Question

I’m very new to Rails, so it’s likely there’s a simple concept here that I’m just not getting, but here’s what’s happening.

I have a User model (powered by Devise), and each user has it’s own respective photo attribute. I know I could have included the photo as part of the User, but the photos are actually the core content of the site, so I preferred them to be their own table. The photo model has a paperclip attachment which handles the actual photo file.

Here’s the issue: Everything works according to plan when I upload a photo as a user, but for some reason, when I return to the photo upload page, the photo I just uploaded gets deleted. I’ve tracked it down to this line of code:

@photo = @user.build_photo

If I don’t call that, the form for the upload throws a nil class error because @user.photo doesn’t exist, but when I DO call it, it deletes the previously uploaded photo, which is weird, because as far as I know, it’s the create function that alters the database, not the build.

Here’s what the server shows:

Started GET “/settings” for 127.0.0.1 at 2012-03-08 10:19:21 -0800
Processing by SettingsController#index as HTML User Load (0.3ms)
SELECT users.* FROM users WHERE users.id = 6 LIMIT 1 Photo
Load (0.3ms) SELECT photos.* FROM photos WHERE photos.user_id
= 6 LIMIT 1 (0.2ms) BEGIN [paperclip] Scheduling attachments for deletion. SQL (0.6ms) DELETE FROM photos WHERE photos.id = 20
[paperclip] Deleting attachments.

And here’s a couple of my models and controllers:

class SettingsController < ApplicationController
    def index
        @user = current_user
        @photo = @user.build_photo
    end
end

<h1>Settings Page</h2>
<%= image_tag @user.photo.the_photo.url(:medium) %>
<%= form_for [@user, @photo], :html => { :multipart => true } do |f| %>
    <%= f.file_field :the_photo %>
    <%= f.submit %>
<% end %>


class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :token_authenticatable, :encryptable, :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable,
         :recoverable, :rememberable, :trackable, :validatable

  # Setup accessible (or protected) attributes for your model
  attr_accessible :email, :password, :password_confirmation, :remember_me, :name, :photo_attribute

  has_one :photo, :dependent => :destroy
  accepts_nested_attributes_for :photo
end

class PhotosController < ApplicationController
    def create
        @user = current_user
        @photo = @user.create_photo(params[:photo])
        redirect_to root_path
    end

    def update
        @user = current_user
        @photo = @user.photo
        if @photo.update_attributes(params[:photo])
            redirect_to settings_path
        else
            redirect_to settings_path
        end
    end

    def destroy
    end
end

Answer 1

As you’ve discovered, calling @user.build_photo will remove a photo for that user if one already exists. You just need to skip doing the build in that case:

@photo = @user.photo || @user.build_photo