID, from first to last
  default_scope :order => 'profile_pics.id ASC'
end

When a user signs up, he/she should be set the default profile picture. This picture is the image file specified in the :default_url argument for the has_attached_file method. However, I can't seem to figure out how to assign the user the default profile picture in the controller, after the User has been created. I don't want to add the profile picture to the sign up form, and if I just omit it from the controller, I receive the following error message:

undefined method `before_image_post_process'

I haven't made the profile picture a requirement on user creation. I believe I have all of the correct database tables set up, but for some reason I keep getting this error. Here's my attempt at assigning the user the default profile picture in the controller:

if @user.save
  # Create a profile picture for the user
  @user.profile_pic = ProfilePic.new(:image => nil, :user_id => @user.id)

  ...
end

When debugging, immediately after saving the user, typing "@user.profile_pic" in the console returns the same 'before_image_post_process' error.

Does anyone have any insight on this issue? Thank you very much in advance!

Answer 1

You are getting this error because you defined the attached file attribute as profile_pic but you are doing the Paperclip validation on the image attribute.

When you define a has_attached_file attribute, Paperclip automatically creates a <name>_post_process callback which it uses later in the validation (where is the name of the has_attached_file attribute).

You created profile_pic_post_process but then the validation is looking for image_post_process, hence the error.

Change your validation line in the ProfilePic model:

  # Only allow the user to upload .bmp, .gif, .jpg, .jpeg, and .png files
  validates_attachment_content_type :profile_pic, :content_type => /^image\/(bmp|gif|jpg|jpeg|png)/