Rails + CarrierWave: NoMethodError: undefined method `name' for nil:NilClass - ruby-on-rails

Question

I am using CarrierWave with Rails 3.1. I am getting the following error message when I submit the form (trying to upload an image):
Error Message:
ActiveRecord::StatementInvalid in Admin::PostsController#create
NoMethodError: undefined method `name' for nil:NilClass: INSERT INTO "posts" ("body", "created_at", "draft", "image", "post_type", "title", "updated_at", "user_id") VALUES (?, ?, ?, ?, ?, ?, ?, ?)
Rails.root: /Users/aziz/Sandbox/ruby/rails/Tumblelog
Application Trace | Framework Trace | Full Trace
app/controllers/admin/posts_controller.rb:18:in `create'
Request
Parameters:
{"utf8"=>"✓",
"authenticity_token"=>"za+zNRDGNCcujnCmO726cWCo2ze1rgaXv5bL17JGaek=",
"post"=>{"image"=>#<ActionDispatch::Http::UploadedFile:0x000001014aeff0 #original_filename="AzizLight.jpeg",
#content_type="image/jpeg",
#headers="Content-Disposition: form-data; name=\"post[image]\"; filename=\"AzizLight.jpeg\"\r\nContent-Type: image/jpeg\r\n",
#tempfile=#<File:/var/folders/ky/2ddtbt0d7k1g__2ctr8njcfc0000gn/T/RackMultipart20110918-21704-hp2ajt>>,
"draft"=>"0",
"user_id"=>"2",
"post_type"=>"image"},
"commit"=>"Post"}
The problem is that I don't know where this name comes from and I don't know what variable is being nil, so I can't debug properly (I tried to debug a log before asking here).
Line 18 corresponds to the #post.save line in the following controller:
PostsController:
# ...
def new
#post = Post.new
#form_html_options = (params[:post_type] == "image") ? { :multipart => true } : {}
#form_partial = get_form_partial(params[:post_type])
redirect_to admin_posts_path, :alert => "You tried to create an unknown type of post..." if #form_partial.nil?
#title = "Creating a new post..."
end
def create
#post = Post.new(params[:post])
if #post.save
flash[:success] = "Post created successfully!"
redirect_to admin_post_path(#post)
else
#title = "Creating a new post..."
#form_partial = get_form_partial(params[:post][:post_type])
render 'new'
end
end
# ...
Here other files that might be needed to spot the problem:
Post (model):
attr_accessible :title, :body, :user_id, :draft, :post_type, :image
belongs_to :user
mount_uploader :image_url, ImageUploader
ImageUploader:
class ImageUploader < CarrierWave::Uploader::Base
include CarrierWave::RMagick
storage :fog
def extension_white_list
%w(jpg jpeg gif png)
end
end
new.html.erb:
<h1><%= #title %></h1>
<%= form_for #post, :url => admin_posts_path, :html => #form_html_options do |f| %>
<%= render 'form', :f => f %>
<% end %>
_form.html.erb:
<%= render 'error_messages' %>
<%= render #form_partial, :f => f %>
<p class="drop-down">
<%= f.label :draft, 'Status' %>
<%= f.select(:draft, options_for_select([["Published", 0], ["Draft", 1]], (#post.new_record? ? 0: #post.draft))) %>
</p>
<%= f.hidden_field :user_id, :value => #post.user_id || current_user.id %>
<%= f.hidden_field :post_type, :value => #post.post_type || params[:post_type] %>
<p class="button"><%= f.submit "Post", :disable_with => 'Posting...' %></p>
_image_form.html.erb (#form_partial):
<p><%= f.file_field :image %></p>
So what it really going on please?

Answer 1

Your image uploader class was not loaded into your current rails server thread. Reload rails server and it should work fine =).

Answer 2

Make sure you use - mount_uploader :image, ImageUploader in your model like here -
class CarImage < ActiveRecord::Base
belongs_to :car
mount_uploader :image, ImageUploader
end
Regards
Robbie

Answer 3

I experienced the some problem and the cause is (probably always) that the UploadedFile object has been sent to the attribute carrierwave was mounted on. The db adapter cannot serialize this object and will therefore throw this error.
Make sure that:
the uploader has been properly mounted
you don't use write_attribute to write the uploaded file (which was the cause of my problem). Use the accessor instead: model.send('image=', params[:model][:image]). Uglier, but better.

Answer 4

Make sure in your model:
mount_uploader :image, ImageLoader
Remember that :image must be the string/text type.

Answer 5

I came across this post because I had the same error you described, but restarting the server didn't resolve it (as suggested by other answers). In my case, the problem was caused because I used mount_uploader before attr_accessible. By switching them I solved the problem.

Answer 6

I had a similar problem.
Solution was changing:
attr_accessible :title, :body, :user_id, :draft, :post_type, :image
belongs_to :user
mount_uploader :image_url, ImageUploader
to:
attr_accessible :title, :body, :user_id, :draft, :post_type, :image_url
belongs_to :user
mount_uploader :image_url, ImageUploader