Carrierwave image upload in nested form still creating record even no file is specified

I have a Carrierwave image upload in a nested simple_form which works (sort of) unless the user does not specify a file, in which case a blank Picture object is created unless there was a previously existing one. Not quite sure how to make it so that if the user doesn't specify a "new" image to upload, the old one isn't deleted and/or a blank record without a file is created.

One (maybe odd) thing I am doing is always sending the logged in @user to the user#edit action, then building a @user.picture if it doesn't exist. I am thinking this is where my bad design is.

    # user.rb
    class User < ActiveRecord::Base
    [...]

      has_one :picture, :dependent => :destroy
      accepts_nested_attributes_for :picture

    [...]
    end

    # picture.rb
    class Picture < ActiveRecord::Base
      attr_accessible :image, :remove_image
      belongs_to :user
      mount_uploader :image, ImageUploader
    end

    # users_controller.rb
    def edit
      if @user.picture.nil?
        @user.build_picture
      end
    end

    #_form.html.erb
    <%= simp开发者_C百科le_form_for @user, :html => {:multipart => true} do |f| %>
      <%= render "shared/error_messages", :target => @user %>  
      <h2>Picture</h2>
      <%= f.simple_fields_for :picture do |pic| %>
        <% if @user.picture.image? %>
          <%= image_tag @user.picture.image_url(:thumb).to_s %>     
          <%= pic.input :remove_image, :label => "Remove", :as => :boolean %>
        <% end %>
        <%= pic.input :image, :as => :file, :label => "Picture" %>
        <%= pic.input :image_cache, :as => :hidden %>
      <% end %>
      <br/>
    #rest of form here
    <% end %>

I think I had the same issue which I solved by adding a reject_if option to the accepts_nested_attribute. So in your example, you could do something like

class User < ActiveRecord::Base
[...]

  has_one :picture, :dependent => :destroy
  accepts_nested_attributes_for :picture,
    :reject_if => lambda { |p| p.image.blank? }

[...]
end

When you use build_* it sets the foreign key on the object. ( similar to saying Picture.new(:user_id => id) )

Try This

# users_controller.rb
def edit
  if @user.picture.nil?
    @user.picture = Picture.new
  end
end

Today I had the same problem, I solved this like:

  accepts_nested_attributes_for :photos,
    :reject_if => :all_blank